Found in an Elektor from the 90s, this circuit is suitable for viewing audio signals on an oscilloscope. The operational amplifier admits equivalent.
This circuit was found in an old Popular Electronics. With it we can check the operation of a...
This circuit triggers a relay when the set temperature is reached. The circuit is from an old...
Suggested by General Electric in a 1965 publication this circuit uses a light bulb. Can be changed...