Found in a Popular Electronics from the 90's, this circuit detects the approach of objects by the reflection of the radiation emitted by the LED. The relay is a 12 V sensitive type.
Found in a 1964 Electronic Design, this circuit generates pulses based on an avalanche diode of...
This circuit generates sinusoidal and cosine signals of 2 kHz given basically by the values of C1...
This circuit produces low frequency sinusoidal signals. The circuit is a phase shift oscillator...