Leds have a negative and a positive connection. In the picture below you can see this.

The long pin is always the positive connection and the short pin the negative.If you have an old led with cut off pins you can still find out which pin is what by looking for the flat side of the led. The pin nearest to the flat side of the led is the negative pin.

The normal voltage for the different colour leds are:

Red: 2,3 Volt

Yellowl/Orange: 2,3 Volt

Green 3,6 Volt

Blue 3,6 Volt

\white 3,6 volt

All are most common about 20ma.

If you want to connect a led to a power supply that gives more output in volts then needed you need to connect a resistor to the led.

You can order these resistor at this webshop. You only have to choose the wanted voltage and we will provide you with the right resistors for your leds. We always supply you with the save resistor version. You can find these resistors in the menu electronic components.

If you want to make another choice you can calculate the needed resistors in a different setup down here.

Use this calculator on your own risk. We are not responsible for any damage!

Led resistor Calculator

Power supply Volt [3-24 Volt] Led voltage (Uf ) Volt [1.6-4 Volt] Led milli amps - (If ) mA [2-70 mA (20 mA is standard] Leds in series piece(s) [Standard 1]   Calculated resistor Ohm To use E12 resistor 1) Ohm Colorcode resistor Power lost in LED 2) mW Power lost in resistor 2) mW The resistorvalue to use is  is based on the E12 series.  Power calculation is based on the E12 resistor values.