This circuit appeared in Radio Elecronics magazine in 1968. The operating circuit is a general-purpose type at the time and the power supply must be symmetrical.
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...