This dual flasher for high brightness LEDs was found in an American documentation from the 90's. The circuit can be powered by lower voltages with the reduction of R1 and R4.
We found this heart rate sensor circuit in a Popular Electronics from the 90s. The placement of...
This circuit, found in an old magazine of the year 1968, uses a Power germanium transistor. This...
This project came out in an article of mine (Newton C. Braga) in the Popular Electronics magazine of...