Suggested by a 90s EDN, this circuit supports almost any LED as a source and a phototransistor as a detector. The circuit operates with a PLL 567 at a frequency of around 40 kHz.
This circuit is from an old documentation of Radio Shack from the 70s. The transistor should...
When the power is cut off, this circuit keeps the flashlight on for a while, allowing it to be...
This circuit was obtained in an old Popular Electronics. It makes use of quite common components....