[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Yep. Haven't run the calculations, but yes, an extra resistor has to be added in the dp cathode leg. On Jan 31, 8:29 pm, will ossumguyw...@gmail.com wrote: Quick question-I noticed the current rating of the decimal points on my IN-14 tubes was .3mA. Do I need to put a ~100K resistor on the cathodes of the decimal points to keep them from being run at the same current as the rest of the tube? -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Quick question-I noticed the current rating of the decimal points on my IN-14 tubes was .3mA. Do I need to put a ~100K resistor on the cathodes of the decimal points to keep them from being run at the same current as the rest of the tube? -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Hi all, been following this discussion with interest I have learnt quite a bit from it myself, thanks, getting the 'courage' to build my own nixie circuit rather than copying others. However I just had to jump in (both feet first) Will you really want to listen to somebody else other than your 'electrician' (HE needs to go back to college, I AM an electrician/ electrical engineer) YOU will not be laughing when someone DIES to to faulty wiring! It is possible. Your equipment is telling you there is a fault, the guys here are telling you it is a 'hazard'. By hazard we mean 'Hazardous to health'! Every year hundreds of people DIE due to faulty wiring, from both electrical shock and fires! This is why untrained people should STAY AWAY from 'mains' HV wiring. (And is illegal in so many countries.) Sorry to be so forceful but you are putting not just yourself at risk (Evolution may sort that out) but others as well. Go back to basics (Maybe you have not learnt the basics yet, being a 'software' person?) and learn the dangers of electricity THEN start to tamper with it, you (and me) are getting some great advise here, but your coming over with a 'I know it all attitude' that will get someone hurt, listen and learn my friend. And thanks to all for the great advise and ideas) Dave. On 26 Jan, 04:26, will ossumguyw...@gmail.com wrote: Lol... Doesn't seem to be a hazard thus far... I trust the electrician. On Jan 25, 8:59 pm, JohnK yend...@internode.on.net wrote: Evolution-in-Action John K. - Original Message - From: will ossumguyw...@gmail.com ...clip... The surge protector always says wiring fault, but everything seems to work OK. ...clip -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
And I need to learn to spell 'advise'? Maybe 'advice' would be better, lol. On 26 Jan, 14:44, Lucky dave.lucky.po...@gmail.com wrote: Hi all, been following this discussion with interest I have learnt quite a bit from it myself, thanks, getting the 'courage' to build my own nixie circuit rather than copying others. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Obligatory.. http://media.photobucket.com/image/lol%20electrician/sss240/Darwin_award_2008.jpg GastonP wrote: You know what they say... Trust kills the man and get the woman pregnant... The wiring fault indication and what you describe on the neon devices ionizing lightly fits with a fault in isolation together with a safety ground failure or mis-wiring. Be careful there... it *is* a hazard. On Jan 26, 1:26 am, will ossumguyw...@gmail.com wrote: Lol... Doesn't seem to be a hazard thus far... I trust the electrician. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Silly buggers, you can see what they are doing wrong there...they are not wearing any sunscreen!! Pfff On 26 Jan, 16:32, Adam Jacobs a...@jacobs.us wrote: Obligatory..http://media.photobucket.com/image/lol%20electrician/sss240/Darwin_aw... GastonP wrote: You know what they say... Trust kills the man and get the woman pregnant... The wiring fault indication and what you describe on the neon devices ionizing lightly fits with a fault in isolation together with a safety ground failure or mis-wiring. Be careful there... it *is* a hazard. On Jan 26, 1:26 am, will ossumguyw...@gmail.com wrote: Lol... Doesn't seem to be a hazard thus far... I trust the electrician. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
On Jan 22, 9:19 pm, will ossumguyw...@gmail.com wrote: 1.When the device is plugged in, even with the surge protector turned off, if I touch any of the neon lamps they light up a little bit (and if I touch them on the common cathode side, the other lamp lights up too). I feel no electrical sensation. This isn't really a concern, just cool. This may be an item of concern. First, do you have bleeder resistors across any high voltage capactors in your circuit? If not, you should, for protection of anyone who may work on it. The neons could be lighting up from stored charge. Also, (assuming that the plugs of both the surge protector and the clock are either 3-prong or polarized) there may be a problem with either your power outlet or surge protector. Either the power outlet wiring's polarity is reversed, or the surge protector has its switch in the wrong wire. If your clock already has bleeder resistors, this is almost certainly the case. If you have any non-polarized plugs in the loop, one of them needs to be reversed, or better yet, replaced with a polarized plug installed properly. The miswiring results in the neutral wire being switched off instead of the live wire, which is a dangerous situation, and can result in just enough current flow to produce the phenomenon you described. I once had a gas range with electronic ignition that was on a mis-wired circuit, and even when it was off the electronic ignition would spark every 10 minutes or so, because the wiring capacitance allowed a trickle of current to flow backwards into the HV generation circuit, and it took that long for it to build up enough to flash over. When off, your clock may be generating a high voltage that is fairly low, perhaps in the region of 70 volts, that is just enough to light the neon bulbs with the additional capacitance from your hand. A.J. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Yes, the caps can bleed through A)the feedback resistor and B)a resistor I keep across V+ and ground to keep the voltage stable when I turn all the lamps off. However, if you think improper wiring can cause this, there's a high chance that's it. I live in an old house with crappy wiring. The surge protector always says wiring fault, but everything seems to work OK. On Jan 25, 8:00 pm, A.J. Franzman a.j.franz...@verizon.net wrote: On Jan 22, 9:19 pm, will ossumguyw...@gmail.com wrote: 1.When the device is plugged in, even with the surge protector turned off, if I touch any of the neon lamps they light up a little bit (and if I touch them on the common cathode side, the other lamp lights up too). I feel no electrical sensation. This isn't really a concern, just cool. This may be an item of concern. First, do you have bleeder resistors across any high voltage capactors in your circuit? If not, you should, for protection of anyone who may work on it. The neons could be lighting up from stored charge. Also, (assuming that the plugs of both the surge protector and the clock are either 3-prong or polarized) there may be a problem with either your power outlet or surge protector. Either the power outlet wiring's polarity is reversed, or the surge protector has its switch in the wrong wire. If your clock already has bleeder resistors, this is almost certainly the case. If you have any non-polarized plugs in the loop, one of them needs to be reversed, or better yet, replaced with a polarized plug installed properly. The miswiring results in the neutral wire being switched off instead of the live wire, which is a dangerous situation, and can result in just enough current flow to produce the phenomenon you described. I once had a gas range with electronic ignition that was on a mis-wired circuit, and even when it was off the electronic ignition would spark every 10 minutes or so, because the wiring capacitance allowed a trickle of current to flow backwards into the HV generation circuit, and it took that long for it to build up enough to flash over. When off, your clock may be generating a high voltage that is fairly low, perhaps in the region of 70 volts, that is just enough to light the neon bulbs with the additional capacitance from your hand. A.J. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Lol... Doesn't seem to be a hazard thus far... I trust the electrician. On Jan 25, 8:59 pm, JohnK yend...@internode.on.net wrote: Evolution-in-Action John K. - Original Message - From: will ossumguyw...@gmail.com ...clip... The surge protector always says wiring fault, but everything seems to work OK. ...clip -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
No, No, No. That's only if there was no MPSA92 in the circuit. Remember, the Base- emitter junction of a transistor is a simple PN junction, ie a diode, and will act like one. The forward voltage will be limited to about 0.6V to 0.7V for your common silicon transistor. (Wiki a silicon diode) If the forward voltage is below 0.7V (for silicon), the base- emitter impedance is high, hence the need for that bleeder resistor, but when the voltage exceeds, or tries to exceed, that 0.7V 'knee', the impedance drops sharply (to close to zero ohms, ideally). Ohms law only works for linear components like resistors (AC or DC), and capacitors and inductors (AC only). PN junctions on semiconductors (diodes, including LEDs. and bipolar transistors) and gas filled tubes (nixies) are VERY non-linear. Think of them all as regulator diodes, that like one specific voltage to operate at. Of course, that voltage is different for each device. If that logic for 2 10Ks in series works. ie 190V supply and 85V across each 10K resistor, then with the 1M, there should be 188V across it and 2V across the other 10K. And it would, if you only had the 2 resistors, but you don't. In Jason Harper's (anode drive) circuit, the voltage across his 1M (should be 10K, to speed it up) is clamped by the MPSA92 BE junction to 0.7V. That BE junction is in parallel to the resistor. On the MPSA42 side, its limited by the maximum excursion of the base excitation, which is the 5V coming out of the IO port. That again forms a maximum forward drops across the MPSA42's BE junction of 0.7V (again silicon), so the remainder or the drop across the 10K emitter resistor is 4.3V. 4.3V/10K is 430uA. 98% of that (assuming a hfe of 50) will go thru the collector-emitter path of the MPSA42. Only 2% thru the BE path. In engineering that's pretty much considered all of it, in this particular type of app. This part of the circuit is basically a current limiter, where the current out of the MPSA42 collector is mostly a function of the voltage across base to GROUND. NOT base to emitter. That BE voltage is fixed to 0.7V, unless the total voltage drops below 0.7V, then the collector current is zero. Remember that non-linear stuff again. When higher than 0.7V, the difference goes across the 10K resistor, and the current coming out of the collector is almost the same as the current thru the resistor, which is set by Ohms law. In reality, its a little fuzzier around voltages from 0.5V to ~1V. In this app, however, we apply only 0V (off) or 5V (on), so we're never in that fuzzy zone. rantIn engineering precision isn't always needed, and you round off when its convenient. Don't believe that crap you see on Star Trek and on digital calculators. The real world never gives you precision to begin with, so trying to get precision out of it, is mostly a futile effort. Yes, sometimes its needed, but mostly its not. In the modern industrial world we get precision in areas where its really not needed. That's mostly because of consistency. Its easier for a machine to make the same exact part all the time. If a square of toilet paper was another size, would world order break down ? Finally, don't believe me. Wire up the circuit for yourself, and take some measurements. All this writing is mostly toilet paper fodder. Its dogma, which is mostly crap. The essence of the 'Scientific Method' is the experiment. TRY IT OUT, and SEE WHAT YOU GET. That's why I get along with the likes of Westdave. He could care less about all this paper work. He just builds it and we all get to see the end results. Of course, in that process, a few parts get toasted, but that's all the fun part. Go out there and build something ! The magic of modern science, is not the body of knowledge that it has revealed, but the method upon which it was acquired./rant Wait... if I have a 10k resistor on the high side and a 10k resistor on the low side, won't the voltage at the base of the MPSA92 just hover around 85v? Is this low enough to turn it on? Also, 20k shorting between ground and +V and ground will draw 8.5mA, won't it? Also, I have a 1 megohm resistor between my base and emitter. Look at the bottom of page seven at: http://nixietube.info/NixieTransistors.pdf I'm well aware of that document. It was written by Jason Harper, a long time member of this group. I like his work, That 1M should be reduced to 10K. The voltage drop is limited by the maximum forward drop across the MPSA92s B-E junction, so it will only draw away 70uA at 10K, 0.7uA at 1M. ... -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
OK, I think I understood some of that. You're saying that the amount of current the MPSA42 will let through is defined by some relationship with (Vin-Vdrop)/Rground, or (5-.7)/1=.00043A. This is the amount of current across base to emitter, yes? But, if the Hfe is 50, doesn't that mean that I get up to 50*.00043A or .0215A across the collector to emitter? How did you get that 1/50th of that goes across the BE and 49/50 of that goes across the CE? Also, I really can't afford to just try stuff out. I have a limited supply of parts, which is why I carefully plan everything beforehand. On Jan 24, 1:15 pm, threeneurons threeneur...@yahoo.com wrote: No, No, No. That's only if there was no MPSA92 in the circuit. Remember, the Base- emitter junction of a transistor is a simple PN junction, ie a diode, and will act like one. The forward voltage will be limited to about 0.6V to 0.7V for your common silicon transistor. (Wiki a silicon diode) If the forward voltage is below 0.7V (for silicon), the base- emitter impedance is high, hence the need for that bleeder resistor, but when the voltage exceeds, or tries to exceed, that 0.7V 'knee', the impedance drops sharply (to close to zero ohms, ideally). Ohms law only works for linear components like resistors (AC or DC), and capacitors and inductors (AC only). PN junctions on semiconductors (diodes, including LEDs. and bipolar transistors) and gas filled tubes (nixies) are VERY non-linear. Think of them all as regulator diodes, that like one specific voltage to operate at. Of course, that voltage is different for each device. If that logic for 2 10Ks in series works. ie 190V supply and 85V across each 10K resistor, then with the 1M, there should be 188V across it and 2V across the other 10K. And it would, if you only had the 2 resistors, but you don't. In Jason Harper's (anode drive) circuit, the voltage across his 1M (should be 10K, to speed it up) is clamped by the MPSA92 BE junction to 0.7V. That BE junction is in parallel to the resistor. On the MPSA42 side, its limited by the maximum excursion of the base excitation, which is the 5V coming out of the IO port. That again forms a maximum forward drops across the MPSA42's BE junction of 0.7V (again silicon), so the remainder or the drop across the 10K emitter resistor is 4.3V. 4.3V/10K is 430uA. 98% of that (assuming a hfe of 50) will go thru the collector-emitter path of the MPSA42. Only 2% thru the BE path. In engineering that's pretty much considered all of it, in this particular type of app. This part of the circuit is basically a current limiter, where the current out of the MPSA42 collector is mostly a function of the voltage across base to GROUND. NOT base to emitter. That BE voltage is fixed to 0.7V, unless the total voltage drops below 0.7V, then the collector current is zero. Remember that non-linear stuff again. When higher than 0.7V, the difference goes across the 10K resistor, and the current coming out of the collector is almost the same as the current thru the resistor, which is set by Ohms law. In reality, its a little fuzzier around voltages from 0.5V to ~1V. In this app, however, we apply only 0V (off) or 5V (on), so we're never in that fuzzy zone. rantIn engineering precision isn't always needed, and you round off when its convenient. Don't believe that crap you see on Star Trek and on digital calculators. The real world never gives you precision to begin with, so trying to get precision out of it, is mostly a futile effort. Yes, sometimes its needed, but mostly its not. In the modern industrial world we get precision in areas where its really not needed. That's mostly because of consistency. Its easier for a machine to make the same exact part all the time. If a square of toilet paper was another size, would world order break down ? Finally, don't believe me. Wire up the circuit for yourself, and take some measurements. All this writing is mostly toilet paper fodder. Its dogma, which is mostly crap. The essence of the 'Scientific Method' is the experiment. TRY IT OUT, and SEE WHAT YOU GET. That's why I get along with the likes of Westdave. He could care less about all this paper work. He just builds it and we all get to see the end results. Of course, in that process, a few parts get toasted, but that's all the fun part. Go out there and build something ! The magic of modern science, is not the body of knowledge that it has revealed, but the method upon which it was acquired./rant Wait... if I have a 10k resistor on the high side and a 10k resistor on the low side, won't the voltage at the base of the MPSA92 just hover around 85v? Is this low enough to turn it on? Also, 20k shorting between ground and +V and ground will draw 8.5mA, won't it? Also, I have a 1 megohm resistor between my base and emitter. Look at the bottom of page seven at: http://nixietube.info/NixieTransistors.pdf I'm well aware
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Hi Will, I've learned more from trying and failing than I have from all of the great advice in the world. I've also learned that I can _actually_ do some things that everyone told me was impossible. Don't discount the merit of just giving it a shot. -Adam will wrote: Also, I really can't afford to just try stuff out. I have a limited supply of parts, which is why I carefully plan everything beforehand. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
OK then, tried it and it worked... I didn't notice a difference though... Still a little confused as to the properties of transistors, but I'll probably figure it out... On Jan 24, 4:57 pm, Adam Jacobs a...@jacobs.us wrote: Hi Will, I've learned more from trying and failing than I have from all of the great advice in the world. I've also learned that I can _actually_ do some things that everyone told me was impossible. Don't discount the merit of just giving it a shot. -Adam will wrote: Also, I really can't afford to just try stuff out. I have a limited supply of parts, which is why I carefully plan everything beforehand. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
I'd recommend studying something like this: http://mysite.du.edu/~etuttle/electron/elect2.htm Bill On Mon, Jan 24, 2011 at 7:38 PM, will ossumguyw...@gmail.com wrote: OK then, tried it and it worked... I didn't notice a difference though... Still a little confused as to the properties of transistors, but I'll probably figure it out... On Jan 24, 4:57 pm, Adam Jacobs a...@jacobs.us wrote: Hi Will, I've learned more from trying and failing than I have from all of the great advice in the world. I've also learned that I can _actually_ do some things that everyone told me was impossible. Don't discount the merit of just giving it a shot. -Adam will wrote: Also, I really can't afford to just try stuff out. I have a limited supply of parts, which is why I carefully plan everything beforehand. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.comneonixie-l%2bunsubscr...@googlegroups.com . For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
That's the stuff. I'm sure you will figure it out. We are almost always using transistors in these nixie clocks as saturated switches, almost never in the linear region or as amplifiers. You can spend years learning transistor theory, but that's not really necessary to turn on and off a nixie tube. A few test circuits, a glance at wikipedia, you'll be fine. -Adam will wrote: OK then, tried it and it worked... I didn't notice a difference though... Still a little confused as to the properties of transistors, but I'll probably figure it out... On Jan 24, 4:57 pm, Adam Jacobs a...@jacobs.us wrote: Hi Will, I've learned more from trying and failing than I have from all of the great advice in the world. I've also learned that I can _actually_ do some things that everyone told me was impossible. Don't discount the merit of just giving it a shot. -Adam will wrote: Also, I really can't afford to just try stuff out. I have a limited supply of parts, which is why I carefully plan everything beforehand. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
On Jan 24, 7:15 pm, threeneurons threeneur...@yahoo.com wrote: . If a square of toilet paper was another size, would world order break down ? No, but more extensive handwashing would be required :) Seriously though, I share Mike's general perspective. Learn from others the general principles of how the system works, estimate values within those guidelines(because near enough is usually good enough) and then experiment to refine your understanding or learn New Stuff. And the key to experimentation is that failure is usually more informative than success, so long as you take the time to think about why it didn't work (and in that process, Occam's Razor and Sherlock Holmes are your friends) Frankly, it's pretty difficult to acutely destroy a nixie as long as you have a controlled HV supply and a current limiting resistor in the right ballpark. You might shorten it's life, but it probably won't explode. Of course, microcontrollers expire pretty enthusiastically if you put the HV across them, but that's usually down to clumsiness rather than an unexpected design gotcha... Jon. PS. The relevant Sherlock Holmes quote is When you have eliminated the impossible, whatever remains, however improbable, must be the truth. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Err... I'm way past breadboards here, I thought I said that I was already multiplexing A1A lamps... By limited supply of parts I actually mean I don't want to keep shelling out to digikey, I've already spent too much for all this crap, not I don't have the basic parts, lol. I'm just more of a software guy, which is why I'm so clueless when it comes to specifics of transistors, inductors, and especially high voltage parts like nixies. Remember, all I ever use transistors for is cold, hard logic, no 170v craziness. The motion sensor, RTC, USART, shift registers etc. are the easy parts for me. Anyway, I thank everyone for helping me to understand this transistor stuff. I'm sure when I have some free time to think understanding will hit me. On Jan 24, 9:47 pm, threeneurons threeneur...@yahoo.com wrote: You should, at a minimum get the following: A small 'solderless breadboard': http://www.radioshack.com/product/index.jsp?productId=2734155http://www.mpja.com/prodinfo.asp?number=4443+TEhttp://www.allelectronics.com/make-a-store/item/PB-400/SOLDERLESS-BRE...http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2... I put a link to Radioshack in there, just because they're everywhere, which is really their only saving grace. That way you won't have to 'mail order' (dating myself) anything, if you don't want to. Don't try to build an entire system on one of these. Just use it to check out a circuit block, like that anode driver stage. Get a roll of 22AWG solid wire and a 9V battery clip, so you can use a 9V battery to power a test circuit. MPSA42s and MPSA92s are pretty cheap, but for trying out transistor concepts with any transistor. The PN and 2N3904 are commonly found NPNs, and can be substituted for the A42, as long as the supply is under 40V. Also a 2N3906 is a common PNP, and sub for the A92. Note, this is only to try out concepts. The other transistors won't handle nixie voltages. Back to the basic transistor lessons. In any bipolar transistor. One with a Base, Emitter, and Collector. Applies to both NPN PNP. The current out of the emitter is the sum of the base current and collector current. Lets place 5V at the base of that MPSA42 (NPN). The total drop from base to ground is that 5V. 0.7V will drop across the BE junction, therefore 4.3V has to be across that 10K resistor. By ohms law, the current is 4.3V/10K = 430uA. Now suppose your idea was true, and the collector current was 50 times (assuming an hfe ~50), that or 21.5mA. Then the emitter current is the sum of the base and collector, and then ~21.5mA. If that was true, the the drop across the 10K resistor would be 215V. If the transistor survived that, that means the emitter is 210V above the base; a reverse bias of 210V. The transistor would turn OFF. Not because it died (which it would), but because the forward current flow is no longer there. In that configuration, if the 10K resistor was the intended load, it would be called a 'emitter follower'. That means the emitter will follow the base. The voltage gain is roughly 1, or no voltage gain at all. Its used for current gain. But there's a real reason why the emitter follows the base, and its not just because the BE junction limits the voltage drop. At least not as a simple diode. As you raise the voltage at the base, from just under the the 'knee' of 0.7V (ideally) current starts to flow thru the BE junction. This will, in turn, cause a flow in current from C to E, by the factor of hfe, due to the physics of a bipolar transistor (don't ask me, I only use 'em, I don't design 'em). That's current 'Ib' coming into the base, current 'Ic' (=hfe*Ib) coming into the collector, and the summed current 'Ie' (=Ib+Ic=[hfe+1]*Ib) coming out of the emitter. This current, Ie, will cause a voltage drop across that 10K resistor. This is actually a negative feedback source, since as the resistor voltage rises, it lowers the drop across the BE junction. That will in turn reduce both Ib and Ic, hence lower Ie, and the resistor voltage drops. Like all negative feedback, this tends to balance things out, which magically is right at the 'knee' (0.7V across BE). The practical result is that the 10K resistor looks like a lot higher resistance at the base, by the factor of hfe+1, or 510K (assuming and hfe of 50). So get some parts, breadboard them up, and play a little. Since you only have a DVM, just use a wire to flip that base from 0V to +5V, or use a small trimpot, and watch the voltage track it. Start with just the NPN side, tying the collector to the positive supply. And just for fun and yucks adjust the supply voltage from 5V, to 9V, to 18V, to 27V, while keeping the base at 5V, and see what happens. Then rig the whole anode drive circuit. Instead of driving a nixie or neon, use a LED, and keep the voltage low (under 24V). Measure how all the differnt parts work. On Jan 24, 2:50 pm, will ossumguyw...@gmail.com wrote:
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
So then you already have a breadboard, that's good. You'll be along in no time. Being a software guy is no excuse, I'm a software guy. You can tell the software guys' circuits because all they are is the minimum hardware necessary to hook up the microcontroller... :D -Adam On Mon, Jan 24, 2011 at 9:08 PM, will ossumguyw...@gmail.com wrote: Err... I'm way past breadboards here, I thought I said that I was already multiplexing A1A lamps... By limited supply of parts I -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
I ran into the same problem with the 10's digit in the hour position. When it's dark, it takes extra time to turn back on. I put a 22 Meg resistor from the decimal point to ground. This primes the Nixie without turning on the DP (it glows very faintly), and it turns on without the delay. - Michael http://www.coldwarcreations.com ng characteristics depending on ambient light (ie how much they are pre- ionized). If I try to light up two lamps that share an anode, unless I have my desk lamp on, one of the lamps will fail to light for a second or so. I can actually control the activity of the lamps with a low- medium power (~15mW) blu-ray laser (high-energy 405nm photons). This -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Clever. One thing I was thinking of doing was putting a small ~400nm LED under the tubes and turning it on for a few microseconds while the tube started up, but your way is more sensible. On Jan 23, 9:53 am, M.J.Sangster mjs...@coldwarcreations.com wrote: I ran into the same problem with the 10's digit in the hour position. When it's dark, it takes extra time to turn back on. I put a 22 Meg resistor from the decimal point to ground. This primes the Nixie without turning on the DP (it glows very faintly), and it turns on without the delay. - Michael http://www.coldwarcreations.com ng characteristics depending on ambient light (ie how much they are pre- ionized). If I try to light up two lamps that share an anode, unless I have my desk lamp on, one of the lamps will fail to light for a second or so. I can actually control the activity of the lamps with a low- medium power (~15mW) blu-ray laser (high-energy 405nm photons). This -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Wait... if I have a 10k resistor on the high side and a 10k resistor on the low side, won't the voltage at the base of the MPSA92 just hover around 85v? Is this low enough to turn it on? Also, 20k shorting between ground and +V and ground will draw 8.5mA, won't it? On Jan 23, 2:45 pm, threeneurons threeneur...@yahoo.com wrote: Also, I have a 1 megohm resistor between my base and emitter. Look at the bottom of page seven at: http://nixietube.info/NixieTransistors.pdf A 10k resistor goes between the MPSA42 emitter and ground. I've been looking around craigslist for an old scope to buy, but nothing's really appealed to me. That new DSO quad digital mini-scope is actually really pretty nice (36ms/s) but I wish it was $100 like its relatively mediocre counterparts. On Jan 22, 4:25 pm, threeneurons threeneur...@yahoo.com wrote: I'm well aware of that document. It was written by Jason Harper, a long time member of this group. I like his work, That 1M should be reduced to 10K. The voltage drop is limited by the maximum forward drop across the MPSA92s B-E junction, so it will only draw away 70uA at 10K, 0.7uA at 1M. The 10K on the emitter leg of the MPSA42 limits the current from emitter to collector to Vcc-0.7V/ 10K, or ~430uA assuming a +5V supply. Most of that (360uA) will go thru the BE path of the MPSA92. Multiplied by the minimum hfe of 25, that means a max possible current to the nixie of 9mA. With a anode resistor limiting the actual current to under 3mA, this means the MPSA92 will be well into saturation, and voltage across its emitter to collector should be in the 0.5V territory, when ON. Also, the hfe will most likely be ~50, so it will even be more into saturation. The drop across the CE path of the MPSA42 will always be close to the full supply voltage, but the current will vary as a function of its BE excitation (the uC IO port signal). Max power dissipation will be ~80mW with a 180V supply. A TO92 case can handle around 350mW. My first scope was a Dumont 304R. I still have it. Dumont was the big name in o-scopes, before Tektronix arrived. Mr Dumont didn't think people needed the extra features a Tek scope had, so he didn't change his offerings. The 304 only has a 30KHz bandwidth, but it served me well. I upgraded to a 400 series Tek scope in the late 80s, which is my workhorse scope (40MHz). I also have a small Vellum handheld scope, which is always at ready, and handy for quick checks of signal integrity. The Dumont has been retired, but its too big to stick on eBay. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Yeah, after some development I've ended up using a completely different delay function that allows me to specify the amount of time on and off for the nixie. The minimum that works well is 50µs. It seems I miscalculated the time consumed by my last delay function. This also lets me set brightness from software and allows me to do fading effects very simply. However, I've run in to some cool things that probably won't end up actually being problems: 1.When the device is plugged in, even with the surge protector turned off, if I touch any of the neon lamps they light up a little bit (and if I touch them on the common cathode side, the other lamp lights up too). I feel no electrical sensation. This isn't really a concern, just cool. 2.I've been able to see this effect of the lamps changing characteristics depending on ambient light (ie how much they are pre- ionized). If I try to light up two lamps that share an anode, unless I have my desk lamp on, one of the lamps will fail to light for a second or so. I can actually control the activity of the lamps with a low- medium power (~15mW) blu-ray laser (high-energy 405nm photons). This could only end up being a concern if the same thing happens with the nixies and their comma indicators (which I intend to use). Also, I have a 1 megohm resistor between my base and emitter. Look at the bottom of page seven at http://nixietube.info/NixieTransistors.pdf for what I am using. A 10k resistor goes between the MPSA42 emitter and ground. I've been looking around craigslist for an old scope to buy, but nothing's really appealed to me. That new DSO quad digital mini-scope is actually really pretty nice (36ms/s) but I wish it was $100 like its relatively mediocre counterparts. On Jan 22, 4:25 pm, threeneurons threeneur...@yahoo.com wrote: On Jan 21, 3:58 pm, will ossumguyw...@gmail.com wrote: Yep, ... I needed to add what I believe was an extra 100 clock cycles (12.5us) or else the MPSA92s would stay partially on and allow just enough voltage to pass to cause an off bulb to flicker ... Now it's 100% contrast, no flickering at all. Very nice looking. 12.5uS is a tad on the quick side for nixies. You might want to add a little margin and double, if not quadruple it. I've used interdigit blanking intervals in the 50 to 200uS range, on my nixie projects. But then, I could be a bit anal in that respect. I haven't seen your anode drive circuit, but you should have a resistor across from base to emitter on those MPSA92s. They should be in the 10K to 22K range. They bleed off any charge across the base-emitter junction, which looks like an open circuit, when the forward drop, drops below 0.6V, and keeps MPSA92 ON a bit longer. A scope would be a good investment. There's been talk of cheap little digital scopes, lately, but you can get good used analog scopes for not much money. Shipping might be the biggest cost. Another thought is to build your own analog scope with little 2 3 CRT tubes that pop up on eBay often. You can use old scope manuals to find the schematics as your guide. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
I have built a clock with 6 IN-14 Nixies. I multiplex 3 sets of 2 nixies. I use 180v with 13K resistors with the following timing (the timing is conservative and works with 170v, too): Mux Timing: 1) turn on anode for current nixie(s) (data present on cathodes) wait 1880 uSec, this is the digit display time, small value will make the digit dimmer. 2) turn off all nixie anodes wait 96 uSec 3) send current digit data to nixies, wait 72 uSec, go to step (1) Works good, no ghosting and good brightness. Also, I use A1A's for colons with a 200K resistor. I use the anode (Nixie) switch for the colons so their brightness varies with the Nixies. See http://www.coldwarcreations.com/nixieclk3.html for more information. - Michael Sangster -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Thanks. My current timing scheme looks like this: 1.take a few µS to calculate values for shift registers 2.write bitshift registers (a few µs) 3.turn on the proper anode 4.wait 5ms 5.turn off anode 6.do steps 2-5 but for other tube 7.do steps 2-6 a few hundred times this works fine with A1A neons with a 100kohm resistor (200kohm makes them a bit sputtery). I'll take a look at your page. Now, my only concern is that my DMM only measures around 110 volts between the +voltage supply and the cathode transistors, even though there is 170v between +voltage and ground. I'll have to do some more testing, but it looks like for some reason the transistor collectors are hovering at about 50v... Maybe they just seem this way because of the PWM? On Jan 21, 9:20 am, M.J.Sangster mjs...@coldwarcreations.com wrote: I have built a clock with 6 IN-14 Nixies. I multiplex 3 sets of 2 nixies. I use 180v with 13K resistors with the following timing (the timing is conservative and works with 170v, too): Mux Timing: 1) turn on anode for current nixie(s) (data present on cathodes) wait 1880 uSec, this is the digit display time, small value will make the digit dimmer. 2) turn off all nixie anodes wait 96 uSec 3) send current digit data to nixies, wait 72 uSec, go to step (1) Works good, no ghosting and good brightness. Also, I use A1A's for colons with a 200K resistor. I use the anode (Nixie) switch for the colons so their brightness varies with the Nixies. Seehttp://www.coldwarcreations.com/nixieclk3.html for more information. - Michael Sangster -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
You would read a lower voltage because of the PWM, I believe it is an average value you are seeing. A scope would show the proper value. Or you could just slow down the PWM to maybe 2 seconds on, then your meter would show the proper value. - Michael Sangster On Jan 21, 12:00 pm, will ossumguyw...@gmail.com wrote: Now, my only concern is that my DMM only measures around 110 volts between the +voltage supply and the cathode transistors, even though there is 170v between +voltage and ground. I'll have to do some more testing, but it looks like for some reason the transistor collectors are hovering at about 50v... Maybe they just seem this way because of the PWM? -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Yeah, I'll do that as soon as I get home... I don't have a scope (yet). On Jan 21, 1:35 pm, M.J.Sangster mjs...@coldwarcreations.com wrote: You would read a lower voltage because of the PWM, I believe it is an average value you are seeing. A scope would show the proper value. Or you could just slow down the PWM to maybe 2 seconds on, then your meter would show the proper value. - Michael Sangster On Jan 21, 12:00 pm, will ossumguyw...@gmail.com wrote: Now, my only concern is that my DMM only measures around 110 volts between the +voltage supply and the cathode transistors, even though there is 170v between +voltage and ground. I'll have to do some more testing, but it looks like for some reason the transistor collectors are hovering at about 50v... Maybe they just seem this way because of the PWM? -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Yep, it was a combination of the multiplexing and a problem with the anode transistors. It turns out, having a small delay after turning off the anodes is important. I already had a few µs between turning the anodes off and back on for my shift register write functions, but I needed to add what I believe was an extra 100 clock cycles (12.5us) or else the MPSA92s would stay partially on and allow just enough voltage to pass to cause an off bulb to flicker during multiplexing and for the MPSA42s to register positive on my DMM. Now it's 100% contrast, no flickering at all. Very nice looking. On Jan 21, 1:35 pm, M.J.Sangster mjs...@coldwarcreations.com wrote: You would read a lower voltage because of the PWM, I believe it is an average value you are seeing. A scope would show the proper value. Or you could just slow down the PWM to maybe 2 seconds on, then your meter would show the proper value. - Michael Sangster On Jan 21, 12:00 pm, will ossumguyw...@gmail.com wrote: Now, my only concern is that my DMM only measures around 110 volts between the +voltage supply and the cathode transistors, even though there is 170v between +voltage and ground. I'll have to do some more testing, but it looks like for some reason the transistor collectors are hovering at about 50v... Maybe they just seem this way because of the PWM? -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
On Jan 19, 11:04 pm, David Forbes dfor...@dakotacom.net wrote: On 1/19/11 9:42 PM, will wrote: I'm building a nixie clock based off of four IN-14 tubes (currently in the mail from Russia). I'm multiplexing the tubes in groups of two, if it matters much. I've read all around for recommendations on anode resistor values to use, but they seem to change everywhere I go, and they are all for different supplies or situations (anywhere from 33kΩ on sphere's nixie tube page to around 10kΩ). Does anyone have any suggestions for my particular situation? Again, I built my power supply with feedback regulation, so it will be around 166-170v (that's as wide as I've seen it change). My priority is longevity, followed by brightness. Also, side note, can anyone recommend an anode resistor for an A1A neon lamp running off the same power supply? Those will provide various symbol indicators (colon, dash, degree sign, etc). You can calculate the anode resistor value once you know thrtee things: 1. Vp Power supply voltage 2. Vt Tube sustaining voltage 3. Ic Desired cathode current R = (Vp - Vt) / Ic So... what are good values for these? The makers of nixie tubes recommended at least 180V, since 160-170V is too low to strike the plasma consistently. You can measure the sustaining voltage by using a known value resistor (start with 10k ohms) and measuring the voltage across it when the tube is lit up. Use a variable resistor (a pot) and you can plot a curve of voltage vs current. For 2x multiplexing, use about 1.4 times the recommended cathode current for continuous use. That should get you there. -- David Forbes, Tucson AZhttp://www.cathodecorner.com/ Wait... sphere's nixie page says 170V and 33k. Is 180V 10k really reasonable? Also, is the purpose of the anode resistor not to decrease the voltage across the tube? Does the resistance of the tube decrease significantly when you energize it or something? What is a reasonable tube sustaining voltage for IN-14s? Reasonable current? Sorry for all the questions, this is just confusing to me. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
On 1/20/11 10:30 AM, will wrote: Wait... sphere's nixie page says 170V and 33k. Is 180V 10k really reasonable? Also, is the purpose of the anode resistor not to decrease the voltage across the tube? Does the resistance of the tube decrease significantly when you energize it or something? What is a reasonable tube sustaining voltage for IN-14s? Reasonable current? Sorry for all the questions, this is just confusing to me. A nixie tube is a constant voltage device, which means that the voltage across it is nearly the same over a wide range of current values. The current is controlled by the anode resistor. The sustaining voltage is not something you choose. The current is, and a reasonable value is specified in the data sheet for the tube. http://download.elektronicastynus.be/57/in-14_datasheet.pdf says that the maximum cathode current is 2.5 milliamperes. So you choose a resistor that produces a 2.5 milliampere current through it when driven by your power supply. Also, we typically do not measure the current directly, as it is more difficult since the meter must become part of the circuit. Instead, we measure the voltage and we know the resistance, then divide voltage by resistance to get current. -- David Forbes, Tucson AZ http://www.cathodecorner.com/ -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Think of the tubes acting a bit like a zener diode. [Or old-time valve regulators eg VR105 ] Same principle as fluorescent light tubes too for that matter. [And the reason for the Ballast] John K. - Original Message - From: will ossumguyw...@gmail.com Does the resistance of the tube decrease significantly when you energize it or something? -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
On 1/20/2011 12:47 PM, JohnK wrote: Think of the tubes acting a bit like a zener diode. [Or old-time valve regulators eg VR105 ] They have a strike voltage, considerably higher than the sustaining voltage. Before they ionize and start to flow current, you need the B+ voltage at least that high to get 'em to ionize. Then they act like a zener at the sustaining voltage. The resistor in question is sized to get the desired current at that fixed sustaining voltage. Same as any neon lamp. Same principle as fluorescent light tubes too for that matter. [And the reason for the Ballast] John K. - Original Message - From: will ossumguyw...@gmail.com Does the resistance of the tube decrease significantly when you energize it or something? -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Unfortunately, I've never used an old time valve regulator, a fluorescent light tube, or a zener diode. LOL. I feel so stupid when working with this kind of hardware... I'm now starting to think about it like this-if a higher value resistor is used, the current through the nixie decreases. This causes the resistance of the nixie to go up, which means that more voltage is dropped over the nixie, and this happens until it goes up to the sustaining voltage (but at a lower current). If a lower value resistor is used, more current goes through, and the resistance of the nixie drops until the voltage over it is its sustaining voltage (at a higher current). Is this inverse resistance-to-current relationship correct? That would make the most sense... but again, what is the rough sustaining voltage of the IN-14? Start-up voltage? I can set the boost driver to pretty much whatever I want (within reason). On Jan 20, 11:47 am, JohnK yend...@internode.on.net wrote: Think of the tubes acting a bit like a zener diode. [Or old-time valve regulators eg VR105 ] Same principle as fluorescent light tubes too for that matter. [And the reason for the Ballast] John K. - Original Message - From: will ossumguyw...@gmail.com Does the resistance of the tube decrease significantly when you energize it or something? -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Read the initial blurb here, around page 6: http://www.neazoi.com/technology/logic/GE-lamps.pdf Bill On 1/20/2011 1:58 PM, will wrote: Unfortunately, I've never used an old time valve regulator, a fluorescent light tube, or a zener diode. LOL. I feel so stupid when working with this kind of hardware... I'm now starting to think about it like this-if a higher value resistor is used, the current through the nixie decreases. This causes the resistance of the nixie to go up, which means that more voltage is dropped over the nixie, and this happens until it goes up to the sustaining voltage (but at a lower current). If a lower value resistor is used, more current goes through, and the resistance of the nixie drops until the voltage over it is its sustaining voltage (at a higher current). Is this inverse resistance-to-current relationship correct? That would make the most sense... but again, what is the rough sustaining voltage of the IN-14? Start-up voltage? I can set the boost driver to pretty much whatever I want (within reason). -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Yes, set it to 170VDC. Dieter Thanks... But again, what kind of voltage should I set the supply to? Many seemed to think that 170v was enough, but I guess not... -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Thanks... But again, what kind of voltage should I set the supply to? Many seemed to think that 170v was enough, but I guess not... I'd go at least 180V, maybe even higher (190V-200V). For a couple of reasons. One, your muxing it. Nixies don't turn-ON instantaneously. There is some turn-ON delay, which is a function of supply voltage. The higher the voltage, the quicker the neon ionizes. If you choose 170V or less, it might be just fine for a direct drive design. On a mux'd design you may experience some erratic behavior, and come back to us wondering why the tubes are flickering, even if you picked a total refresh frequency over 100Hz. Also, if you want to implement PWM dimming to do some fancy effects like cross fading, you want consistency, which a quick turn-ON time will give you. Turn-ON times, at 190V, is in the 20-40uS territory for standard size nixies. There's no period literature on this. I found out by running a few experiments, and reporting it back to this group. Reason two, the higher the supply voltage, the lesser will be the variation of anode current, with variation of the tubes inherent maintaining voltage. The maintaining voltage is usually between 130 to 150V. Say your using a 170V supply, and you design more the middle, 140V. Pick 2mA. 170V-140V=30V dropped across the anode resistor. 30V/2mA=15K resistor. If the one tube sets in at 130V, then it will draw (170V-130V)/15K = 2.7mA. Another tube set in at 150V, and it will draw (170V-150V)/15K = 1.3mA. That's a two to one variation. If you up the supply to 190V, and pick the same (hopeful) target spot of 140V, and 2mA. The anode resistor is (190V-140V)/2mA= 25K. Pick a 24K part. Again if a tube comes in at 130V, then the real current is (190V-130V)/24K = 2.5mA, and the other tube at 150V is (190V-150V)/24K = 1.7mA. The variation is reduced to ~50%. For 200V supply with all else being equal, the results are a 30K resistor, and anode current variation from 1.7mA to 2.3mA; 35%. In all cases, however, you are still in the operating specs of most standard size (0.5-0.6) tubes. That's why you can continue with your design and not wait til your tubes come in. Note big IN-18s should run at 4mA minimum. OT: The 'supply trick' also works with LED displays. And you'll get much better consistency going with a 12V supply over a 5V supply. I 1st did this in the early 80s with a mux'd 8 digit 7-seg display. Not only did I have to consider the variation of the forward drop of LEDs (equivalent to nixie's maintaining voltage), but also the variation in saturation voltage of both the anode and cathode drivers. At 5V, all those 0.2V 0.5V (and God forbid, 0.7V) drops add up. At nixie voltages, a half a volt, or even a volt or two, here and there, are no cause for alarm. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: recommendation for anode resistor for 2x2 multiplexed IN-14s @166-170v?
Good point... OK, looks like I might be increasing the voltage. Also, my A1A lamps came in the mail, I see now about the voltage holding effect. With a 100k ohm resistor it holds at about 60v, and with a 200k ohm it only drops to about 55. On Jan 20, 7:12 pm, threeneurons threeneur...@yahoo.com wrote: Thanks... But again, what kind of voltage should I set the supply to? Many seemed to think that 170v was enough, but I guess not... I'd go at least 180V, maybe even higher (190V-200V). For a couple of reasons. One, your muxing it. Nixies don't turn-ON instantaneously. There is some turn-ON delay, which is a function of supply voltage. The higher the voltage, the quicker the neon ionizes. If you choose 170V or less, it might be just fine for a direct drive design. On a mux'd design you may experience some erratic behavior, and come back to us wondering why the tubes are flickering, even if you picked a total refresh frequency over 100Hz. Also, if you want to implement PWM dimming to do some fancy effects like cross fading, you want consistency, which a quick turn-ON time will give you. Turn-ON times, at 190V, is in the 20-40uS territory for standard size nixies. There's no period literature on this. I found out by running a few experiments, and reporting it back to this group. Reason two, the higher the supply voltage, the lesser will be the variation of anode current, with variation of the tubes inherent maintaining voltage. The maintaining voltage is usually between 130 to 150V. Say your using a 170V supply, and you design more the middle, 140V. Pick 2mA. 170V-140V=30V dropped across the anode resistor. 30V/2mA=15K resistor. If the one tube sets in at 130V, then it will draw (170V-130V)/15K = 2.7mA. Another tube set in at 150V, and it will draw (170V-150V)/15K = 1.3mA. That's a two to one variation. If you up the supply to 190V, and pick the same (hopeful) target spot of 140V, and 2mA. The anode resistor is (190V-140V)/2mA= 25K. Pick a 24K part. Again if a tube comes in at 130V, then the real current is (190V-130V)/24K = 2.5mA, and the other tube at 150V is (190V-150V)/24K = 1.7mA. The variation is reduced to ~50%. For 200V supply with all else being equal, the results are a 30K resistor, and anode current variation from 1.7mA to 2.3mA; 35%. In all cases, however, you are still in the operating specs of most standard size (0.5-0.6) tubes. That's why you can continue with your design and not wait til your tubes come in. Note big IN-18s should run at 4mA minimum. OT: The 'supply trick' also works with LED displays. And you'll get much better consistency going with a 12V supply over a 5V supply. I 1st did this in the early 80s with a mux'd 8 digit 7-seg display. Not only did I have to consider the variation of the forward drop of LEDs (equivalent to nixie's maintaining voltage), but also the variation in saturation voltage of both the anode and cathode drivers. At 5V, all those 0.2V 0.5V (and God forbid, 0.7V) drops add up. At nixie voltages, a half a volt, or even a volt or two, here and there, are no cause for alarm. -- You received this message because you are subscribed to the Google Groups neonixie-l group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
