We found this circuit in the October 1988 Radio Electronics magazine. The circuit is still current due to the components used, and changes can be made.
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...