Kevin Rye designed a simple LED tester:
I decide to put together a small LED Tester board. It’ll be powered by a small coin cell battery. I can pick up an LED with a pair of tweezers and just simply tap it to the solder pads. If it lights up, I know I’m holding it the right way, or not. As far as a PCB, I want it to be super simple and super cheap. I really don’t want to spend $10 bucks on something so simple. However, I don’t want it to be a one-trick pony either. Ideally, it should work for through-hole LEDs as well, as 1206s and whatever other sizes I can’t think of right now. Do SMD LEDs come in an 0805 package? I’ve never seen one, but it’s probably a good idea to place some large pads on it so that it’ll work for anything.
Kevin’s LED tester - [Link]
Hemal Chevli blogged about his transistor tester project:
It has mega-8 as the brain, lcd to show specs of the transistor like which pin is which, what type of transistor it is eg NPN,PNP, N-MOSFET,P-MOSFET, etc., many components can be tested like different types of transistor, diodes, resistors etc, the good thing about this is that it also shows which leg is which, no need to open the data sheet
Transistor tester project - [Link]
LEDger Led (polarity) tester:
Everytime I solder a SMD LED on a pcb I have to turn on one of my multimeters and flip it over to diode-test mode and then probe the SMD LED to see which connector is the anode and which is the cathode. The LEDger is a small PCB with a button cell battery and smd footprints that allows me to, while still holding the LED in my tweezers. just hold it onto one of the footprints and see if it lights up or not.
LEDger Led (polarity) tester - [Link]
Gadget Gangster @ instructables.com writes:
A little bigger than a postage stamp, the Simple Servo Tester lets you control two digital or analog servos without using a transmitter or receiver, just plug in your battery pack to start testing.
Use it to check your servos before installing them into your models or to center your servos when setting up linkages. The Simple Servo Tester can also be tuned to precisely center your servos – Some manufactures consider 1.520 milliseconds to be center while others use 1.500 milliseconds.
Simple Servo Tester - [Link]
Trandi made this simple DIY Servo tester based on ATTiny85:
I had to test a RC speed controller that I wanted to use to control an electric car window motor, and for the 100th time I was facing the same dilemma: find 8 batteries for my remote control, dismount the RX part from the quadcopter and use that, OR grab the Arduino and write quickly some code to generate the corresponding signals? Neither of which was actually particularly handy… So I finally decided to build a small stand alone servo tester.
DIY servo tester based on ATTiny85 - [Link]
Raju Baddi writes:
A specialized test gadget that tests continuity quantitatively in both AC and DC modes could prove to be an indispensible bench test instrument. This article describes such a continuity test set up, which provides two different display options.
The meter (see Figure 1) can be used in AC mode to test/estimate capacitors, inductors, transformers etc. that are sensitive to AC current, while the LEDs can be used in AC/DC mode to test diodes, transistors, transformers, etc.
Method tests continuity in AC and DC - [Link]
Zener diode is a special diode, unlike normal diodes zener diodes are intended to work in the breakdown voltage. These components maintain constant voltage at its terminals. This is a circuit to help you find out what’s the breakdown voltage of your diodes.
- Read Vz value of zener diode in Led display
- Zener diode tester range: 1V to 50V
- Two scales 5mA and 15mA test
Zener diode tester 1V to 50V - [Link]
This is a very simple capacity tester. It consists of single resistor that discharges battery. Arduino measures the voltage drop across resistor. According to Ohm’s Law current = voltage/resistance. Every second value of current is divided by 3600 and summed up to get the capacity expressed in Ah (Amp per hour).
I have used two parallel connected resistors that total resistance is 6.9 ohm. Make sure that they have proper power rating, if you don’t want them to convert to smoke. If voltage across 6.9 ohm resistor is 3.7 V, then current – 0.54 A, power ~ 2W.
Arduino Lithium-ion battery capacity tester/discharge monitor - [Link]
Test Thyristor and Triac using this circuit. Pay attention on mains voltage!
Thyristor – Triac Tester - [Link]
AS with many tinkerers and junk electronics collectors, a variety of “acquired” power supplies wind up on the author’s shelves to await attention. But are they worth keeping? Testing them with a resistive load is messy and difficult, and with high current supplies it is nearly impossible, unless you have a carbon pile! The tester whose circuit diagram is shown in Fig controls supply currents to 20A, and voltages from 1·7V to over 50V. Current control is so stable that once the current is set, a supply voltage can be varied across this range and the current will remain constant. Maximum power will depend upon how well the pass transistors utilize heatsinks.
Power Supply Tester circuit - [Link]