Found in an Electronics World of 1966 this circuit can be made with current power transistors. It causes colored lamps to flash to the rhythm of the audio signal applied to the input.
We can implement this filter with more modern equivalent operational amplifiers, since the LM110 is...
This stethoscope or amplifier for hearing aid using a crystal headset and microphone was found in a...
The normal use of a 4520 as a divide-by-16 counter is shown in Figure bellow. In the normal...