I have an optek Photologic® Slotted Optical Switch. It is meant to turn off when the near infrared emissions (850 - 940nm) are blocked.

It has five wires as follows:

enter image description here

I am unsure about what to do with the anode and cathode, (most likely connect the anode to Vcc).

Firstly, I connected Vcc and GND but the signal voltage did not change when the LED was blocked.

Next I connected the anode to Vcc and the cathode to GND Aas shown below and retried.

enter image description here Still nothing.

Am I missing something obvious?

  • \$\begingroup\$ Not to Vcc directly but to Vcc through a biasing resistor to meet the "input diode" specifications. \$\endgroup\$
    – Eugene Sh.
    Commented Aug 11, 2016 at 15:08
  • \$\begingroup\$ You probably have blown the LED already with that connection; better try another device, this time with a several hundred ohm resistor between Anode and Vcc. \$\endgroup\$
    – BobU
    Commented Aug 11, 2016 at 15:17
  • \$\begingroup\$ @EugeneSh. BobU, thanks guys will give it another go, with another one \$\endgroup\$
    – SeanJ
    Commented Aug 11, 2016 at 15:33

1 Answer 1


The LED should be powered via the Anode and Cathode pins, the same way any other LED is powered - with a series resistor to limit the LED current to a safe value.


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