We found this circuit in a 1980s documentation. Equivalent components can be used. The circuit senses temperatures in the range of 0 to 50º C and uses a transistor as sensor.
This directed coupled amplifier uses a transformer to drive a low impedance loudspeaker. This...
This resistance meter uses a two-transistor oscillator as basic configuration. The tone produced...
We find in a Radio Electronics of the 90s this low noise amplifier that makes use of an uncommon...