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.
We found this circuit in an old documentation. The operational can be of any type and the...
Found in an 1868 Mullard documentation this circuit has a dynamic range of 10 Hz to 25,000 Hz....
Found in a Popular Electronics from the 90's, this circuit converts a 40 V symmetrical source to a 5...