This circuit was found in the 1992 Radio Electronics Handbook. It is used to test VCR recording heads. It can also be used for other purposes.
This amplifier for automotive use was found in the SGS manual of linear integrated circuits of...
This circuit was found in documentation from the 70s. We can try current JFET transistors....
This circuit makes use of a thermometric sensor that heats or cools according to a current of air....