Found in a 1990s US publication, this alarm circuit detects when a light beam is interrupted. Optical resources may be used for the sensor and instead of the alarm a relay may be used.
In this circuit we have the voltage multiplied by 5, obtaining between 50 and 80 V output when the...
We found this circuit in a 1962 publication by General Electric. The circuit applies to common...
This timer for a few minutes was originally indicated for photographic applications. We found it...