Electronic Component Tester (with a Nice Case)




About: Wile E. Coyote, passionate DIYer, wasn't as unlucky as you might think. If you try you will understand my statement: some of its contraption WERE ACTUALLY WORKING, at least at the beginning. It usually didn'...

Have you ever had a faulty and/or broken device and found yourself thinking "what can i recover from this (s)crap"? It happened to me several times, and while i was able to reclaim most part of the hardware i wasn't able to reclaim most part of the electronics components. The issue wasn't about desoldering them, but to identify them instead. Not to mention the even more important check of their working status.

There are numbers of different projects that are supposed to convert an arduino into a component tester and i'm sure that they can do what they are promising, but i guessed why should i spend time (and basically the same amount of money) to build the PCB and flash some software instead of buying a really cheap but reliable pcb, already populated and with the right software flashed. I can actually have more fun hacking a standard naked module into a fully functional device.

The main upgrade is to replace the 9V battery with a 18650 Li-Ion cell with its charge/discharge protection module. I want my tester to be rechargable and to be potentially powered by either usb port or whatever power supply that can provide 5V. There's more! Evenf if you compare the 18650 with a rechargable 9V battery the mod will be more flexibile because you don't have to open the case to charge it and, even more useful, you don't have to wait if the battery is depleted. Just plug in an usb cable or a 5V power supply and use the tester immediately. (a depleted 9V rechargable battery have to be put it under charge for a while)

Last mod is to have an additional testing port to allow some phisically big components to be tested. To do that i'll add a 3 pin dupont female connector on the side. You can attach everything you want to these pins, i simply use another dupont connector (male) with three test clips/probes.

Step 1: Components and Tools

The main module, called LCR-T4, can be found on Bangood and Amazon.

I suggest to purchase the module on Bangood since i can't guarantee that the Amazon seller will deliver the very same module, the picture and the description are ok but who knows...

The additional featurs requires a TP4056 module (Bangood, Amazon) and a step-up DC/DC converter (Bangood, Amazon).

Since you would follow this instructable only if you want to reclaim electronic components i won't spend time to tell you that you'll need a soldering iron, wires, etc...

You should be able to reclaim 18650 cell from whatever laptop battery you have at hand but, in case you don't have any or don't want to bother with li ion reclaiming, you can purchase one cell from Bangood or Amazon. You "shouldn't" purchase these too-cheap-to-be-good cells for other projects because they won't match their specs for sure, but on the other hand this project's power requirement is so tiny that it doesn't really matter.

If you want to have all the addiditional features you should buy also a two pin connector, a three pin dupont connector and some hook test clip probes.

Hint: the three pin dupont could be a spare servo (RC servo) cable.

Step 2: Print the Case

Now follow this link and download the files. The printing instructions are on the Thingiverse page but it actually is a really easy-to-print case, you shouldn't need any instructions.

Pla, abs, whatever filament will do the trick.

Step 3: Electrical Wiring

As you can see the eletrical drawing is quite simple, you have to perform these few connections:

  1. connect the TP4056 output pads with the step-up input pads with a couple of wires
  2. connect the TP4056 input pads with the 2 pin recharge connector
  3. connect the TP4056 battery pads to the 18650 cell
  4. remove the 9V original connector
  5. connect the step-up output to the module input
  6. connect the 3 pin dupont connector with the first 3 pin of the blue spring socket.

By "connect" i obviously mean "solder" a cable. Be really careful with the soldering on the li-ion cell, it's dangerous! There are plenty of suggestions and tutorial about this step online, just search "18650 soldering". Be sure to have understood how to do that in a safe way (basically: be as quick as possibile because the heat of the soldering iron will damage the cell).

The battery cables have their paths/holes in the bottom part of the case, please use them.

The step-up module have to be set to output 9V as soon as possible and you can do that turning its trimmer with a simple screwdriver. You have to do that mandatory before the 5th step and you can easily do that once you've performed the 3rd step, just don't forget it!

Once soldered everything you should check with a multimeter the effectiveness of every connection and check id every pad isn't shorted with another one.

If everything is ok press the tester only button to see if it powers up and it works properly.

Step 4: Finalize the Case

Now all the components (also the 18650 cell!) can be attached to the case with few drops of hot glue. I suggest to use few drops of glue also on the soldered connections, to prevent mechanical stress. You can/should also use some glue to attach the 3 pin dupont connector on the frame. I've added a zip tie on the 2 pin recharge connector, as usual to avoid every chance of mechanical stress when i plug and uplug it.

You can/should add a small sponge cube or whatever soft material to be sure the 18650 will remain in place in case the hot glue will fail over time (it's the only heavy components, therefore the most exposed to mechanical stress).

Once the glue is cold you can carefully close the case with 4x M3x25 screw. The nuts have their slot in the bottom of the case but they aren't mandatory (the screws can tap the holes).

It's done, now you have your li-ion powered component tester, happy days!

Step 5: Usage

I've learned from the comments that i should add more info about how to use this tester. The testing operation is actually quite easy, you only have to connect the component that you want to identify and then press the only button. If the tester can identify the component it will show the component's device class and its main specs, otherwise it will say that it can't identify the component or that the component is damaged. This could happen, for instance, if you connect a 7805 linear regulator, it's not damaged but it can't be identified. In other words you can't determine if an unkown TO-220 item is a faulty mosfet or a functioning linear regulator.

You can connect the item to be tested in three way:

  1. by the cyan spring connector (ZIF socket): put the item's legs in the holes and push the small lever down
  2. by the smd pads: place the item on the exposed pads in the central funnel
  3. by the external probes connector (if you added the 3 pin dupont connector)

The external probes connector can work with whichever probes you want, as long as they can be wired to a dupont male connector. I've used three small hook probes and another servo cable but you could use alligators clip and any three wire cable., it doesn't matter

ps: the zif socket is a 7x2 socket and as i mention before the three "logical" input have multiple phisical connections. The pin numbers are:

123 - 1111

222 - 3333

That's all, happy component tester, folks!
ps: if you find this -ible interesting or it helped you please consider a little paypal donation, it will be appreciated.

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10 Discussions


I bought a couple of these off the internet recently and it's an extremely useful piece of equipment for sorting and testing components. It's expecially useful for identifying FET's, Mosfets and Bipolars

1 reply
garzoFranks Instructables

Reply 6 months ago

It is! I've finally sorted a full tray of reclaimed yet undefined components. The best part is that since they are "free" components i won't mind to use them "electroboom style". :D


Reply 6 months ago

Because the TP4056 output is the 18650 cell voltage and it's significantly lower than the standard input tension of the tester module, it can reach 3V . I've tried to gradually reduce the voltage with my variabile power supply and the module "could" work at 6V but the LCD contrast is quite low and i can't guarantee that identification script will work as it was supposed to do.


Reply 6 months ago

but you have 7805 vr, behind 9v conection. I removed it, and conneced output from charging module directly to where otput of 7805 was. works well, just background light is off. who cares, im not working with electronics in dark.


Reply 6 months ago

While a lcd backlight is comfortable i agree that's not mandatory.
The issue that i'm really uncertain of is how the tester will perform with a modified power supply. Even though the microcontroller might "work" at 3V3, are you sure that he can handle also a discharging 18650? With the TP4056 we are talking about 2.5V limit.
Even if it doesn't reset or power off are the analog readings accurate and reliable?
If the Vcc is not 5V as expected it could provide wrong measures with the ADC, therefore you really should have a stable and regulated 5V Vcc. In order to have this 5V regulated reference voltage you need a 7805. As per the 7805 data sheet, whichever package and/or version, you have a rated minimum input voltage of 7V. https://www.sparkfun.com/datasheets/Components/LM7...
The only option i can see to remove the step-up is to use two 18650, but you have to find a 2 cell alternative for the TP4056, and you can't use the full cells capacity because under 3.5V per cell is the rated limit for the 7805. Can it work with less that 7V? Maybe, but maybe it depends on the specific specimen and that's not true for everyone.
IMHO you should follow the instructable as it is since your objection is not correct under every aspect.


6 months ago

What components are you able to test with this?

1 reply

Reply 6 months ago

From the producer's page: This tester can identify NPN and PNP transistors, N-channel and P-channel MOSFETs, diodes (including dual diodes), thyristors, triodes, resistors, and capacitors. I've tried it with transistors, mosfets (N and P), dual diodes and capacitors so far, but i'm confident that it will work with all the listed components.


6 months ago

I wished you've shown how it works and can identify the component and what each pin is. I have a part with a part number that I can't find any data on. It looks like a standard TO-220 power device, but I don't know if it is a power transistor, a power MOSFET, a voltage regulator, or some custom device, since the part number seems to be something the manufacture labeled. And the manufacture is no longer in business and the unit it goes in, is well over 30 years old. And for that reason, I don't know how to test it to see if it works. Connecting it up wrong is now the answer.

1 reply

Reply 6 months ago

I probably should add more info about how it works, but in the end it's really easy to use. You have several holes in the cyan spring connector but actually only three at time are important, the other ones are just other "copy" of the same pin. The first top-left three, for example, are connected to "probes" nr 1, 2 and 3. You only have to place a component with its legs in these slot, block it with the lever and press the button. The tester will analyze it and it will show on the screen the component type and the main specs. That's all. You don't have to use a specific pin for -just an example- the gate pin of a mosfet, you just randomly put its legs in the spring connector and push the only button. This tester can identify NPN and PNP transistors, N-channel and P-channel MOSFETs, diodes (including dual diodes), thyristors, triodes, resistors, and capacitors. If your component is something else it won't tell you anything but "faulty part".