Component Tester in a Keychain

Description

Component Tester in a keychain is a universal testing device for electronic components with three or lesser pins. It can automatically detect the plugged-in electronic component and measure the desired component parameters without having the user to manually select the component type, unlike the multimeter. It is based on the popular AVR TransistorTester.

It measures approximately 6cm x 3cm and is a one-button device that is capable of testing components such as resistors, capacitors with their ESR values (if any), inductors, diodes, transistors (BJTs, UJTs, and PUTs), FETs (JFETs and MOSFETs), Thyristors, TRIACs and more. Additionally, a function generator is available at Test Pin 2. To make it look a premium tester, I ordered the PCBs with a matte black soldermask from PCBWay, who also sponsored this build.

Details

Being an electronics engineer, I always wanted to have a portable component tester, which could test every electronic component out there. In 2016, I built myself a Component Tester based on AVR TransistorTester by Markus F. and Karl-Heinz Kübbeler. This summer, I thought, can it be made pocket-sized? Since my last version was quite big and difficult to carry around.

I started redesigning the PCB with SMD components and an OLED display since it is small, lightweight, and consumes less power. I wanted to retain banana jacks since they offer testing device a robust look and makes it more compatible. Say, I can use SMD tweezer probes for testing SMD components or say I can use alligator clips or anything else. I am no longer limited to plug in my part to the tester to test it.

After spending a few hours fiddling around the PCB layout, I managed to bring it down to as small as 58mm x 32mm (2.28in x 1.26in). Pretty little, right? To make it a fit as a keychain, I added a punch hole on the bottom right corner of the PCB so you can put in a keychain ring or a fancy lanyard. The tester boots up as soon as you power it up via USB C.

Once you connect the component, press the button next to the display to begin testing. Since it has only one button, it makes it easier to use and makes it look less complicated as an electronic tester, which may appear very complex to use at first to many users. Also, to navigate to menu the user just needs to double press the button once a component has been tested or a "No component screen is shown".

I used 0805package components for the tester since they are the smallest components one can solder by hand and can be eyes directly without a magnifying glass. I used solder paste along with a hot air reflow tool to solder in the components.

A HUGE THANKS TO PCBWAY FOR SPONSORING THIS BUILD

PCBWay offered to step in and helped me to support this project. They also offered their PCB services for the build. I got PCBs in premium matte finished soldermask which just upgrades the overall build quality of the tester. They offer 10 custom PCBs for as low as $5 with a wide array of choices such as soldermask colors, surface finishes and much more. The turnout time for PCBs was amazingly fast. I got my PCBs delivered in 3 days from the day I placed an order. They also examine each PCB design manually before manufacturing so you do not receive any defective PCBs. I recommend trying their PCB service if you need one.

Build instructions

Step 1

The first step in building the keychain component tester is getting the PCBs fabricated for it.

You can find the Gerber files for PCB manufacturing under files section or on project's GitHub repo.

I used PCBWay's Prototyping Service for getting my boards fabricated. They offer great quality boards for a very low and affordable price. They also offer a variety of solder mask options to try. I got my boards manufactured with Matte Black solder mask which makes the PCBs look very premium.

Alternatively, you can click the left image to order PCBs directly from PCBWAY. You can also add an SMD Stencil from them for just $10.

Step 2

The list of components in the components tab provide a detailed information on components you need to order to get started with the assembly process. The components have a manufacturer's reference number so you can hunt the parts hassle free.

I usually start by soldering resistors first followed by capacitors and then moving onto bigger components like microcontroller, buttons, OLED Display, etc. It makes life a bit easier.

⚠️ REMEMBER TO ALIGN MICROCONTROLLER'S DOT WITH DOT ON PCB (NEAR C6) BEFORE YOU BEGIN SOLDERING IT ⚠️

Step 3

Lightly tin the base of PCB where banana socket goes into and slide in the socket as shown. Once you slide in put  a bit of solder between the little space between hex nut and the base. This will ensure a string connection and give you better and more accurate testing results.

Step 4

1. Hardware Setup

Using a USBasp programmer connect it to the ICSP Header on the board.

Refer the following pinout for connections (Bottom Side of PCB)

2. Software Installation

⚠️ REQUIRED: You must have AVRDUDE installed in your system in order for following instructions to work.

In Terminal/Command Prompt, navigate to folder's location with above files and execute the following commands-

// Flashing .hex and .eep files to MCU

avrdude -c usbasp -B 20  -p m328p -P usb -U flash:w:./TransistorTester.hex:a -U eeprom:w:./TransistorTester.eep:a

// Setting fuses for MCU

avrdude -c usbasp -B 200  -p m328p -P usb  -U lfuse:w:0xe2:m -U hfuse:w:0xd9:m -U efuse:w:0xfc:m

Step 5

Power the tester 🔋 TAA DAA!! You just made yourself a keychain component tester 🤩

Plug in 🔌 the components you wanna test. Cheers 🥂

OR Get fully assembled tester on Tindie