Using PWM to dim NCS314 bulbs

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This topic contains 1 reply, has 2 voices, and was last updated by  Doridian 5 years, 8 months ago.

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  • 14.07.2018 at 22:05 #7757

    sutton57
    Participant

    Is it possible to use PWM in order to dim the bulbs? If so, would this be done on the DHVpin pin that controls the MAX1771 Driver Hight Voltage(DHV)?

    If so, do you have any PWM duty cycle recommendations?

    04.09.2018 at 12:57 #9809

    Doridian
    Participant

    I am currently running an NCM109, which, due to multiplexing, only allows each segment to be on 1/3rd of the time.
    But, since I also have a “fade” effect to transition between numbers, even lower duty cycles should be possible.
    To be precise on timing, without fade effect, I turn on a Nixie for 2ms, then off for 4ms using an interrupt timer (there is blanking intervals in between of 0.2ms each, but those aren’t necessary for your use-case at all).
    Due to multiplexing, of course, I also do this by Anode voltage (as the Cathodes are all tied together).
    If the DHV pin is actually a functional element on your Nixie, you can try working with it (but according to information I found online, you should not turn on a Nixie for less than ~1ms, so if you PWM on that, make sure it fits that), however I’d still recommend using the HV switch (the one you control with SPI) and not PWMing the supply.
    However, I found out, on my NCM109 the DHV pin is just a relic from other firmwares that doesn’t actually turn on or off anything.

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