Small size High-Voltage regulated inverter

There are several scenarios where a small size inverter is required. Running circuits with vintage Nixie tubes on batteries, or building Geiger counters, the inverters are widely used for these cases and more. In this article I’ll show a new design based on the MC34063 ic, a ferrite choke and an active pull down mechanism, very similar to the one presented here.
The pull down allows discharging the switching transistor’s base/gate charge much faster, than using only a simple resistor. But this works only when swinging down. Swinging up things work like without the active pull down part. Efficiency can be as good as 80%.
The circuit:
MC34063_ferrite_inverter-sch MC34063_ferrite_inverter-brd
For 5V in, the circuit output is a little more than 200V . The output is regulated, and you can adjust the output voltage by changing the R5 value.
For 3V in we get less, but enough to turn on a neon bulb, like shown in the first picture, where I used a 3V lithium cell to power the circuit.

To get as high as 400V, the voltage used by most Geiger tubes, some minor changes are required, but one can easily take this circuit as a starting point.

Download the Eagle files here:

This article has 7 Comments

  1. Salut, schema publicata de tine este foarte utila, felicitari!
    Vreau sa te intreb cateva chestii. Incerc sa construiesc un ceas cu nixie-uri si ma incapatanez sa pastrez o singura tensiune de 5v pentru logica si pentru circuitul de tensiune inalta. Poti sa imi spui cam ce curent iti da circuitul tau? Nu ma intereseaza sa fie smd componentele, am destul loc in cutie. De asemenea ce tranzistor ai folosit pentru partea de pull-down? eu incerc acum cu un bc327 cu o dioda 4148 sa golesc mai repede poarta unui mosfet, dar dupa 5 minute mi se incalzeste foarte tare bc327.Ceva sfaturi?
    Multumesc in avans pentru ajutor!

  2. the link to eagle files doesnt appear to work. no problem as i only have through-hole components available.

    switching transistor(s) unspecified? basically any high speed low rfs should do, i gather…

    i guess i can just increase a few resistors to cope with 12v input, ditto to alter output voltage.

    otherwise…neat 🙂

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