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.
|Digikey Part Number|
|470 ohm resistor||470QBK-ND|
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.