All Transistor HV Neon Supply (simple)

[dom444]

I wanted an easy to make High Voltage supply for neon and tube circuits so I came up with this compact adjustable and easy to make all transistor supply works down to 5V.
the coil is important and value shown works well, it works at 6KHZ with the capacitors shown.

there is an error on schematic capacitors are 33n not 100n

 

[c_mitra]

These neons do not need really high voltage and they can work with very little current. So the power demand is rather low.

Once the neon conducts, the capacitor C3 will fully discharge because the on resistance is rather low. Hence the lamp will act like a flasher with the same frequency as the multivibrator. You can safely reduce the C3 value to a smaller one without any visible effect.

 

[dom444]

no problem i just used what i had in junk bin rated at 400v at 6khz can't notice any flickering but be careful setting the pot almost burnt the neon lamp when i had a dry joint on the feedback transistor base. i had no control over the output.

 

[FvM]

Voltage control doesn't make sense for glow-discharge lamp load which has almost constant operation voltage with negative differential resistance. And you surely don't operate the inverter circuit in constant voltage mode, you are rather reducing the output current by driving the switch transistor into linear mode, with respective power dissipation.

 

[c_mitra]

1. The flickering will not be visible;

2. You can reduce the value of C3 to 1-10nF range (to reduce the surge current when the neon conducts) OR

3. Use a series resistor with the lamp that will reduce the surge current and also remove the flicker

4. The coil is loosely wound; wind it tightly.