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I made neon tubes glow with an inverter transformer and blocking oscillation

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The blocking oscillation circuit is a simple high-voltage generator circuit that can be made using only a transformer, transistor, and resistor.

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Circuit diagram


The circuit looks like this. Very simple, isn't it?

For the transformer, I used the one removed from the inverter board. I used a tester to find out where the connections are.

Trying to change various transistors


The neon tube lit up with only 1V. This is amazing.

Yellow is the voltage of the transistor, and light blue is the output of the transformer. 1V generates about 200V.


I thought that if the transistor could carry more current, the neon tube would glow brighter, so I changed the transistor to a Darlington transistor, which can carry more current.

The Darlington transistor has two stages of transistors, so it has a high gain and can carry a lot of current. However, it requires twice the normal voltage to turn on, so the power supply voltage needs to be about 2V.

By using Darlington transistors, the light seems to be a little brighter.


I changed to MOS-FETs so that more current could flow. This is probably due to the higher ON voltage compared to transistors.

The output voltage is also a little higher.

High voltage can be obtained easily

The blocking oscillation can easily produce high voltage AC.

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