Found in an Electronic Design from the 80's, this circuit uses components from that time. He has outputs for activating 8 solenoids from a microcontroller.
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...