Freeze Alarm (CB14454E)

The circuit of a 1968 publication can be implemented with more modern transistors such as BC548 for NPN and BC558 for PNP.

Dynamic Noise Limiter (CB12194E)
The LED is optically coupled to the LDR1 sensor to provide negative feedback to the circuit and...
Simple ohmmeter (CB4152E)
The idea of this circuit is a resistance meter or continuity test with a common microammeter or...
Constant Current Source (CB12175E)
This selectable constant current source was found in an English publication in 1983. The...