Using an LDR, this Philips circuit directly activates a relay when light strikes the sensor. The relay is 45 V with 20k coil resistance. The 220 nF capacitor must be polyester for 400 V.
We found this circuit in the 2005 Linear Technology component manual. The circuit can be used as a...
This circuit was found in an 80's Electronic Design. The frequency depends on the crystal and the...
This circuit appears in other configurations on this site. Its purpose is to operate a small water...