I’ve always wanted a timer for, say, turning off Christmas lights after I’m in bed, or to shut off the battery charger after an hour. Like a big kitchen timer attached to a light switch. So when I found this in a scrap pile it’s use and purpose in life were obvious – unlike many of the other things I have collected. Thing Timer! Not just for eggs anymore.
Behold, shiney giver of electrons! This is one of those projects that had been kicking around in the back of the cranium for a while and came together all at once, mostly by accident. First, in the summer (of ’05) my cousin’s laptop power brick was deemed useless for it’s intended purpose when it caught fire because the ground wire frayed totally and made sparks. I was commissioned to get rid of said power brick. And the following Spring (’06) I took a metalworking class and was required to make a box. Perfecto chronologium. (No, that’s not actual latin for “good timing”.) Continue reading
I ran across the idea (and the schematic) over on a page that seems not to exist anymore, and which was run by a guy named Mike Torchia. (Here’s the archive.org link, as long as that still exists.)
Anyway, I often have needed to switch quickly from a good drive to a lighter distortion and rolling down the volume knob on my guitar is a nusiance – never mind imprecise – and this thing essentially does the same thing with a stomp switch. Here’s the schematic (from Mike’s page):
The capacitor across the pot allows higher frequencies to continue making your sound sparkle instead of loosing all that treble, like when you turn down the volume knob on the guitar. I have mine turned down a lot to give a lighter drive instead of my normal distortion and it’s a little finicky to set, but I think I may have used a linear taper pot instead of log taper. Ues log tapers for audio, folks!
Yep, that’s all I did. I had extra AT power supplies kicking around and needed more (i.e., didn’t have any) good 12V bench power supply, so I stuck in a switch, banana jacks, a 10-ohm stabilizing resistor, and finished it just in time to spend a few weeks running my Grandmother-in-law’s LCD monitor until she got a new one after the power brick croaked.
But now I have it back and can document it.
I started with an AT power supply because I had a couple kicking around; this particular model is a 230W from Sparkle Industries. Switching is easier with these than with ATX supplies, I just hacked in a big DPST power switch and I was ready to rock. Or Toggle. No parasitic power drain, no extra transistor thingy to make it work.
As you can see the wiring is a little messy. For 5V and ground posts I crammed three or four of the wires into a crimp terminal. The binding posts, handily, have extra nuts on the back end which are perfect for spade lugs.
The 12V line is a female disconnect that just fit on the solder tab for that jack. I also had to jump the fan power from there, the original 5V fan had been copped for something else.
I used a 10Ω, TO-220 load resistor on the 5V rail to stabilize the output like everyone says to. You can see I just screwed it to the case (photo 3) and it works great. Make sure the tab is isolated from the leads before you do the same thing.
The power light you can see in photo four. It’s just the warm glow of an LED stuffed in where it would light things up, without drilling another hole in the case.
And rubber feet complete the build with dignity.