This is an extremely useful device that takes all the headaches out of figuring out how to wire your LEDs. If you are a newcomer to the LED world, it may be wise to start off with something like this. Simply insert it into your circuit and your 20mA LED will light up as it should.

Another great application is automotive use — there is a fluctuating voltage in an automobile and this device will ensure that your LED is operating properly at all times.

This simple device limits the current through itself to 20mA. When a voltage is applied (anywhere from 2 to 45V) it will actively adjust its own resistance to allow just 20mA (±3mA) to pass through. This makes it a perfect replacement for current-limiting resistors in LED circuits — you won’t have to calculate resistor values or worry about a varying voltage source.

The current limiter can be placed anywhere in the loop with LEDs, but needs to be placed with the proper orientation, or it and your LEDs could be damaged. The board has 0.032" solder holes which can accommodate wire down to 22AWG (tightly twisted) or standard 0.1" header pins. Note that at least ~2V across the current limiter is required for proper operation — below that and the current output will start to decrease. Multiple current limiters can also be placed in parallel to add current (40mA, 60mA, etc.).

Units are provided on a scored circuit board that can be broken apart using pliers and/or strong fingers.

Specifications

Size	0.334 x 0.100 x 0.077"
Hole Size	0.032"
Max Wire Size	24AWG (easier fit), 22AWG (must be twisted tightly)
Current	20mA (±3mA)
Voltage	2–45V (across the current limiter itself)
Heat Shrink Type	3/32" clear
Heat Shrink Length	0.5" per unit

Use Example

Suppose you have a vehicle and want to put 3 LEDs in using one of these drivers. The LEDs are 2 blue (3V each) and one red (2V). The vehicle’s electrical system has a minimum voltage of 12V. With this driver you just need to make sure you have enough voltage for everything:

2V (red) + 3V (blue) + 3V (blue) + 2V (driver) = 10V

Since 10V is less than the 12V supply, everything will work great.

The LEDs must be wired in series — when you wire LEDs in series the voltages add up, but the current requirement stays the same (20mA). If you are unfamiliar with how to wire in series, please take a look at one of the product images that depicts how to wire LEDs in series with the driver.