This circuit, found in a 1977 documentation, indicates when the grid voltage goes through zero. Under these conditions, it produces an output pulse whose duration depends on the capacitor.
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...