[sdiy] OT- Battery powered HV supply?

[John L Marshall]

Toby,

While looking for LEDs in the Mouser catalog, I saw "inverters for 
fluorescent lamps".

Take care,
John

Pacific Northwest Synth Meeting September 25, 2004
----- Original Message ----- 
From: "Paddock, Toby" <tpaddock at seanet.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, January 23, 2005 10:45 PM
Subject: RE: [sdiy] OT- Battery powered HV supply?


> 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
>