Component Tester - Test Almost Anything !!





Introduction: Component Tester - Test Almost Anything !!

Arduino All The Things! Contest

Runner Up in the
Arduino All The Things! Contest

Being an Electronics student or hobbyist, you may have thought of getting a tester that could test almost anything "THE ELECTRONICS COMPONENTS, OBVIOUSLY!!"

Now what if I tell you that you can have one and that too made by yourself under INR 600 only (USD 10).

Coming upon COMPONENT TESTER so it can test almost everything, obviously not the power components because they require more current and power which our AVR Microcontroller couldn't handle !! Oh yeah, I forgot to tell you guys that we would be using an ATMEGA328 for our build !!

Yes, the same microcontroller which an arduino uno uses...!!

So, here's what our Component Tester can test -

1. Resistors

2. Capacitors along with their Equivalent Circuit Resistance Value (ESR)

3. Inductors

4. BJTs

5. FETs

  • JFETs

6. Thyristors

  • SCRs
  • DIACs
  • TRIACs

7. IGBTs

8. Diodes

no the list doesn't end here.... it can test Voltage upto 50V, it has a FREQUENCY COUNTER and a FREQUENCY GENERATOR TOO :D

you can also detect the IR Codes by simply putting a TSOP Sensor on its test pins.... isn't that great :D

and yeah one thing i forgot to tell you guys it doesn't only detect the components it displays their respective values and properties too !!

No, don't thank me for such wonderful thing thank MARKUS F. the maker and developer of Component Tester and Karl-Heinz who developed the firmware for it.

Let's Start the build and you'll explore much more on the way to build your own..!!

Step 1: Order Stuff for Build !!

with some basic components and tools you will be ready to build...!!

Electronic Components

  • 1x 1nF (102) Ceramic Capacitor
  • 1x 10nF (103) Ceramic Capacitor
  • 4x 100nF (104) Ceramic Capacitor
  • 2x 22pF (22) Ceramic Capacitor
  • 2x 2.2uF, 50V Electrolytic Capacitor
  • 2x 1N5819 or any other Schottky Diode with current rating of 1A
  • 1x 7805 - 5V Voltage Regulator
  • 1x LM336 - 2.5V Voltage Reference Diode
  • 1x 10uH Inductor
  • 1x BC547 Transistor
  • 1x BC328-40 Transistor
  • 3x 680 ohm Resistor with 0.1% Tolerance (1% Tolerance would also do)
  • 3x 470k ohm Resistor with 0.1% Tolerance (1% Tolerance would also do)

NOTE: For 1% Tolerance and 5% Tolerance(not recommended but works with less accuracy) 680 ohm and 470k ohm resistors you need to make some changes in code and try to have all resistors indicating same value on multimeter.

UPDATE: For those who are having problems in finding 0.1% or 1% tolerances. You can use 5% tolerances. Just buy 5-7 resistors of 5% tolerances and find out 3 resistors having same value on the multimeter. I made another one for you guys with 5% tolerance resistors and changes the value of resistors in code and that worked too :)

  • 2x 3k3 ohm resistor
  • 2x 27k ohm resistor
  • 1x 100k ohm resistor
  • 1x 33k ohm resistor
  • 6x 10k ohm resistor
  • 1x 470 ohm resistor
  • 1x 15k ohm resistor
  • 1x 2k2 ohm resistor
  • 1x 200k ohm resistor
  • 2x 1k ohm resistor
  • 2x 10k ohm preset (Variable Resistance)
  • 1x 8MHz Crystal Oscillator
  • 1x ATMEGA 328/328p with Socket
  • 1x Rotary Encoder w/ Button Module and KNOB
  • 1x Red LED (you can use any colour I chose Red as it it used to denote POWER)

Hardware Parts

  • 1x 16 Pin Polarized Header Cable - Relimate Connectors
  • 3x 3 Pin Polarized Header Cable - Relimate Connectors
  • 2x 4 Pin Polarized Header Cable - Relimate Connectors
  • 1x 9V Battery Connector
  • 6x Banana Jack Connectors (Female)
  • 3x Banana Jack Connector Cable (with Male Heads)
  • 1x Enclosure Case (I used a plastic Switch Board Enclosure Case/ Plastic Project Box)

Tools Required

  • Soldering Iron
  • Some Solder
  • A Single Layer PCB (because I home etched mine for this as it reduces unwanted signals and noises in the circuit and being it a testing circuit etching your own PCB is advised for getting accurate results)
  • Solder Mask (optional)
  • Some strong cutters (to make cutouts on you enclosure)
  • Screwdrivers and Pliers
  • and some ISO-PROPYL Alcohol or Acetone would work fine to clean the flux residue on PCB (It its necessary that you clean the flux or it may cause some unwanted errors in your Component Tester).

Let's Start the build !!

Step 2: Schematics and PCB Build !!

This is a self designed and home etched PCB...!!

I used eagle software freeware version for designing PCB. I have attached the PCB (un-mirrored) files below so you can download and etch them at home. For etching you can refer to other instructables on how to go about etching process using Ferric Chloride(FeCl3).

You can Follow GreatScott's series on how to etch PCB's using Ferric Chloride-



UPDATE : I've uploaded Eagle Files :)

Step 3: Applying the Solder-Mask Onto PCB (OPTIONAL)

If you wish to apply solder mask u can follow the below video on how to go about applying solder mask.

I have attached the pad mask so to resist application of solder mask on component pads.

Step 4: Drilling Holes on PCB

For drilling holes on PCB you can either use a hand drill or a electric drill / drill press.

Step 5: Soldering Components on PCB

Be careful while soldering the 680 ohms and 470 kilo-ohms resistor which are test resistors !!

  • Do not apply more solder on these resistors as that can induce some unwanted capacitance or resistance in the circuit.
  • Do not leave flux on the PCB after soldering components !! This may result in some unwanted values u see on display. You can use Isopropyl Alcohol and some Cotton Buds to clean the flux on PCB.

Step 6: Preparing the Enclosure...!!

I used a plastic project box as enclosure for my COMPONENT TESTER...!!

I drilled holes for binding posts and DC jack socket then used a hot knife to make cutout for 16x2 LCD.

NOTE : desolder the grounded leg of push-button on rotary encoder module and connect that to positive side of LED along with wires coming from the PCB


  • PIN1 - LED Negative
  • PIN2 - LED Positive
  • PIN4 - +5V

Connect 2nd Pin of switch to LED Positive

Step 7: Uploading the Code to AVR

The code files are attached below as .zip file format so that you can compile an build code after making the necessary changes in configuration files.

Now open up config.h and make the following changes -

  • navigate to measurement settings and offsets
    • now in this section scroll to R_LOW and set the value of 680 ohm resistance you are getting on you multimeter try and choose 3 680 ohm resistance with same values showing on multimeter
    • now change the value of R_HIGH i.e. the value of the 470k ohm resistances you are getting on your multimeter be as precise as possible and try and choose 470k ohm resistances with closest values or same values showing up on multimeter.
    • change RH_OFFSET if you want or leave it as it is. RH Offset is Offset for systematic error of resistor measurement with Rh (470k)
    • change R_ZERO - Resistance of probe leads (in 0.01 Ohms).
      • Resistance of two probe leads in series. (Assuming all probe leads got same/similar resistance)
    • change CAP_WIRES - Capacitance of the wires between PCB and terminals (in pF).
      • 2pF for wires 10cm long
    • change CAP_PROBELEADS - Capacitance of the probe leads connected to the tester (in pF).
      • 3pF for about 10cm long probe leads
      • 9pF for about 30cm long probe leads
      • 15pF for about 50cm long probe leads
    • you can go through rest of values and play-around if you are familiar with AVR and coding. If not please do not alter anything else.

If you are facing problems opening .zip files I am sharing the Dropbox link to code -


UPDATE: If you are using usbasp programmer then you need not edit the Makefile else you need to goto line 54 and change

programmer = usbasp to programmer = <your programmer's name>

  • open command window in that folder where you have your code by holding shift and right click you will see an option of Open Command Window Here click that
  • type in make all
  • connect the Programmer with the ISP Header of Atmega328
  • type in make upload
  • then type make fuses
  • following to this type make clean

NOTE : I assume that you have avrdude pre-installed in your systems. if not youhave to download avrdude and install it before doing above steps.

Step 8: Assembling Everything As One Device

Before assembling just run everything and test one or two components so as to confirm everything is working fine.


So you made one component tester for yourself.... you can keep that handy on you workbench and use it to test your components more often...

UPDATE : You can see the menu for the tester which includes PWN Generation, Square Wave Generation, Frequency Counter, IR Code Detector, Calibration and Adjustment Menu by turning the rotary encoder left after turning the tester on.

15 People Made This Project!


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We have a be nice policy.
Please be positive and constructive.



Can this circuit be supplied with 3.7 Liion 18650 battery? How?


Please i need help to connect the encoder, i have tried in different ways and I
have not been able to

Sorry for the stupid question, I'm quite new to this. But what kind of encoder are you using? There's loads of rotary encoders, but are you using a specific model? If so, can you please tell me what model?

Thanks a lot! Great project by the way!

sera que esse projeto funcionaria em um atmega168pa(smd) devo copilar o codigo,eu uso o avrdudes com usbasp ,sou iniciante em avr

the instructions you have given showing that the one terminal of the start button is connected to +ve of led [2.23v] and the other terminal is connected to PD7 with 27k pullup resistor, which I have failed to understand.

Can you please explain the logic level and operations of PD7. As per circuit: PD6 is for keeping the system on [after release start button] & auto power off. PD7 is for checking the start button state [how and why please explain this if possible]

below the circuit i have made. now it is continuously probing. any help.


Thanks for sharing such a nice project.

can someone please give me the hex file at

hex file is available in the dropbox link

Wait, can this component tester really test capacitors? You are not showing any being tested in your photos! I need to test 350vdc 25uf caps...

yea it can test capacitors too I'll upload pics for capacitors too :)