This circuit triggers by choosing the higher of two voltages. The circuit is from a 1964 Electronic Design. The transistors are of the time and can be replaced by current equivalents.
The circuit shown timing the drive of a motor using an optical coupler. The diode bridge can be...
This circuit with power MOSFETs was found in a 1980s Siliconix documentation. Equivalent MOSFETs...
June 2017 - The new touch switches C & K KXT series can now be obtained from Mouser Electronics. These...