This circuit was found in a 73 amateur radio magazine from the 90s. An LED extends the scale from 0 to 5 V to 10 to 15 V in this bargraph circuit. Other zener values can be used.
We found this circuit in a 1968 Electronics World. The transistors are from the era and...
In the figure we have the way to implement a monostable with an operational amplifier LM393. The...
Suggested by Motorola documentation from the 1980s, this circuit makes use of MOSFETs of the time....