Author Topic: Simple adjustable PSU for NIXIE tubes  (Read 623 times)

Offline Mars

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Simple adjustable PSU for NIXIE tubes
« on: November 19, 2019, 06:01:12 PM »
Hi All

I am building an adjustable PSU for IN-6 tubes so the light brightness can be adjusted. Can anyone check this design and correct me if I got something wrong?

Power requirements:

Working voltage: 150V-170V;
Working current: 2.5 mA.

I design for 10 tubes, thus 25mA

This is what I propose. I think I'll heatsink the TIP50 for safety.



Will it work?
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Offline Den123

Re: Simple adjustable PSU for NIXIE tubes
« Reply #1 on: November 19, 2019, 06:43:46 PM »
You are going to have nearly 240V DC on the collector, so it will”bless you” right out of your socks if you touch it!

Offline Mars

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Re: Simple adjustable PSU for NIXIE tubes
« Reply #2 on: November 20, 2019, 10:25:29 AM »
You are right! I will probably add some resistors in series to drop die DC to 160V.
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Offline Nchebe

Re: Simple adjustable PSU for NIXIE tubes
« Reply #3 on: November 20, 2019, 12:12:26 PM »
You are going to have nearly 240V DC on the collector,

Yup! Also, the resistor divider (250k-10k) won't divide the voltage when wiper is right at the 'top' of the pot, thus putting the full DC voltage on the output.  A 100k resistor between + and 'top' of pot should limit you to around 160V, else get a transformer with a 115V secondary rating to limit output voltage (VDC=1.4 X VAC)

Offline Mars

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Re: Simple adjustable PSU for NIXIE tubes
« Reply #4 on: November 20, 2019, 05:13:40 PM »
I decided to keep the design simple.



The results were good. Only 1W dissipation (at idle) on the 10K wirewound pot and an adjustable 154V to 75V on the output.

Hopefully this will do the job.
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Offline fredeb

Re: Simple adjustable PSU for NIXIE tubes
« Reply #5 on: November 20, 2019, 06:55:35 PM »
Interesting watching you develop your adjustable circuit Karel . I'm busy playing around with different resistor values on the PSU for my phonostage to see the difference at different operating points , this adjustable circuit would've been handy to quickly find the right operating point . :)
...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
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Offline Den123

Re: Simple adjustable PSU for NIXIE tubes
« Reply #6 on: November 21, 2019, 06:19:55 PM »
Ag. I am an idiot! I forgot. Karl, look at the LR8 chip from Microchip. Linear voltage regulator. 1.2 - 438V. TO92 package, so low power. Built in current and temperature regulation. Really nice find. Not expensive either.

Offline handsome

Re: Simple adjustable PSU for NIXIE tubes
« Reply #7 on: November 21, 2019, 09:46:31 PM »
LR8 doesnt do a lot of current. nixie tubes are display tubes they dont need a super accurate or clean supply so something basic like karel has done is cheap n easy