![]() Most failures are catastrophic, rendering the component completely inoperable. ![]() The lack of parameter testing is seldom a problem because these components will have been tested at manufacture and it is comparatively rare for the performance to fall to a point where they do not operate in a circuit. This form of testing is able to detect whether transistor or a diode is operational, and although it cannot provide details of the parameters. However it is still quite easy to perform a simple go / no-go test using the simplest of equipment. While many digital multimeters these days have a specific capability for testing diodes and sometimes transistors, not all do, especially the older analogue multimeters that are still in widespread use. Test meter basics Analogue multimeter How does an analogue multimeter work DMM digital multimeter How a DMM works DMM accuracy & resolution How to buy best digital multimeter How to use a multimeter Voltage measurement Current measurements Resistance measurements Diode & transistor test Fault finding transistor circuits From what you wrote, there might be a wiring error (such as a solder bridge, perhaps) sneak path that allows the reverse active mode on the PNP side to conduct more than it usually would.How to Test a Transistor & a Diode with a Multimeter It is very quick and easy to learn how to test a transistor and a diode with a analogue multimeter - normally this is good enough for most applications. The LED & resistor on the side not being tested should be an open circuit and therefore zero current will flow. You mentioned in Step 10 that sometimes both the NPN and PNP sides get triggered. In the above sketch, connecting the free end of resistor R1 ("Commande") to the negative of the battery will cause the LED to light up. On the NPN side of the tester schematic, you've got the emitter pins connected to the negative of the battery, the base pin connected through its resistor to the positive of the battery, and the collector pin connected through the LED & resistor series combination also to the positive of the battery.įor the PNP side of the tester, it would probably be better to connect the emitter pins to the positive of the battery, the base pin through its resistor to the negative of the battery, and the collector pin connected through the LED & resistor series combination also to the negative of the battery. I think I have seen them for like $8 assembled. The zener reference testers you can get really cheap. ![]() Although I have a zener tester too, and it really isn't that terrible. That makes them more better than some other AVR testers out there. Both have the precision voltage reference, not just a zener diode. It is in my opinion the ultimate AVR TransistorTester. After I built a 2x16 and saw the GUI tester I had to get one for myself. The 2x16 is just as accurate, but not quite as visually appealing. ![]() It is not quite the best, but it is still pretty good ![]() I am only posting this link because it is the cheapest kit I have seen. If you are really into electronics then you owe it to yourself to get one of these kits, and make it. I like scratch built circuits but I have built a couple AVR TransistorTester kits now, and I do have to say that they are brilliant. ![]()
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