This circuit was found in the December 1992 Radio Electronis magazine. R2 is an NTC, there is a MOV protector or NTC thermistor. The current depends on the thermistor used.
This crystal configuration can be made with triggers of any logic. The frequency is given by the...
This circuit was obtained from an 80s factory manual. The integrated circuits used are uncommon...
We found this circuit in an old American documentation. It is an electronic rheostat with a...