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 was found in the ON Semiconductor's Thyristor manual of the 1980s. The high quality...
This simple injector circuit can actually be powered by voltages from 3 to 9 V. The frequency is...
This 10 kHz filter is based on a 741 operational amplifier. The circuit is from Electronics Now...