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.
Other amplifiers of the series like the MC3301, MC3401 and LM2900 can be used in this circuit. We found...
We found this balanced modulator circuit for DSB and possibly SSB transmissions in US 1980s...
Found in documentation from the 1980s, this converter or inverter circuit uses components from...