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.
This circuit is an improvement of the previous circuit. An input resistor must be included...
This low frequency astable multivibrator use two probes in the simulation. The probes ar found in...
This circuit, suggested by a 1975 documentation, detects an electrical discharge in a storm by...