Proximity Sensor (T291E)

This is a circuit from a 1977 documentation. R1 is 39k, R2 15k, R3 3k9 and C1 uF. The tube is the critical component of the project.

Voltage Limiter (CB4245E)
This circuit, which appears elsewhere in this section but from other sources, was found in a book...
Long Timing for the 555 (CB4575E)
In the figure we have a circuit where two 555 operating one as astable and the other as monostable...
Synthesizer Amplifier (CB1491S)
This circuit is intended for signal amplification of electronic musical instruments. We found in a...