This circuit was found in a Radio Electronics from 1970. The coupler with LDR is from that time, but the circuit can be adapted to use modern components and act as a shield.
With a light pulse on the Q1 sensor the circuit turns on and locks. To switch off, a light pulse...
March 2017 - STMicrocoelectronics' new LoRaWan B-L072Z-LRWAN1 STM32 development board can now be...
This circuit is from the manual of the components used, from the 80s. The circuit is valid for...