Recommended by 90s a Radio Electronics, this unit uses a transformer with a 70 V x 5 A secondary, being indicated for powering amplifiers from 50 to 100 W.
We found this circuit that uses a thermistor as a sensor from the 1991 Electronics Experimenter Handbook....
Found in an RF Design from the 90's this circuit is intended for crystals of less than 1 MHz....
This circuit was obtained from an English circuit manual. Components are common and LEDs can be 3...