Using a MAX644 this circuit was found in the April 1989 issue of Radio Electronics magazine. The circuit is for a 5 V voltage and 50 mA current output.
January 2017 - Mouser Electronics already has the new PMO Sonalert microphone elements from...
This configuration makes use of an LM3900 transconductance operational amplifier. The transistor can...
SST LLE Series Liquid Level Sensor Switches Available through Mouser Electronics, these solid...