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 from an Electronics World of 1967. The circuit slows down the activation of a...
Found in a 90s Popular Electronics, this circuit is intended for amplifying analog video signals....
Found in Popular Electronics, this configuration can be powered by voltages from 6 to 12 V....