Found in an English publication in 1969, this circuit has a 600 kHz pass band. Ferranti's transistors support modern equivalents.
When the input voltage exceeds the value set in R4, the LED lights up, indicating this. The...
In this circuit of the 80's components of the time are used. The circuit controls a direct current...
Found in a 90s Elektor, this circuit is based on a Maxim integrated circuit of the time. The...