Found in 90s Radio Electronics, this small transmitter has a good range. L1 is formed by 3 + 3 turns of wire 24 around a pencil as a reference.
This circuit makes use of a sensitive 5 mA reed-relay to be driven directly by a phototransistor. The...
An integrated circuit 741 (operational amplifier is the basis of this voltage indicator, which can also...
This circuit was obtained from an English magazine from 1976. The signal from the circuit should be...