This circuit is from the 1983 Intersil Databook. The circuit has an A / D converter for display of 4 and a half digits being powered by a voltage of 9 V.
This circuit activates an LED, but it can be modified to activate a relay. The time is set in VR1,...
A divide-by-4 or two-bit binary counter can also be built using two flip-flops of the 4027 type as...
This two-channel DC volume control uses a transconductance operational amplifier. The transistors can be...