Project: 1.5V LED game

Thread Starter


Joined May 6, 2009
Perhaps a difficult one to explain, but I could do with some help understanding what's goin on in this working game :)

My idea, was to expand on the Joule Thief circuit (a circuit which allows a superbright LED to run from a single 1.2V rechargeable battery) to play a game.
I found a 'Signal Injector' circuit online here:
It uses 2 transistors, 3 resistors, 3 capacitors and I believe outputs a 0.5V square wave of high frequency. I was going to bring that frequency down and try to get the LED to flicker...similar to the Hallmark Galaga Christmas cab marquee you may have seen lol
But, I found out that if I grounded the Base connection of the second transistor, the light went off ! further, that 'sometimes' when the connection is Grounded again the light came back on !
The light would come on seemingly randomly, probably an exact timing condition and once in 8 connections or twice in 3 connections etc.
Aha I thought, game time. Try to light the light as many times as possible in 10 seconds.
Fitted a push switch to the grounding connection and there it was - first 1.5V LED game ;D
A game on Free Play..literally when solar powered, as successfully managed with another Joule Thief recently.

Why it confuses is because the Signal Injector stage is powered straight from the battery, not from the upped output of the Joule Thief. Different batteries do the same thing, so it's not a flaky battery or anything.
Now, I tested the 2N2222A transistor in the Joule Thief circuit and it switches off when that Ground connection is made. The output of the Signal Injector goes to the plus side of the LED. Is the Grounding to the Signal Injector stage passing back to the Joule Thief and simply switching it off ?

Schematics are the Signal Injector above, linked to a Joule Thief like this one:
Output of the Signal Injector to the plus of the LED. Signal Injector transistors are 9014's.

Here's the full circuit, which would fit in something the size of one of my micro arcade cabs that I build. Battery is from a dead cordless drill pack and is huge compared.