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Simplest form of relay enabling delay. There is a simpler way, where you add the relay directly to the emitter, but this method is unreliable and can lead to further complications. For instance I made the simpler topology for my tube amp and sometimes the relay partially latches, until full driving voltage is acquired at the coil, which causes the contacts to arc a little (due to the high voltage it controls, and the not so good contact it makes) and I expect it to wear out or weld shut pretty soon if I don't modify the driving circuit. With this circuit, the first transistor drives the second one more abruptly into saturation, which enables the relay quicker, and will probably not have the partially enabling problem I have right now. The circuit itself draws no more than 15mA, which at 12V gives a total dissipation of 180mW, which is well within the ratings of any low power transistor. P.S. The circuit is designed for the relay I have, and the dissipation value is meant to go with it. It well vary with different relays.
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