It is a 13.8 V x 10 A regulator obtained in a 2008 documentation. The 2N3055 transistors must be mounted in excellent heat sinks and the voltage is adjusted in the trimpot.
We found this simple frequency meter for low frequencies in an English publication from 1978. The...
This circuit is indicated for the control of resistive loads. When S1 is opened, the triac turns on...
A VCO or voltage-controlled oscillator, which uses only two of the LM3900 amplifiers, is shown in the...