This circuit was obtained in an American documentation from the 80's. The transistors can be equivalent to those indicated and the crystal can reach a few tens of megahertz.
This electronic variac has the traditional configuration with triac already explored on the site,...
With this oscillator we can obtain a signal of 10 W of power at the frequency of 100kHz. The...
This circuit is based on an LM3900 transconductance operational amplifier, found in 1992...