This 6-transistor circuit had excellent sensitivity using germanium transistors. The push-pull stage used two transformers, one drive and one output as we usually find at the time.
Written in an article in Radio Electronics magazine in April 1987, this circuit triggers an alarm...
This is the receiver circuit for the previous transmitter. The circuit has a programming key to...
This is an example of a temperature sensor shield using the Texas Instruments TMP390 obtained from...