[sdiy] OT- Battery powered HV supply?

[Paddock, Toby]

Thanks everyone, this really is where the good answers are.
Toby

> 
> I finished a little blinky neon bulb project and I found 
> the current draw is lower than I expected. 20uA at 300V. 
> So now I'm wondering about a low current battery powered 
> supply.
> Toby

Grant Richter wrote:
> 
> Look inside any disposable camera with a flash unit. 
> There is a little PCB that charges up a photoflash cap to 
> 300 volts.
> I got this from sci.hacks for cheap fast 300 volt supply. 
> Be careful! 300 volts, even just in a cap, is enough to 
> bite you pretty good!
> 
Nice! I'll keep my eyes open for some of these. 

Anthony wrote:
> 
> Plug them all into each other. That looks cool.
> Really it's easy to make a battery powered HV supply 
> using CMOS gates as oscialltors and then running the 
> output through a diode/capacitor voltage multiplier. 
> Just pick a multiplier that'll give you the volts you need.
> I don't have a link off-hand, but I could draw up a 
> schematic maybe...
> Getting it to be low current might be tricky. This 
> technique is easiest for voltages around 100...
> 
I love this idea. A hex Schmidt trigger chip gave me about 100V, but the
current was kind of high, just like you say. It was 14mA with no load, seems
awful high. But that chip had been abused, so maybe that's the reason. I
figured I could get about +/- 150V out of 3 hex schmidts and something like
36 caps and 36 diodes. But I ran out of time and went with the back to back
xfmrs.

Harry wrote:
> If you don't need mains isolation... I'd use one of 
> those little "Flatpack" transformers of any size... 
> with the primary windings connected as autotransformer.
> 
> (so 120V in = 240V out) then rectify that.   If you 
> don't care about ripple you could filter with a film 
> cap, giving a long, safe operating life 
> 
I do need mains isolation in this case. But even if I didn't, I wouldn't
have thought of using a single xfmr as autotransformer. Excellent! 

Mike wrote:
> Very good low power HV supply can be made using a 
> CMOS 555 timer with a PNP transistor  switch, use one 
> of the tiny HV transformers from a disposible camera 
> with built-in photoflash (also contains a HV
> rectifier). Set it up so the timer produces very brief 
> (low duty cycle) negative-going spikes  at around 
> 100 Hz rate.   ...
> Run on 2.5 to 3 volts ...  Easy to get 500 to 1000V 
> this way. ... battery drain lower limit is around 
> 400 microamps at 3V  (the timer chip alone takes 
> around 150 uA). 

This has everything going for it and fits my vague 
notion of what I need. CMOS 555, xfmr I don't have 
to figure out and build, low tweakable duty cycle. 
Perfect.

Monty Brandenberg wrote:
> 100V should be enough to ionize which puts you 
> in the range of the little EL backlight 
> dc-to-dc converters.

I do need 300V for this because there are relaxation 
oscillators in series, but that would be great for 
some other blinkys or tube stuff.

Here's some pix of my blink-o-grid:
http://www.seanet.com/~tpaddock/public/imuf08m.jpg
http://www.seanet.com/~tpaddock/public/imuf08cm.jpg

Later,
Toby