I wish to trigger a relay by exposing the sensor from a nightlight to an area on my computer monitor which I can change from black to white. The tiny board on the nightlight, containing the LED, has been removed and wires soldered to the connections at the light's larger board. To this point, everything works beautifully. Trouble is, the up voltage is only a little over 4 volts and it never drops below about 0.75 volts. I don't want to control the Hoover Dam generators, but I would like to control, say, a garage door opener, though it might take a chain of 3 or 4 relays to get there.