This circuit was found in an Elektor from the 90s. Next to the circuit we have a table with the delays obtained when the circuit is connected according to the positions of the selector switches.
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...