How to test a bridge rectifier and diodes the easy way using a multimeter

hi this video is for my electronic students you might want to use a multimeter basic model like this to test a diode this is a discrete diode is a 1 in 4,000 won by the way that's not blood that's marker pen or maybe a bridge rectifier like this one how we can use a multimeter and the principle behind it let's just go back to basics for a moment is diode anode and cathode yes cathode is spelled with the C but the symbol we use okay and when we've got the diode forward biased the current can flow so we'll have a voltage drop but if we turn the polarity of the battery around and trying to have current flow because it's reverse biased it would act as an open switch or an open circuit there's a function built into many meters the diode test so that's one of the ways you're going to use so I would expect as you probably would a diode will drop something like about point seven ish okay so we need to get it forward biased the Graystripe remember is the cathode so that's up the positive side on this way like that okay and as you can see that diode appears to be good we've got the expected or within the expected range when it's forward bias so let's reverse bias it sure enough it's well the one doesn't mean doesn't mean actual value it just means it's out of limits beyond range which is what you expect because like I said earlier it's like an open circuit but if you've got something like this for direct fire that's basically just for diodes in a single package if you have a look I mean you could check the Tate sheet but this one says the DC output or the rectified supply is on that pin there that lug there so that's the positive one so that's that okay now if you were to check they cheat you'll find that C negative positive and then the AC we know that there's going to be a fly out a diode voltage drop across there it's just the same as a circuit so let's just confirm that one's okay so expecting about point 5 there we go and to confirm that it blocks in Reverse you would do that ok that's exactly what I would expect and so this time we could say check this one up here forward bias point 5 just like this one and then you do the reverse as well I'm not going to do it now and then we could test that one so sure enough that one works and once again you test that one in Reverse ok say you work all your way around and you can do them in Reverse as well just to confirm you could even if you wanted to go from here to here so you'll be expecting about 1 volt and sure enough that works

Channel: Pizzey Technology

Views: 85,792

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Id: Yft7US1C9mo

Length: 3min 9sec (189 seconds)

Published: Mon Feb 10 2020