I have soldered a negative ion generator. And it has a neon lamp (GT-NE6S1325T) as a discharge speed indicator at the output side. The setup looks like this:

enter image description here

The idea is when the capacitor accumulates enough charge (90+ V) it goes through neon bulb. The neon lamp does blink as the electrodes on the left discharge negative charge into air. It blinks faster in damp weather or when I bring hand closer to electrodes.

With current setup the interval between blinks is too high ~8-10 seconds or it gives very dim constant light (no blinks) when I bring hand closer.

How can I increase the blink speed to make it more noticeable. And I want to make sure it blinks (i.e. no constant dim glow when discharge is faster).

  1. Should I decrease the capacitance. What value would be ideal? 10 nF?
  2. Or, should I decrease capacitor rated voltage from 630 to 400 or 240 V?
  3. Or, should I decrease 1 MΩ safety resistor's value?
  4. Or, what other change or new components are required in the circuit?

Also, if I want to reduce the blink rate in rainy seasons. How can I make blinks adjustable without hampering the device performance much? A potentiometer in series with the capacitor?

  • 1
    \$\begingroup\$ 1M resistor + 10kV power supply + "bring hand closer" = 10mA current.... isn't this incredibly dangerous? \$\endgroup\$ Commented Apr 24, 2023 at 10:23
  • \$\begingroup\$ @DanielChisholm I didn't mean almost touching. 4 inch+ is sufficient to feel the air breeze. I use incense stick to go any closer and to see the air flow. \$\endgroup\$
    – the Hutt
    Commented Apr 24, 2023 at 10:56

1 Answer 1


A smaller capacitor would make it blink faster. You can calculate/simulate what de value should be but if you have the components laying around I would just try it out. A high voltage trough a high value resistor is nearly a constant current source. So you can assume that a capacitor half the capacity will charge about twice as fast.

Changing the voltage rating of the capacitor will not do anything. Its just the maximum voltage before the capacitor breaks.

Decreasing the value of the resistor would also work but this will increase the discharge current, witch may or may not be desirable.

If the flashes are very bright but too fast, you can slow them down by putting a resistor on series with the neon lamp. It will make the flashes dimmer tho.

Edit - as a response to a comment, 10kV is only dangerous when the power supply can sustain this voltage under load. Then 10mA will flow and that is deadly.

  • \$\begingroup\$ The smaller capacitor indeed increased the blink rate. But the lamp glows much dimmer than before now. \$\endgroup\$
    – the Hutt
    Commented Apr 29, 2023 at 11:15

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