This interesting circuit uses a sodion valve that we have already described in an article on the website. The circuit uses several batteries for power. The phone is of high impedance.
In a bistable circuit, as shown in the figure, we use two sensors. When one of them is touched, the...
This is a second circuit that we found in a French documentation from 1981. See the previous...
This multivibrator circuit uses only one gate and its frequency is controlled by the crystal. The...