We found this CMOS circuit in a 1978 publication. It allows you to use a standard calculator keyboard with 16 keys for encoding in hexadecimal.
This circuit is from Popular Electronics from the 90's. The circuit discharges the battery with a...
We found this time base circuit in a timer project from the August 1972 Radio Electronics...
This sonic switch, vox or sonic relay uses a Darlington of the time that has a gain of 10,000. The...