Simple 5V regulator (CB8815E)

This simple 5.6 V regulator circuit was found in a 1966’s Philips. The zener can be changed to obtain other voltages.

Flood Alarm (CB12183E)
This circuit activates a relay when the water reaches the sensors. The circuit is from a magazine...
White Noise Generator (CB412E)
The noise comes from the PN junction of a common silicon diode. Since no gain is given by the...
Audio Preamplifier (CB16297E)
We have here an interesting audio preamplifier, which can be useful to those who are looking to...