Suggested by General Electric in a 1965 publication this circuit uses a light bulb. Can be changed to use LED and capacitor can be 22 uF.
We found this configuration of band rejector filter or band rejector with operational 741 in a...
This oscillator can use any CMOS inverter. The circuit is crystal controlled and was found in the...
This circuit was found in a 1967 US documentation. It shows how to build a gain control by digital...