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[on:]

I got some disposable camera guts for my Nixie Tube clock per this tutorial:
http://www.instructables.com/id/Disposibal-Camera-Nixie-Tube-Driver/

The thing is, I plan on running my clock off 5V. So if the camera transformer converts 1.5V to 200+V then 5V would result in 666V, right? That's bad.

I don't want to buy an expensive prefabricated nixie tube driver. I figured I could use a potentiometer to get the 5v to 1.5v but then I'm going 5V > 1.5V > 200V > 170V and using two potentiometers and that seems silly. Does anyone have any suggestions on how I should do this?

Thanks

[Reply #1 on:]

You will not be able to use a potentiometer to provide a stable voltage to power the unit since the pot output will collapse due to current draw.  A pot can only be effectively used to provide voltage at zero current.  I'd suggest trying to find a voltage convertor chip capable of running off the 5 volt system and providing the 1.5 you require.  Yes it is down-up-down but that's life.   
An even cheaper way might be to fit a 3.5 volt zener diode in series with your 5 volt supply line to the camera module.  This will drop the 5 down to 1.5 volts.  However the zener will probably need to be rated at say 1 watt minimum in order to handle the required current draw.
jack

[Reply #2 on:]

Okay that sounds good. How would i go about finding this particular voltage converter chip? A quick google search turns up a lot of different things.

[Reply #3 on:]

the lm2575 is good if you want a switching regulator. or you could use an lm317

[Reply #4 on:]

I'm just trying to further explore my options... Would finding a 5V to approx. 170V transformer be possible? It's hard to find anything other than consimer electronics on google. Is a specific step up transformer something that a person can buy online?

[Reply #5 on:]

Try looking into guitar tube amplifier tranformers.
They usually take in 120v AC and out 6-7v volts at higher current for the tube 'heater's, along with higher voltages for the tube gain stage.
You should be able to go the other way as well.

Hmm, but you have 5VDC - and transformers run on AC.

So you need a DC-DC converter. Or do the Nixie tubes  need 170V AC?

Supply some more info please.

[Reply #6 on:]

check out
http://www.hammondmfg.com/5cindex.htm
Once you get your AC & DC requirements worked out, these guys have lots of varieties, can work on a distributor after you find a part that will fit your needs.

[Reply #7 on:]

ehh... I figured a different transformer would be easier but it's not looking that way. I think ill go with the lm317. Thanks guys.

[Reply #8 on:]

Okay, I got the lm317, and Ive got it down it 1.5v with a 220 and 47ohm resistor. It is producing the correct voltage when i test it with a multimeter, but when i hook it up to my transformer, it drops to less than a volt, and my transformer hisses at a very high frequency.... any advice?

[Reply #9 on:]

You need a couple of capacitors on its output, say 0.1uF and 100uF in parallel.  One takes out HF noise and the other LF noise.  Within the current capabilities of the chip, the output voltage should be reasonably independent of the current draw, so it's probably the oscillation of the output that is giving you the "1 volt"
jack

[Reply #10 on:]

Thanks. I'll give this a try soon

[Reply #11 on:]

Wait, the output of the regulator, or the transistor?

[Reply #12 on:]

Regulator.
Check out a datasheet
http://www.national.com/ds/LM/LM117.pdf
They all show a cap on input & output.