The L1 coil is formed by 4 turns of wire 20 in the form of 0.5 to 0.6 cm without core. The circuit is from an 80's documentation. The range reaches a few tens of meters.
This crystal-controlled oscillator was found in the January 1994 issue of Electronics Now. Other...
Found in old documentation, this timer uses a sensitive relay and a 2N2646. The time is given by...
When S1 is closed, the L1 lamp turns on and the L2 lamp turns off. The circuit is powered...