This circuit is from a Radio Electronics from March 1970. The integrated circuit used is one of the first for this purpose, being improved later leading to types that succeeded it.
A constant current source can be built based on one of the LM3900 or LM2900 amplifiers, as shown in...
This circuit was found in a 1973’s Japanese magazine. It uses transistors of the time and is...
We found this circuit in a 1980s General Electric documentation. It appears from other sources in this...