This optically coupled circuit was found in the February 1968 Radio Electronics magazine. The circuit uses an LDR in modulation. Transistors are types of the time.
We found this circuit in a 1979s British publication. The circuit can be assembled with more...
This simple digital frequency meter using CMOS circuits reaches 5 MHz frequency. Input signals are...
This 16-second voice recording circuit was featured in a telephone answering machine circuit in...