The sensor is a photocell which is mounted in the tube at the opposite end from the lens. When light is aimed more or less directly at the lens, the beam is focused on the photocell the electrical resistance of which then falls dramatically. This change in resitance is used in a sensitive electronic circuit to activate (pick up) an output relay when the light level is high.
When light is removed, the cell will return to its high-resistance state and the relay will then drop out. When the cell is dark, it will typically have a resistance of 10 megohms. When the light level rises to 2-foot candles, the resistance will drop to about 50K ohms.
Shown in photo in conjunction with Photoelectric Relay Wabash #GS 401 (not included).
Dimensions are θ2.5x12cm.
Forensics Lab Supply Number 3178550.
Formerly Grau-Hall Corporation dba Grau-Hall Scientific.
Purchase orders may be sent by email to staff @ grauhall.com or by FAX to 916 379 9639 or by mail to P. O. Box 279592, Sacramento, CA 95827-9592.
All products shipped from Wabash, Indiana.