Trying to draw up an Arduino compatible nixie cloc

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7 years 9 months ago - 7 years 9 months ago #2973 by the_dude
Hi, I'm planning on building several nixie clocks (I have ZM1020, IN-18 and IN-17 tubes) and right now I'm planning the control circuit.

I have taken the design from lots of sources online and I would love to get some pointers.

Last edit: 7 years 9 months ago by the_dude.

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7 years 9 months ago - 7 years 9 months ago #2974 by bcoggs
Looks like it'll work. Trust you've looked at my AtMEGA 328-based driver board schematics - cogwheelcircuitworks.com/downloadables/NixieDisp7971x4-B/ That design uses HV513s for the drivers. They are costly and if I had it to do over again, I'd take the approach I'm taking with my soon-to-be-released nixie shield - cogwheelcircuitworks.com/projects/nixie-...rduino-nixie-shield/ I don't have the schematics posted for that yet, but it uses the same pnp-pnp anode drivers and 2 74164 shift registers. For the cathode drivers I use some 75468s. I'll attach the Eagle .sch file

..c
www.cogwheelcircuitworks.com
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Last edit: 7 years 9 months ago by bcoggs.

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7 years 9 months ago #2975 by the_dude
Thanks for posting your schematic! Those are always very helpful. Are you trying to compete with arduinix.com ? I was not familiar with your design.

May I ask why you're not using the K1551d? What about the resistors for the MPSA42/92 transistors, why are you using 47K/470K, does it make a difference I have only 10K/1M there? I have hundreds of 10K resistors lying around :)

Am I correct you're using PWM on the AVR to generate high voltage?

I'm still struggling with the AVR and pin layout. I'm thinking about throwing in a 74hc595 shift register for the anode side to free up pins, so I can add a buzzer and an NTC and just to have pins available for hacking. Is that the same road you're taking with the 74164? I'm not familiar with that chip.

I'm also dabbling with the idea to hook up the neons to the sqw/out pin of the RTC. Has anybody done that? It frees up a pin and once the RTC is setup, you can stop writing code for it.

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7 years 9 months ago #2976 by bcoggs
K1551d i don't know about.
Values on the resistors not critical.
My anode resistor (4k) might seem low, but I do current control through multiplexing and pwm hv control from the pic (yes that's how I do it).

Not trying to compete with arduinix.com, just providing another option. I think theirs suffer from lack of code. I'll be providing tons of code.

Yes the '164s are just serial in parallel out shift registers. definitely the way to go to save pins.

Like your buttons on resistors w/staggered values.
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7 years 9 months ago #2977 by the_dude

bcoggs wrote: K1551d i don't know about.
Values on the resistors not critical.
My anode resistor (4k) might seem low, but I do current control through multiplexing and pwm hv control from the pic (yes that's how I do it).
.


I don't see how you can do current control through multiplexing. Once the tubes are lit, their resistance drops.
Shouldn't you raise the voltage on the tubes (to reduce striking time), rather than decrease the anode resistors when you're multiplexing? That's what I read in the datasheets, although I'm not entirely sure what the best voltages and PWM frequencies are.

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