Review on High Quality Twidec Rocker Lighted Toggle Switch - 3pcs Set, 12V/20A, Heavy Duty, Green LED Illuminated - Ideal for Racing Cars, Automative & Auto Applications by Brian Tompkins

Many users have said this is a good switch and I agree. However, it is large, which is to be expected for a 20A switch. The front panel measures 2.7cm x 1.6cm (17/16" x 3/8"); the depth is 2.85 cm (9/8") and the switch protrudes an additional 3.2 cm (5/4"). So make sure you have a place to install it. It also has a heavy travel that requires some effort to move the switch. The seller provides a rudimentary switch wiring guide but does not have an internal diagram. I designed the circuit shown as a blue outline in my drawing. I tested the versions with green and blue LEDs. They, and probably all versions, use a white LED with a color filter built into the toggle switch. The switch is listed as a 12V part, but you can use it with other DC voltages. For example, the LED works up to 5V DC. The ground connection (marked OFF on one side of the switch) is for the LED only. You don't need to connect it unless you're using an LED. And you SHOULD NOT connect it when switching AC voltage as this will most likely destroy the LED. With 12V applied, the LED will draw 9.5mA and may be too bright for you. You can lower the brightness by adding a resistor in series with the ground pin. For example, adding an extra 1kΩ resistor worked fine for me at 12V. If you're using DC voltages above 12V, I highly recommend adding an external resistor so you don't burn out the LED. only when the switch is flipped. If you want the LED to be on all the time, use a wire marked 20A as the switch input. The output of the switch in this case is the terminal marked 12V (+ on the opposite side). If you want the LED to only light up when the switch is pressed, use the pin labeled 12V as the input for the switch and the output of the switch will then be the pin labeled 20A. Another thing that Things to note is if you are using the switch to power an inductive load such as a DC motor or servo, then flipping the switch can result in a large inductive voltage spike of the opposite polarity and the LED may be destroyed. This may be at the root of the issue noted by some reviewers where the LED worked at first and then stopped working. The solution is to add an external diode connected as shown in my picture. This limits the voltage and protects the LED. A good candidate for this diode is something like the 1N5818, a fast-switching Schottky diode that can handle 40V DC and up to 25A surge current, available from Revain. However, other common diodes such as 1N4004 or 1N4148 can work even though they have a slower switching speed or lower surge current rating.