![]() 1 LED and 1k resistor (optional, LED not pictured). The switch portion of the relay needs to have a decently high current rating since we will be running AC current directly through here to the device we want to power. ![]() The coil voltage should match the regulator voltage. ![]() With the 1000uF cap, mine will run for about 2.5 hours. This pot will allow for adjusting the timer. The large electrolytic will be used to run the timer, so the bigger it is, the longer your max time can be. 3 capacitors: 1 0.01uF (103) ceramic disc 1 470uF electrolytic 1 large electrolytic. You can also get a bridge rectifier if you want, since that is what we are going to build. 1 2N3904 bipolar junction transistor, or BJT. You also don't want a 7909 regulator as it will provide -9VDC, which you don't want. You can use whatever regulator you have so long as it matches the DC input rating on your relay switch. 1 fuse rated for slightly less than the relay max current rating. You can also solder directly to the copper pads but it may not be as secure. board pins as needed/desired for connecting AC lines. We don't need a grounded cable here, so 2 wires will do fine. This one came with the AC power cable attached to the transformer and is used to secure the cable to the housing. You can find these on the back of DVD players, home theater systems, and VCRs. We want an output of about 12-15VAC, but if your outlet supplies 220VAC, it will still work. Any transformer that has a step down factor of 10 will work here. a 2N2222 NPN BJT instead of the 2N3904 listed. Also, many times the exact part is not absolutely required, just something that is compatible, e.g. That being said, none of the parts are expensive, so it shouldn't be hard to come across them if need be. Most parts are still useful as long as you take care in how you remove them from the original board. I salvage what I need/want from whatever device I can get my hands on. Also, don't burn yourself with the soldering iron. We will be working directly with AC mains voltage, so BE EXTREMELY CAREFUL!! Make sure that any time you are testing the circuit, you have your work space clear and anyone around you is aware of the danger.
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