This tester was found in a 90’s Popular Electronics. The integrated circuit is CMOS 4011. The indication is made through LED.
This circuit was found in a 1965 General Electric documentation. SCRs and unijunction may be...
The BA1404 integrated circuit (not very easy to obtain) consists of a complete stereo FM...
This circuit is from a Radio Electronics documentation from July 1959. In this documentation the...