This circuit is part of an integrated circuit tester published in an article in Radio Electronics magazine in September 1985. The circuit is powered by a 9 to 12 V source.
This circuit appears elsewhere on this site, but from different sources. Using the LM3900, we find this...
This interesting source or isolation transformer also allows to vary the output voltage by...
In this circuit the CA3140, an operational amplifier, is used as a comparator with the zener diode...