We found this circuit in a Popular Electronics of the 90s. The circuit can be easily mounted today, as the components are common. The SCR can be the TIC106.
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...