This Schmitt optical trigger with LDR was found in old documentation. The relay must be sensitive, or an additional step must be used to trigger it.
This frequency band below 15 kHz converter was found in a Popular Electronics from the 90's. The...
The circuit presented is a 10 MHz oscillator with crystal, which already has several splitters for...
We found this circuit in the November 1992 issue of Radio Electronics magazine. The circuit has...