The figure shows how to use an 8080 in a digital to analog converter. The circuit is from a Radio Electronics from February 1978. The other components are from that time, except for the TTL.
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...