I got some IN-14 gas discharge tubes and I want them to live as long as possible. For that I need to dim them to the point that the digits just about to start to partially lose glow.
One way is to adjust the dropping resistor, which lowers the ignition voltage (~170V) to operation voltage (~120V). However this method is very sensitive to current (Ohm's law) and I need one digital pot for each tube.
Another way is to utilize the blanking function of the driver chip to PWM dim the tubes. However I have no idea what frequency is optimal for the tube lifespan.
I'd like to avoid audio frequency (32Hz-32KHz) and stay above "human eye frame rate" (some where 20-60Hz). High frequency is easily achievable but I wonder If this will shorten the lifespan as the tube ignites tens of thousands times per second.
Any insight on the frequency selection is much appreciated, or is it altogether a bad idea to dim the gas discharge tubes with PWM ?