LED Tester

LED Tester

LED Tester
A handy LED and diode testing tool. Use it to easily determine LED polarity, forward voltage, and brightness at various test currents.

LED Tester provides a constant test current and reads out the diode forward voltage. Works with regular LEDs, bi-directional LEDs, Zener diodes, Schottky diodes, silicon diodes, etc. Battery powered with integrated battery, USB Micro charge connector.

Works with a variety of LEDs and diodes

Constant Current Test Settings

Three ways to test parts


Press the power button to toggle power on/off. After 5 minutes of inactivity the device will automatically power off.
The display will show dashes and the polarity indicators will flash when there's no LED or diode present.
Rotate the dial to select the desired test current.
Connect a test LED or diode to the breadboard sockets, SMT pads, or test leads.
The display will show the forward voltage. For bi-color LEDs (bi-directional diodes) the display will alternate.
The illuminated polarity LED indicates the anode (positive) lead of the LED or diode.

Testing SMT diode Testing 5mm Blue LED Testing 10mm Red LED

Testing SMT diode Testing 5mm Blue LED

Design Documents

Schematic Diagramschematic_j724_led_tester.pdf
3D Print Filesmechanical_j724_led_tester.zip
PCB Gerbersgerbers_j724_led_tester.zip
Source Codecode_j724_led_tester.zip


Power Requirement5V Micro USB connector, 650mA maximum
Dimensions103x103x45 mm (4x4x1.8 in)