The purpose of this circuit is to indicate which of the two cars crosses the finish line first on a slot car lane. The circuit is from an 80's Popular Electronics.
This circuit was found in a 1992 publication, using an operational amplifier not very common...
This is a amplifier for XTAL high impedance earphones or piezoelectric types. Current drain is...
This circuit is from the LM111 manual of the 1980s. The component no longer exists, but...