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.
A small voltage-boosting transformer is used in this pulse generator circuit found in...
This circuit was found in a 1964 magazine, which no longer exists. It is a small wireless...
This circuit was found in a 1980 documentation. The triac used is of the TIC226D type which in the...