Why does it have to be 555 or MAX1771? Nobody ever gives the MC34063 any love. ;)
Calculate your anode resistor with a single tube on, direct drive. (Make the software just turn on one tube and leave it on).. Calculate that current to be 2.5ma Now, put the same anode resistor on all the IN-14's. :) Simple. You _can_ put more current into nixies when they are multiplexed, it makes them brighter but reduces their lifespan. -Adam On Sat, Aug 6, 2011 at 11:44 PM, Ryan McDonald <[email protected]>wrote: > Well, I was going to build the 555 using the plans at > www.ledsales.com.au/kits/nixie_supply.pdf which calls for a IRF740. I > noticed that the MAX1771 plans always call for a IRF830 or a > IRF644PBF. If I build the 555 would I be better off swapping the > IRF740 for a IFR830 or IRF644PBF? Or are the 555 plans tuned to the > IRF740. I'm absolutely not against building with the 1771, but I > guess Im scared of reports of its instablity if not done *exactly* > right. I do understand the fundamentals of a switchmode supply but I > do not understand them well enough to debug and tune them with a > scope. The 555 seems more "forgiving". Does anyone know what the > output specs are of the 555 design are anyway? I've never seen them > stated. > > Is it correct to say that the only way to purposely dim the tubes is > to use PWM on the tubes themselves (and not use PWM in the HVPS to > reduce V or C)? I totally get uC's and digital logic but V/C > considerations are not my strength. Am I correct in saying that a > tube will attempt to draw too much current if directly connected to > the HVPS (even if the HVPS is running at the correct V) and the anode > resistor prevent this (while also requiring a V adjustment to get the > V *and* C correct simultaneously?) > > > I completely understand the IN-14 datasheet when it says the current > is 2ma for the tubes in direct mode, but can someone check my head > about what the datasheet means when it says "Average current for > digits 0.7 - 1.5mA" and "Pulse current for digits 7 – 13mA". I take > this to mean literally what it says (during the "on time" of a mux, > current is 7-13 and the average current is .7 to 1.5). In mux mode, > how would I go about measuring the current using a scope (I have a > fairly decent 20mhz analog scope I use for logic analysis) and/or > multimeter. Why is it ok to drive a mux at 7 to 13 ma "pulse > current", when the tube is rated at no more than 3.5ma? I do > understand the duty cycle aspect here but it still seems that during > the "on time" of the mux, we are nailing the tube VERY hard (well > above it's direct drive specs). I'm concerned that my ignorance about > V/C is going to cause me to run my tubes too hard and cause sputter/ > poisoning. > > I would really appreciate some of you veterans helping about a > newb. :) BTW, I will post my BASCOM-WWVB code soon. It turned out > really nice! > > -Ryan > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To post to this group, send an email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > 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 [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
