These circuits were obtained in an Electronics Now from the 90s. The integrated circuits are from that time and the power can be between 1.5 and 2 V.
This circuit activates a relay when the water reaches the sensors. The circuit is from a magazine...
The noise comes from the PN junction of a common silicon diode. Since no gain is given by the...
We have here an interesting audio preamplifier, which can be useful to those who are looking to...