For measurements between 30 and 40º C this circuit was found in the documentation of 1968. The sensor is a difficult component to obtain today.
Using in operational amplifier is possible to increase the dissipation power of a zener. This...
This circuit produces a whistle sound when acting on switch S1. Aids is applied to a transformer that is...
Found in an old Popular Electronics, this circuit has a gain of 20 dB. The integrated circuit is...