If you’re like me, you’ve left a soldering iron plugged in once or twice. Hopefully you’re also lucky like me and it’s never started a fire. Occasionally I’ll grab something off our Hack Rack and take it apart. A) It’s fun and B) it helps cut down on the ever-growing pile of appliances in the East Room. Recently I focused my efforts on a microwave oven. During my salvage operation I managed to extract one plastic fan, two thermal cutout switches, a transformer, the magnetron, a huge capacitor, and the controls. I soon realized that what I had in front of me was a digital timer wired to a normally open relay. I couldn’t immediately think of something to do with it, but it seemed too good to toss or disassemble further. About a week later I decided to wire it to a pair of 120-volt receptacles. Voila. Any appliance with a standard plug can be set to run from 00:01 to 99:99 before powering off. Just press “TIME COOK” then enter the time in minutes and seconds, then start. The relay closes the circuit and the outlets are energized. When the timer runs out, a piezo buzzes and the outlets shut off. The relay on the microwave’s circuit board is 120-250 volt at 16 amps, so I’m fairly comfortable it will handle one or two 40-watt soldering irons.
MaCoστις I’ve been trying to do soihtemng like this myself, but I couldn’t manage it to work.I had an idea to use 555, but didn’t exactly know how. I’ll try to do it myself, and I’ll write if I suceeded. For now thank you very much for fine tutorial :) M