Suggested by a Popular Electronics from the 90s, this circuit triggers an external load, relay or recorder, when the telephone line receives a call, thus enabling its recording.
Figure bellow shows how the flip-flops of a 4027 can be connected to perform a divide-by-5 counter [odd...
This circuit for a simple alarm system was suggested in an article in Electronics Now magazine. The...
This circuit is based on a common cathode 7-segment display. The circuit is based on CMOS...