This circuit was found in a 1971s English magazine. We can still assemble it using BC548 transistor. The other components are common. The supply voltage of 6 or 12 V depends only on the relay.
Found in a 1970 documentation, this circuit makes use of 741 operational amplifiers that are...
We found this automotive alarm circuit in a 90's Popular Electronics circuit. The circuit emits a...
This circuit source a voltage proportional to the number of the input pulses. The circuit has a...