...erm, not sure what you are referring to, there. Inductors are rated for their inductance (obviously!), and their peak current before saturation (also their DC resistance, "Q" factor, resonant frequency, etc., but those criteria will be less important in most smal SMPS power supply designs, as long as the inductance and current capacity are right). I have not seen an inductor rated in Watts before!
VERY rough calcs - Assume you want 180V out at 15 mA, that's 2.7W output power You'll be doing well if the design returns 80% efficiency, so that's 3.4 W input power Assume a 12V primary supply, so that's an AVERAGE draw of 300mA (I keep rounding the numbers) If the duty cycle of the driving transistor is 50%, (and the current is a linear ramp), then the PEAK current will be FOUR TIMES the average, so over 1Amp peak. If your chosen inductor can't handle that current, it will saturate; the circuit efficiency will drop and the inductor will get HOT. On Oct 11, 1:51 pm, Imbanon <[email protected]> wrote: > Many thanks for that explenation, I did not know how to read these. > I got my hands on a 100uH inductor of 0.5W for the circuit I posted. > Is that enough or should I get one with bigger wattage? > Thanks > > On Oct 9, 8:17 pm, "MrNixie (UK)" <[email protected]> > wrote: > > > > > > > > > That little simple "555" circuit is fairly standard and basic, and > > will work. It wont give top performance, but who cares? Stick closely > > to the advised components, particularity for the main FET, switching > > diode (NOT a IN4007 clone!) and inductor. Keep the layout reasonably > > compact. > > > DON'T touch the metal tab of the FET when it is running! I like the > > warning: > > > "enough energy to potential(LY?) kill a > > person should they be connected > > between the high voltage output > > and ground in the right way, so > > be careful when working on this > > circuit!" > > > I think they meant - "if connected in the WRONG way"! But the warning > > stands. > > > The Inductor in the other ready-made circuit I mentioned carries the > > number "221". This is the same as resistor coding, and in this case is > > the value in MicroHenries - 2, 2 and one zero; so 220uH. Anything in > > the range 100uH - 330uH will kinda work in these circuits, but needs > > to be able to handle the peak current, without saturating. > > > On Oct 9, 6:22 pm, daddyvan2005 <[email protected]> wrote: > > > > I bought one of these in the link above and like it. If Lance still sells > > > them. I use it for bench testing/proto work. It's adjustable which > > > makes it nice for certain apps. John Taylorwww.tayloredge.comhasareal > > > nice module that's pretty much plug and play and works real well also > > > adjustable. Koswww.kosbo.comalsosellsone. In all I found that having one > > > for the bench was required because once you start playing with neon your > > > hooked. Plus you should be checking those nixies before installing them > > > the be sure they actually work. > > > > ________________________________ > > > From: Imbanon <[email protected]> > > > To: neonixie-l <[email protected]> > > > Sent: Sunday, October 9, 2011 10:08 AM > > > Subject: [neonixie-l] Re: Disposable camera as power supply > > > > Thanks for your reply guys! > > > > And so I have gave up on my current supply, and decided to make my > > > own. I didn't want to make my own as I thought that it will be the > > > most expensive option, but I was wrong. > > > Seems like all these pre-made supplys are around 20 bucks, a bit less, > > > and for that kind of money I can make 5 of > > > thesehttp://www.ledsales.com.au/kits/nixie_supply.pdf,andstillhave a lot > > > of spare parts! > > > Does anyone have any experience with these? Are they alright? > > > Thanks again! > > > > On Oct 9, 6:25 pm, "MrNixie (UK)" > > > <[email protected]> > > > wrote: > > > > A couple of points. > > > > > > > > You are going to need more than 0.2-0.3 mA to fully light a nixie > > > > tube. Otherwise, you will see gaps in the numerals. > > > > > > > > A camera flash power supply has DREADFUL efficiency, is usually > > > > designed to work from a 1.5V battery, and does so by pulling HUGE > > > > currents - often over 1 amp. Here are the reasons why. > > > > > > > > Assume you need a 200V power supply, and at about 6 mA. That's > > > 1.2W > > > > out. The simple circuit found in cameras will be no better than 50% > > > > efficient, so that's at least 2W in. Even with a fully charged > > > > battery, that's 2/1.5 OVER ONE AMP in!! so you've got to > > > build a power > > > > supply capable of delivering over an amp, at one and a half volts, > > > > just to pamper to your camera circuit. Why bother? > > > > > > > > John points out several alternatives; I would further add that I have > > > > seen small custom-built power supply modules on eBay that will run > > > > from a much more convenient 12V or thereabouts, and return much > > > better > > > > efficiencies. If you are wary of building your own, then certainly > > > > look at one of these: > > > > > > > >http://www.ebay.co.uk/itm/NIXIE-TUBE-POWER-SUPPLY-MODULE-CLOCK-2-OUTP... > > > > > > > > ALSO! A camera flash power supply will be designed to charge a much > > > > larger capacitor (for the flash) than these custom supplies like the > > > > ones above, and this is capable of giving you a much bigger BELT when > > > > you put yourself across that open circuit 330V, than a smaller, > > > > current limited 180V supply. And, no matter how careful you are, > > > > sooner or later you will do this! Alas, I know this... :( > > > > > > > > Laurence (AKA MrNixie, UK) > > > > > > > > On Oct 9, 3:08 am, John Rehwinkel <[email protected]> wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I've just got my IN-14 tubes and started experimenting > > > on my first > > > > > > nixie project - the clock, of course! For now I am using a > > > disposable > > > > > > camera as my power supply. Shorted out with an amp meter, > > > it gives a > > > > > > steady 12.8mA at 330V, which is better than expected. > > > > > > > > > More accurately, it pushes 12.8mA through a short at zero > > > volts. I'm guessing > > > > > the 330V is no load. So in-between, you're getting less > > > than 330 volts at less > > > > > than 12.8mA. > > > > > > > > > > So my question is; should I continue bothering with this > > > power supply > > > > > > (should it even be used for 6 tubes) and try to fix my > > > schematics, or > > > > > > just make my own power supply which I am not so fond of. > > > > > > > > > I'm guessing the camera supply just isn't up to the > > > job, sad to say, but likely. > > > > > > > > > So there are a few ways you could proceed. If there are more > > > where that > > > > > came from, you could use six camera supplies, one for each > > > tube. That > > > > > might work, and would be amusing. Otherwise, you'd have to > > > come up > > > > > with the voltage some other way. The easiest way is probably > > > to buy a > > > > > ready-made supply like the Tayloredge ones. They're small, > > > reliable, and > > > > > very cost effective at $13 apiece, and you don't have to > > > make your own. > > > > > > > > > Alternatively, if you're using an AC supply, you can use a > > > transformer in > > > > > reverse to step-up the voltage, and rectify that. Three parts > > > (transformer, > > > > > diode, and capacitor) and you're there (you can steal the > > > capacitor and > > > > > probably the diode from the camera supply). > > > > > > > > > > Can driving nixies at such low voltage and current damage > > > my nixies? > > > > > > > > > Yes, running them underdriven like that can lead to cathode > > > poisoning. > > > > > It can be reversed, but it's disappointing when it happens. > > > > > > > > > - John KG4L > > > > -- > > > 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 > > > athttp://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]. 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