Low temperature sensor (CB7814E)

Found in 90s Radio Electronics, this circuit is indicated for reading temperatures below zero.

500 Hz neon generator (CB9079E)
This circuit generates 500 Hz rectangular signals. The circuit is from old American documentation. Neon...
Tunnel Diode and Transistor Oscillator (CB1340E )
The circuit shown is a documentation on 80's tunnel diodes. The frequency depends on the delay line...
Amplifier LM386 with Pre 741 (CB18632E)
In the figure we have a small general-purpose amplifier with the LM386 integrated circuit and...