This telephone circuit was found on a 90's EDN. It keeps a flashing LED to indicate that there was a call in your absence. The components admit equivalents.
Found in an American publication from 1968, this circuit generates pulses at a rate of 2,500 per...
The transistors on this circuit can be the BC548. The circuit is from English documentation from...
In the figure we have a stereo decoder from the 70's with pilot lamp for signal indication. The...