This optical counter was found in a 1964 Electronics Design. It makes use of an uncommon optocoupler today, using emission lamp and a phototransistor.
This non-inverting AC amplifier was found on a Popular Electronics. The setting applies to any...
This basic configuration of an astable multivibrator was found in a publication of the year 1968....
Suggested to power the previous circuit, this power supply was found in the December 1990 issue of...