This circuit is from a 1969 General Electric manual. The SCR may be the TIC106. Similar circuits from other sources are found on this website.
In the figure we show how to trigger a triac for a continuous voltage of the order of 2 V,...
This 2005 Linear Technology circuit has separate outputs for monitoring the charge and discharge...
This circuit was obtained in a June 1987 magazine Hands-On. It is a circuit that indicates on two...