This circuit was found in an Elektor from the 90s. Transistors are common and status indications are made through LEDs.
This is the receiving circuit for the transmitter given in the previous circuit. The circuit is...
Found in an Electronic Design from the 80s, this circuit generates a 500 Hz signal and can be used...
It is a common version but with components calculated for a frequency of 1 kHz. The circuit shown...