Introduction: Simple Component and Continuity Tester

Make a simple component and continuity tester. This is used to test circuits and electronic components to see if they work.

Step 1: What You Will Need

What you will need

1 x 3 by 8 holes strip board
1 x 390ohm resistor
1 x LED (any colour)
Soldering Iron (with solder of course)
2 x Crocodile/Aligator clips
1 x PP3 Battery Connecter (I took my from an old PP3 battery)
Coloured wire eg. green&red;/blue&red; etc.
3-5 mm drill bit to break copper in the board

Step 2: Building the Circuit

Start by breaking the copper as I have done in the picture. Then place and solder the positive wires with the battery clip and the crocodile/alligator clips on the strip with the broken tracks as I have done. Then start by placing the 390ohm resistor leaving a break in the copper between the two leads on the broken track (next to the battery clip) and solder it in. Then place the LED on the broken track (the positive way around and next to the crocodile clip) and solder it in leaving a break in the copper between the two leads.

Step 3: Connect It Up

All thats left to do now is connect it up to a 9v PP3 battery and connect the clips to a component or circuit you are going to test. If you are testing an LED both LEDs will light up brightly. *Note if you are testing a capacitor remember to connect it with the correct polarity or you risk your capacitors life.

Resistors
LED bright for low resistance, less than about 1k.
LED dim for medium resistance, a few k.
LED off for high resistance, more than about 10k.

Diodes
LED bright with red lead to anode and black lead to cathode (stripe).
LED off with black lead to anode and red lead to cathode (stripe).

Zener Diodes
LED bright with red lead to anode and black lead to cathode (stripe).
LED dim with black lead to anode and red lead to cathode (stripe) if the zener diode voltage is less than about 7V.
LED off with black lead to anode and red lead to cathode (stripe) if the zener diode voltage is greater than about 7V

Transistors
For each pair of transistor leads connect the tester leads first one way, then the other way.
These are the results for an NPN transistor in good condition:
CE pair: LED off both ways.
BC pair: LED bright with red lead on B, LED off the other way.
BE pair: LED bright with red lead on B, LED off the other way.

These are the results for a PNP transistor in good condition:
CE pair: LED off both ways.
BC pair: LED bright with black lead on B, LED off the other way.
BE pair: LED bright with black lead on B, LED off the other way.

Comments

author
ВикторК made it! (author)2015-03-05

I made it :-)

simple-continuity-tester.jpg
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DavidRobertson made it! (author)2007-11-06
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MROHM made it! (author)MROHM2013-05-28

Yes!! That's Where It came From!!!

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lonenome made it! (author)2012-05-07

I had a fun time with this i actually made my own battery case for a 9v battery with a push button. I made the circuit on the back and used hot glue to hold it in place. Works good i had fun for about a hour testing random things around my house. This was my first project i actually got to work and i am sure it will get lots of use as i need to test my parts thanks.

author
cloner made it! (author)2007-10-24

can u please put a variation of this project using 110v or 220v AC? thanks :)

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matt byrne made it! (author)matt byrne2009-08-27

How about a using regular household light bulb ?

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TheMadTinker made it! (author)TheMadTinker2008-04-08

That would be an incredibly bad idea. For one thing, AC can kill you, and although it might encourage natural selection, I wouldn't want amateurs frying themselves or their components playing around with AC. There are some things that oughtn't to use mains power, and this is one of them.

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godfreyandthandi made it! (author)godfreyandthandi2009-08-22

+1 its just stupid if you don't know what you are doing.

author
computerwiz_222 made it! (author)computerwiz_2222008-04-17

I completely agree with you on this one. Also, why would you want an AC polarity meter when AC is non-polarized. Just a little tidbit of information: If you use an LED on an AC circuit, it will work, but it will be reversing the polarity of electricity at 60 Hz. This means that the LED will only be on for half of the time it is running. This is called the duty cycle, and in this case the LED would only be running a 50 percent duty cycle.

author
KrakenFan69 made it! (author)KrakenFan692008-11-16

Actually AC is polarized. It does matter to ensure a safe installation. Will a light still come on if polarity is reversed? Sure but now you have energized the screwshell of the lamp and the neutral is in the bottom pin. If you try to remove the bulb and touch the shell (and are grounded you can get shocked. This site does a good job of explaining it simply.
http://www.bainb.co.uk/polarity.htm
End of the day, this is not a good project to use AC on.

author

Yeh, AC + this Project = Bad Idea

author
comodore made it! (author)2009-02-17
# Not bad a nice project!
  • Not bad a nice project!
& Not bad a nice project!
@ Not bad a nice project!
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gamer made it! (author)2007-10-23

good!!! someone finally uses a resistor. thank god. by the way, very good choice of resistor, is protects (any colour) of l.e.d.s.

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computerwiz_222 made it! (author)computerwiz_2222008-04-17

Actually, 390 ohms is only for a certain type LED. When calculating the resistor, you take into account source voltage, diode forward voltage and current. Every LED is slightly different, but from experience, 560 ohms is generally good for a source voltage of 12 volts.

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imarzouka made it! (author)imarzouka2008-08-23

ya.. you can use this calculator (http://ledcalculator.net) to do the job for you

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jack_savage made it! (author)2007-10-23

it is a bit of an overkill but i still think that its a nice idea

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Handsome-Ryan made it! (author)2007-10-23

neat idea for those times when you don't want to bust out the multimeter to troubleshoot a bad solder joint.

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inspector_fegter made it! (author)2007-10-23

Very nice! I can use this in a variety of applications. Maybe you could figure out some sort of housing for it as well to make it less fragile and more heavy duty for daily tasks. Just a thought. :)

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