This small source for low consumption projects was found in an old national documentation. The transistor is for general use and the transformer has 50 to 100 mA of secondary current.
This powerful alarm circuit was found in the July 1975 issue of Radio Electronics magazine. The...
In many applications involving control of circuits from the power grid, the zero-pass detector is a key...
In this circuit the LED remains on after pressing S, for a time that depends on the capacitor...