Ultrasonic Proximity Sensor (CB21312E)

This circuit was found in a Popular Electronics from the 90s. The circuit uses a ceramic capsule as an emitter and detector.

Limiter Amplifier (CB12468E)
This amplifier for effects on musical instruments can be mounted with BC549 transistors. The...
RF Oscillator LM3909 (CB14292E)
We found this circuit in documentation from National Semiconductor. For the medium wave range the...
Insect Repellent (CB6888E)
According to what is said, the bugs are the female insects (mosquitoes, muriçocas and others)....