This is a combined circuit of tone generator and preamplifier. We found it in a 1975 documentation. Operational amplifiers of that time can be replaced by modern equivalents.
With this circuit it is possible to obtain a voltage of 24 V using a 12 V regulator. The maximum...
We found this circuit in a 1965 publication by General Electric. The zener is 8.2 V x 1 W and the...
This circuit was found in a Hands On Electronics from the 90s. It turns on an LED to indicate that...