# Safe inverter circuit to power neon indicators

I bought some neon indicators from eBay. I want to find a safe way to power them so we can do some experiments on solderless breadboards.

I can obviously power them from mains (120VAC/60HZ USA), but that's not safe for handling on a solderless breadboard. :)

I built the following circuit from parts lying around. At 12VDC input I get 150V pulses at 140Hz, <1% duty cycle. Obviously this only causes one electrode in the neon tube to illuminate.

Two questions:

1. How dangerous would this circuit be in comparison to 120VAC mains? I realize this unit's maximum current output would be orders of magnitude less than mains...

2. Is there a simpler, better circuit that doesn't require hard-to-source components like inductors and opamps? Full-swing AC output would be preferred from a 9VDC battery: something kids could build without me worrying they would electrocute themselves.

I seem to recall Forrest T. Mims illustrated a simple high voltage output circuit with just a couple components, but I can't find it.

Easily sourceable components for this project include resistors, capacitors and general purpose transistors, as well as diodes, LEDs... We also have a few wall-wart transformers we could tear apart if needed.

simulate this circuit – Schematic created using CircuitLab

• Where are you in this world that opamps are hard to source? Sep 2, 2016 at 0:20
• Sorry, I should have said "not in my junk box" haha. I have some on order from eBay but I was trying to make this out of as few discrete components as possible. (It's a learning experience!) :) I could have used a 555 to generate the pulses but wanted to learn how to build the simplest possible oscillator out of discretes. Sep 2, 2016 at 0:23
• So if your primary criterion is "breadboard-friendly", why use the neon bulbs at all, rather than the much simpler to drive LEDs? Sep 2, 2016 at 1:20
• It is a learning exercise. Neon bulbs are cool. You can do unusual things like create oscillators etc with them. I want to demo these features safely on a breadboard and give other people the opportunity to try it also, with the simplest and least expensive/easiest to obtain parts. Sep 2, 2016 at 1:24
• I think it's the DC aspect that causes just one electrode to glow. You might try a push/pull topology, or some kind of A/C. Nov 28, 2020 at 21:43