This amplifier for playback of recordings was found in a 1947 manual. It uses a push-pull output with a tube power supply.
Found in Popular Electronics from the 1980s, this circuit is intended for switching filters with...
The BA1404 integrated circuit (not very easy to obtain) consists of a complete stereo FM...
This transmitter uses an electret microphone and has a few tens of meters in range. The coil L1 is...