This shield circuit is from a 1968s Motorola documentation. The relay is according to the supply voltage. R1 can be reduced to lower trigger voltages.
Found in American documentation from the 90s, this CMOS circuit detects the source of a signal and can...
This circuit is from a 1964 Electronic Design. The transistors are from that time. They can be...
This circuit was found in 1960s Radio Electronics. The circuit uses components from that time. The...