Bi-color LED indication on Logic Outputs of P4800, DFR22, SLX4L, SCM820, SCM810, SCM410

Date Updated: February 22, 2018 FAQ #2938
Instead of using a simple single color LED to indicate the status of the logic output on the P4800, I want to use a bi-color LED that switches between red and green. A bi-color LED is easier to see in bright lights than just an LED that goes on and off. How can I connect a bi-color LED to the logic outputs?

The following diagrams show how the circuit is made for a bi-color LED. This can be used with any Shure product that has Logic Outputs on it.


The 7400N chip actually has 4 NAND circuits in it. Thus, only one 7400N is necessary for 4 LED's. Likewise, the 7404N has 6 inverters in it and only one 7404N is needed per 3 LED's.

When wiring the bi-color LED in place, if the colors are opposite of what you were expecting, simply swap the leads of the LED.

Parts Information

Digikey Part Number





470 ohm resistor


All electronic components needed for this project can be ordered from Digikey (1-800-DIGI-KEY). Many different bi-color LED's are available with various sizes, mounting, and colors. Notice that this circuit uses a two conductor bi-color LED, not a three conductor bi-color LED. When you are looking at purchasing the bi-color LED, make certain it only has two leads coming off of it. Digikey offers a good selection of bi-color LED's.
NKK Switches manufacturers switches that have bi-color LED's built in. Thus, when using the control inputs and logic outputs of the P4800 together, you can have a switch that lights up two different colors depending on the state. Digikey sells NKK switches.