This circuit uses a resonant reed switch at the trigger frequency. The circuit is from General Electric in a 1966 documentation. This type of component is rare today.
The gain for this circuit is given by the ratio between R2 and R1. The circuit is suggested by...
This receiver is from European documentation from the 90s. The integrated circuit is uncommon, and the coil...
Found in a 1970 EEE, this circuit can be applied to TTL ports. The supply is 5 V and the...