The transistor is bad and there is no need for further testing. In case a transistor somehow fails the BC testing. Next, we are required to check the BE connection for open and short. If the transistor passes the BC terminal testing. Reverse case: Reverse the multimeter connectionsįor a good transistor, you must get a low reading value in the forward case and a high value in the reverse case.Forward case: connect the black (-) probe of the multimeter to the collector (C) of the transistor.Take a multimeter and select the resistance feature.This theory will help you make your own devices and procedure to test transistors. I believe it is not that hard if you pay close attention. Just take whatever you can and leave the rest. I am writing this article for beginners people. We are not considering CE because if we get one of the three terminals bad then there is no use in wasting time on the rest.īut if we get two terminals rights then for sure we will of course test the CE connection. Because in this method we will be measuring the resistance between the terminals.įollowing are the possible combinations we can work on for NPN and PNP.Īmong the above, the BC and BE terminals are important. I mean if the terminals are open or short, then we can for sure say, the transistor is faulty. The next theory that we can use for transistor testing is to check if the terminals are in fine condition or not. With that feature, all you do is put your transistor into the multimeter and get the beta results on the screen. All you require is a digital multimeter with a transistor testing socket. Now, the question is, is there any easy way to get this beta value? Yes, there is. If they match you have a good working transistor.
Make the above circuit (to the right) on the breadboard and take the readingsĪfter careful measurements put the value in the formula of transistor DC gain.Ĭompare the gain value with the value from the datasheet (search online by typing the transistor number).Set the multimeter to Milli current mode.Make the above circuit on the breadboard and take the readings.Set the multimeter to microcurrent mode.Please follow the procedure very carefully. You need a good digital multimeter for this experiment. The following is the simple circuit setup for this process. The answer is simply by measuring the ratio of the collector to the base current. The question is how we can effectively measure the gain value. So, a bad or degraded transistor can have a gain less than its provided datasheet value.Īnd we can use this theory to actually test a transistor if it is a good one or the badly degraded one. In amplification, a weak signal is multiplied by the gain value of a transistor. Basically, a transistor is a three terminal active device that serves the following functions:Īmplification has to do with transistor gain.
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