I want to somehow indicate(with LED diode for example) to user when vacuum tube is overdriven (When grid voltage is greater or equal than cathode voltage). My first idea was to connect a LED diode from grid to cathode, but I'm not sure if this is a good idea. LEDs have voltage drop of about 2V, and I need to detect if voltage is greater or equal.

  • 3
    \$\begingroup\$ I would suggest looking into comparators. The issue in your case will be the voltages involved - you will probably either want to float the detection circuit, or perhaps use big resistive dividers to lower the voltage. \$\endgroup\$
    – Joren Vaes
    May 13, 2020 at 8:04
  • \$\begingroup\$ You have micro-cap now (following yesterday's conversation) and this can be easily simulated with a comparator. \$\endgroup\$
    – Andy aka
    May 13, 2020 at 9:36


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