The configuration shown was found in an old Poptronics but can be easily assembled using a common calculator photocell. The relay is according to the supply voltage.
November 2016 - Mouser Electronics already has Maxim's MAX17245 DC-DC step-down converters to...
This variable frequency oscillator with the 4093 was found in a Popular Electronics from the 90s....
This circuit was found in an old Philips publication. The circuit supplies a voltage corresponding to 4.5 V...