This is a super powerful little circuit when playing an online game that logs you out of the game after not sensing any key strokes for a minute or two. Being I put this circuit in Wii shaped mint tin I called it the Wii Wand of Power.
It’s just a simple timing circuit made of discreet elements that engages a reed relay ever 25 sec. This relay in turn closes a circuit in my keyboard for the left arrow key. Being this external circuit is self powered I can simply turn it on when I want a game or application to think I’m at my computer when I’m not. I know there are software hacks that can do this and I did try a lot of them but this particular on line game I play had a way to block such software hacks. I had to go old school, which is not hard for an old guy, and do it with hardware.
The trick is getting a connection to a key in your keyboard and using a plug of some kind that can be removed so you don’t always have extra wires hanging out of you keyboard. I used an old mono audio jack for my connection to the keyboard.
Most everything in this build is made from salvaged parts. My son’s candy tin, an old discarded mono audio jack plug and receptacle, the switch from a broken digital thermostat control and even the perf-board was cut from the corner of an older project. You get the picture, don’t throw out old electronics because they have the best reusable parts! And hot glue! That stuff is so damn handy.
I have used this timing circuit may times over the past 20 years. It’s cheep, stable, configerable, isolated from the circuit you’re controlling and can run for months on a couple of AA batteries. The circuit is based off an original published in Forrest M. Mims III notebooks. Not a bad little circuit for a few cents when there is no need for microcontroller over kill :)
You have to open your keyboard and follow the traces for a button of your choice.
The flex keyboard button traces will all converge back at a small PCB and you should be able to see where the traces you were tracking pickup on the PCB. Verify that you found a working trace using your multi-meter set to continuity checking. In my case when the left arrow key was pressed I would get a short between these two traces on the PCB and the meter would buzz.
I scraped off the green trace insulator over the two traces I found for my left arrow key and soldered two short wire wrap leads to the exposed traces.
This wire wrap goes back to a mono audio jack plug I drilled into the back of my keyboard where there was some free space.
Leave just a little extra wire wrap so you can open and close your keyboard without pulling the wires off the traces.
Put the keyboard back together and you’re ready to jack in your Wii Wand of Power.
When you turn it on your game character will rotate to the left every 25 seconds when you’re getting a sandwich or picking the kids up at the bus stop. :)
This is the circuit. You can play with the cap and resistors for a faster or slower delay. Just about any PNP and NPN transistor will work in the two positions and I used a Radio Shack SPST Reed Relay rated at 3-5V at 20mA and 240 ohms.