Found in an American publication from 1968, this circuit can be made based on a TIP42 that must be mounted on a heat sink. The transformer is 25 V with a current of 3 to 4 A.
This sensor uses a capacitive system that oscillates at 45 MHz with the empty glass tube. Its...
We found this CMOS circuit based on the PLL4046 in the December 1989 issue of Radio Electronics magazine....
This 1967 Electronics World circuit is suitable for frequencies up to 1 MHz. The setting applies...