In this interesting circuit from Popular Electronics, the output voltage is the square root of the input voltage. Equivalent operational amplifiers can be tried out.
This traditional crystal CMOS oscillator circuit was found in a 1990 Electronics Handbook. The...
This version of a call-fish is from 1981 using, for this reason, a 90 V battery that is no longer...
This signal strength meter (S-meter) was found in a 1975 amateur radio publication. We can use...