This circuit triggers an LED when the input signal exceeds the peak, or the value set in RV1. The transistors can be the modern equivalents BC549.
Found in Ferranti's 1968 documentation, this circuit uses a Darlington photo transistor to drive a...
Found in documentation from the 70s, this circuit uses components from that time. Some of these...
This circuit monitors the state of a 12 V battery and can be used directly with one, or even in a...