The purpose of this circuit is to test NPN and PNP transistors and to identify their pin layouts, ie ECB, EBC. I find myself testing a lot of transistors to determine their pin layout and type and as such find that building the test circuit on a breadboard has become a hassle so I wanted an easy circuit that would be more permanent and would allow me to test transistors.The transistor type NPN/PNP determines the polarity of the connections. The orientation of the transistor is the pin layout. I define the pin layout when looking at the top of the transistor with the flat side facing toward you. That is probably not the official way to classify them but it makes more sense to me when I am placing them in a circuit.- EBC stands for Emitter Base Collector. When I use this acronym I am saying that the pin to the left is the emitter, the middle pin is the base, and the right pin is the collector.- ECB similar to the above acronym stands for Emitter Collector Base. The emitter pin is again on the left but the middle pin is the collector and the right pin is the base.I have gone through about 100 transistors that were pulled from old electronics and have never found any other orientations so i have found that there is no need to test for anything but these two orientations.

This circuit requires few parts and it should be easy to obtain many of the required parts from your own supplies or pick them up locally. I had all the parts on hand that were leftover from previous projects or where recovered from old electronics. If you need to buy these parts I suggest ordering from a supplier on eBay. Only the circuit board you will have to find at Radio Shack if there is one locally or use a different prototype board. While you are ordering parts pick up more then you need, these parts are useful to have on hand. You will need: - 1x Radio Shack Printed Prototype Board - 2x 8 pin IC Socket - 4x tactile switch - 4x 10k ohm resistor - 4x 470 ohm resistor - 4x 3mm LEDs - Solid core wire - CR2032 battery and holder - NPN and PNP transistors to test.

Only US$15.52, buy best original hiland diy m12864 graphics version lcr esr pwm transistor tester kit sale online store at wholesale price. Transistor Tester: The purpose of this circuit is to test NPN and PNP transistors and to identify their pin layouts, ie ECB, EBC. I find myself testing a lot of transistors to determine their pin layout and type and as such find that building the test circuit on a b.

Two 8 pin IC sockets are used to hold the transistors as we test them. Place the first socket one space from the left of the prototype board. The other socket is place two spaces next to the first socket. This spacing will allow us to run wire later so the we can provide power to the testing circuits. Solder the IC sockets in place. While soldering the sockets in place bridge the gap between the following pins and the nearest voltage rail. Starting from the left, pins 1 and pins 6 top and bottom.

See the pictures for a better explanation. To bridge the gap solder the IC socket in and then place a bit of solder on the voltage rail closest to the pin. Now touch both the IC socket pin and the voltage rail with the soldering iron tip and apply more solder until the connection is made. Go slow so that you do not bridge pins that you would not want to connect. Remember you are only connecting 4 pins!

NOTE: I would show a picture of the pins bridged but I did not bridge them until I was building each test circuit. Take a look at the final solder layout in step 6 of this Instructable if you are still having trouble. Lets work on one test circuit at a time. We will start with the NPN transistor with a pin layout of EBC; Emitter, Base, Collector.

Place the 10K ohm resistor in a horizontal orientation so that it connects to pin 2 on the IC socket and extends to the last pin on the left of the board. Place the 470 ohm resistor on the 3rd pin of the IC socket in a vertical orientation. Solder the resistors in, if you are using new resistors or have resistors with long leads do not trim them yet. We will use these leads for future connections.

Now to place the switch and LED in the circuit. The switch will provide positive power to the 10K ohm resistor. Place the switch with one pin farthest to the left so that it aligns vertically with the resistor. If you have a switch with 4 pins make sure you place it so that the connection will be broken between the left and right set of pins. Solder the switch in place. Now you will need to bridge the gap between the 10K resistor and the switch.

If you had long legs on your resistor bend one now so that it touches the switch connection. Solder and then trim this connection. If you did not have long legs on you resistor you will need to bridge the gap in a similar way that we did with the IC sockets and the voltage rails. Now place the LED in the circuit between the 470 ohm resistor and the right pin of the switch. Place the LED so that the anode, +, connection is connected to the pin on the switch.

The graphics is good also. THREE STARS because after reaching tech 8 you need at least a epic weapon for story. Unkilled youtube.

Solder the LED in place. Using the LED leads bend the anode so that it touches the switch pin to create a connection between the two. This is where the positive power will split off. Bend the cathode of the LED so that it connects with the 470 ohm resistor. Solder these two connections.

Now lets provide positive power. Run a wire from the positive voltage rail to the second pin from the bottom. Now run a wire from the wire we just placed to the connection between the LED and switch. Solder all connections. Now place a NPN transistor in the socket as show and push the button.

If the transistor works the LED should light up. Do you have the correct Transistor? Is your circuit connections correct? Now that you have built the tester it is time to find out how to use it. There are two main types of situations you will encounter.

Situation 1: You know the transistor type and orientation. If you know the transistor type and orientation place it in the correct testing circuit. Hold the tester in the landscape position with the battery on the right side. Place the transistor in the correct circuit for its type and orientation with the flat side facing you. With the transistor firmly in the socket press the tactile button. If the LED lights up the transistor passes the test.

Situation 2: The transistor type and orientation is unknown. Start with the tester in a landscape position with the battery to the right. Place the transistor in the bottom left circuit, the circuit that tests if it is an NPN with an EBC orientation. Make sure to place the transistor in the socket with the flat side facing you. With the transistor in the socket observer the LEDs status without pressing the button, don't touch it just yet.

Is the LED on? If so then the transistor is a NPN type but does not have the EBC orientation.

Remove it from the socket and place it in the socket to the right to test if it has the orientation of ECB. Is the LED off? Press the button and observe the LED status. If the LED turns on they you have found out three things about this unknown transistor. One it is of type NPN. Two if has an orientation of EBC and three it works. If the LED remains off with or without pressing the button place it in the PNP testing circuit and try to determine the orientation.

The main thing to take away from this situation is that if a transistor is placed in the correct transistor type testing circuit but the wrong orientation the LED will illuminate. This holds true for both NPN and PNP test circuits. By observing this you will know if you have guessed the correct transistor type but chose the wrong orientation. Knowing this can save you a lot of time when you are testing a pile of unknown transistors. NOTE: In handling this tester you may have noticed something odd happen if you touch the back side of the circuit, specifically bridge the switch with your finger.

If you do this with the correct transistor in the socket the LED will light up without pressing the button. Don't worry nothing is wrong with your circuit or the transistor, in fact this is good.

Your finger is conducting a small amount of current which is picked up by the transistor. The transistor, doing one of the things it is designed to do, picks up this small current and amplifies it by letting current pass through to the LED. So while handling the tester try to keep your fingers from brushing the back of the tester to prevent false readings. There is a wide variety of simple bipolar transistors.

When I go to buy some, the salesperson usually asks: plastic or metal even for such an elementary device as the 'workhorse' 2N2222. Google 'Mouser Electronics', a well known electronics distributor. Go left to 'Product Finder'. Click on 'Discrete Semiconductors' and then click on 'Transistors Bipolar' and 'Show Products'.

Select page 4 and look at left images 13 and 14 from top. The 6th column from left says 'Data Sheet' (click to open)and you will see a TO 92 package (plastic) and TO 39 package (metal) respectively. Kind of confusing. The article deals only with plastic packages. When it comes to metal (TO39), my rule of thumb is that the lead physically closest to the metal tab is the Emmiter but I am not sure that this is always true. It is easy to add stuff when others have done the hard work.

I respectfully submit the following comments (in several messages). 1) There is a standard numbering system for IC sockets that avoids any possible confusion.

It is based on the half circle notch (indent) in the plastic frame seen pointing downwards on the parts picture (shown under Step 1). (A) Place the socket in front of you so that the slots will be in two horizontal parallel rows. (B) Orient the socket so that the half circle notch is at your left. (C).Starting from the left on the lower row, the slots are 1, 2, 3.x. When you reach the end of the lower row, jump counter clock wise to the top row and continue numbering x+1, x+2. If you have to insert an IC, look at its top surface and you will see a tiny embossed circle (ususally) or some other mark. That mark must point the same way as the half circle notch.

I think I have a solution for you: Problem 1: From the simple test schematic I have the base of all the transistors are connected to the 10K resistor. In this schematic the base pin is always drawn as the middle of the three transistor pins. No when we go to real life components the pin layout is not the same. For the bottom right transistor the pin layout from left to right is; Emitter, Collector, Base.

So the base moves from the middle pin to the right pin. Problem 2: The picture in step 6 appears to be playing tricks on my eyes. It looks like the bottom right LED has a flat facing up. I am sure this is not the case. Just make sure to place you LED with the correct polarity. I like to use a button cell to quickly check the polarity of LEDs before placing them, I never trust the makings on any of the LEDs I pull from old electronics.

Many many thanks for the extremely appreciated help as i really need to make this tester circuit especially as it uses very simple components for a complete noob like me, i am so very grateful for the extra help!!! Kitchen scramble loveville. Obviously your circuit works as others have made it too and even made some changes but because ive only just started learning electronics this year its playing havoc with my old brain trying to learn new tricks, lol! I'll be resuming this project over the weekend and am quite determined to make an enclosure for it as well because of the great practical use of this very important circuit!!! Once again many thanks for your kind patience with assisting a complete noob and making it a few good steps closer for me to make this awesome circuit!!!;-).