Found in a Westinghouse Silicon Power Handbook from the 60s, this circuit makes use of period components. Special high voltage transistors are used. Zeners are 15 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...