I am going to put a pair of 2 digit displays on my amp chassis for the volume readout for each channel. I noticed there is driver chips that decode binary and drive the tubes. Why is this necessary or is it? I was planning on making a circuit board that goes behind the volume knob with two pads patterned in an array that coincides with the steps in my volume switch and put a beryllium copper contact tab on the back of the volume knob that bridges the 2 rows of pads and use that to send the b+ to the nixie tubes. Any reason what I plan isn't a good idea other than having the voltage right there where you touch the amp. I can make it so that is safe. I could drive relays off a 5 volt signal as well. But is there any reason I would want the driver chip?
You need to switch 180V, a 74141 has 10 high voltage switches to gnd. You could also do that with 10 transistors (BF259) or relais.
If you want 2 digits (0-99) you have to create a BCD anyway.
Input from a pot coupled to the volume knob creating a linear voltage ramp and with an 8bit A/D converter in the PIC for higher resolution.
A rotary encoder has usually only 15 steps per rotation
You can do that with an Arduino or similar. How to control a Nixie Tube with Arduino – idyl.io
If you want 2 digits (0-99) you have to create a BCD anyway.
Input from a pot coupled to the volume knob creating a linear voltage ramp and with an 8bit A/D converter in the PIC for higher resolution.
A rotary encoder has usually only 15 steps per rotation
You can do that with an Arduino or similar. How to control a Nixie Tube with Arduino – idyl.io
Ok but why all that? when I can just switch the voltage direct to the tube? I am asking btw.
And as for two tubes I just run two traces from the pad receiving the power, one to each tube element.
And as for two tubes I just run two traces from the pad receiving the power, one to each tube element.
It can indeed be simple. A nixie tube just requires a high voltage supply with a current limiting resistor to the anode, and then switch the appropriate cathode to ground to get it to display.
If your volume switch has say 24 outputs, and you want to drive 2 tubes you can do that with one layer only by combining the digits with 2 diodes BAV21 so you only need 48 per pair. makes each contact independent.
the cathodes (marked) to the switch contact and the switch common to gnd.
https://www.taiwansemi.com/assets/uploads/datasheet/BAV19%20SERIES_E1610.pdf
digi-key has them
the cathodes (marked) to the switch contact and the switch common to gnd.
https://www.taiwansemi.com/assets/uploads/datasheet/BAV19%20SERIES_E1610.pdf
digi-key has them
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I have a Nixie tube clock you can look at for guidance on how to drive the tubes. I use 74HC595 shift registers to control all the cathodes and anodes connected to MPSA42/MPSA92 transistors.
GitHub - profdc9/NixieClock: A Nixie clock that uses IN-14 tubes and very generic components that can be easily sourced.
It also includes the power supply, schematics, and source code.
GitHub - profdc9/NixieClock: A Nixie clock that uses IN-14 tubes and very generic components that can be easily sourced.
It also includes the power supply, schematics, and source code.
If you go the computer route, connect a potentiometer to the volume knob and use it as a voltage divider to produce a 0-3.3V or 0-5V output, depending on the computer's logic levels. Use this as an analog input to an Arduino's analog to digital converter. Its 0-1023 value can then be used to decide which output pin to turn on which will control the Nixie tube cathodes through MPSA42 transistors.
The Arduino Mega 2560 has lots of output pins so shift registers are not needed. This will simplify the programming.
The Arduino Mega 2560 has lots of output pins so shift registers are not needed. This will simplify the programming.
