This tester was found in a 90’s Popular Electronics. The integrated circuit is CMOS 4011. The indication is made through LED.
It can be obtained from Mouser Electronics, sensors (receivers) transmitters and benders for...
Suggested by General Electric in a 1965 documentation, this circuit can use the TIC106 as an SCR....
The circuit shown is from the 1994 Linear Applications Handbook from National Semiconductor. The...