This is the receiver from the previous alarm system. The circuit is from Radio Electronics, April 1989, and has an LDR as the sensor. Optical devices should be used to improve performance.
This circuit can be used to measure the frequency of a low frequency square signal. The signal can be...
This circuit was published in an English magazine from 1977, but it can be easily assembled since...
We found this circuit in an old documentation. What it does is flash two LEDs when night falls or when...