Found in a 1964 publication, this circuit makes use of transistors from the time. It operates on frequencies up to 3 kHz.
This circuit uses a transistor as a sensor and operates in the range of 0 to 50º C. We found it in...
This circuit was found in a Poptronics of the 90's. The components can be changed to the desired...
In the figure we have an interesting protection bridge against power polarity inversion of a...