Pulse viewing in high voltage PSU, how to?

[neazoi]

Hello,
I consider this PSU **broken link removed**
I would like to find a way to monitor the pulses of the HV using a LED.
How should I connect a LED (possibly with a transistor driver?) at the output of U3, without affecting at all the pulse sent to the base of Q2?

 

[BradtheRad]

You could try putting a neon bulb near the 30 kV.
Proximity to either the bulb or the leads may be sufficient to light it.

I'm thinking of NE-2 or NE-2H, which used to be very popular.

 

[neazoi]

You could try putting a neon bulb near the 30 kV.
Proximity to either the bulb or the leads may be sufficient to light it.

I'm thinking of NE-2 or NE-2H, which used to be very popular.

Hm... I would not like to interfere with the output of the transformes, since it will affect the connected device operation (TEA laser). Wouldn't that it be simpler to use another NPN and drive a LED at the output of the 555? Do you think the current of the 555 would be enough to drive the new transistor as well as the power transistor?

 

[kam1787]

. Wouldn't that it be simpler to use another NPN and drive a LED at the output of the 555? Do you think the current of the 555 would be enough to drive the new transistor as well as the power transistor?

I did not do any calculations but I am quite sure that would be fine[555 can source 200mA], but I doubt you will see 'a' pulse - it will just be on. Given the caution about Q2 you might want to connect via cap to the collector of Q2