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.
The deviation of characteristics of this circuit normally referred to the temperature is very low....
Found in a 1969 Electronics World, this circuit generates low frequency signals with two...
Suggested by Texas Instruments in 1968 documentation, this circuit uses components from the era....