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Diode Checking

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J

John Schmincke

Member
I just picked up 2 of these 25amp/50V rectifiers. I would like to test them to see that they are good after installing a new cutout that doesn't cutout. Can this test be made with a battery charger ( what goes in comes out the same ) or best to use a vohm with a diode setting? This is getting interesting.
Thanks,
John
 
About the best way I have found to test a diode is this. Take a light bulb say a 12 volt one and a 12 volt battery and use that to test a diode. Hook it up one way and the bulb should light up and then hook it the other way and the bulb should not light up. Simple test but works better then most cheap meters.
 
Diode is basically a one way valve.
Current flows one way and not the other.
Did you buy a diode or a bridge rectifier?
A bridge is basically four diodes, but the hookups would
be different as compared to checking a single diode.
 
I learned that trick from another guy on here. George Marsh who posts on here on and off. I tried my meter and found it said diodes where bad but doing it with the light bulb said good and sure enough they where good
 
Royse, I bought two full wave bridge rectifiers. I checked them with a digital multi that showed 467 consistant on both units. I understand from a U-tube vid I found it's suppose to show between 400 - 600 so I guess theyre good. Never worked with one of these things before, don't understand them yet as they are submersed in black silicant or something...can't see the diodes but do understand they are as you mentioned, like one-way valves. Just goes to show how some people get around a poor design like these magnetic cutouts and then spread the knowledge wealth for others to benefit from. Pretty neat!
 
Hi Old, Well, maybe I guess. But what if you have a open diode no light = no light? while a shorted diode would pass currect lighting the bulb but current would still drain the battery back into the genny? I don't know, just a guess.
John
 
Well if shorted ye it would light both way so it would be a bad diode and if an open and no light at least one way again bad. Light one way and not the other then good simple as that
 
Four posts on your rectifier right?
And you're measuring between two of them.
Just switch the meter leads on the same two posts and it
should read open in the opposite direction on the proper scale.
Same as what Old was saying, it should let current flow and
light his test light one way, but not the other.
Some meters are not well suited for testing diodes.
Good thing is you have spare cut-outs built right in if one fails
since you'll only be using 1/4 or 1/2 of one of those units. :)
 
This past summer I was working on a couple battery chargers and ran into the meter saying the diodes I had where bad but after George told me to try the light bulb and battery I found my meter did not work well on the lager diodes as in the 50 plus amp ones I was checking
 
That's right Royce, four posts. Makes sense reversing the leads on the same 2 posts. I have to wonder though...whats the difference between AC on the one post and + on the other post? This means the 2 posts opposite those are - ( minus )? or the pass-through post? It's now been 29 years since I built a o-scope to test scratch built computers a computer science doctor designed for India to locate water underground ( temp reading systems ). I calibrated them with this scope as well as Johns Hopkins gear in the basement of the hospital in Baltimore that had to be tweaked weekly. Damn near forgot everything is what I'm discovering now that I found properties 30 years ago that have a need for commercial signage....scarey when I think about it!
 
Yea. I just discovered my $19.00 GB Instruments meter didn't communicate well with my DieHard 6/12V charger. I think your on to something with that 12V bulb you mentioned.
 
(quoted from post at 01:46:10 12/23/13) That's right Royce, four posts. Makes sense reversing the leads on the same 2 posts. I have to wonder though...whats the difference between AC on the one post and + on the other post? This means the 2 posts opposite those are - ( minus )? or the pass-through post? It's now been 29 years since I built a o-scope to test scratch built computers a computer science doctor designed for India to locate water underground ( temp reading systems ). I calibrated them with this scope as well as Johns Hopkins gear in the basement of the hospital in Baltimore that had to be tweaked weekly. Damn near forgot everything is what I'm discovering now that I found properties 30 years ago that have a need for commercial signage....scarey when I think about it!
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his help?
 
I have 3 of the bigger up right roll around chargers that I was working on. 2 of them now work and would not be if I had not found out about the light bulb test for diodes.
 
I'd like to say yep but really, no. Guess I'll stick to Olds method with the light bulb. I'm gonna research these rectifiers till I get it though. I have 2 studer reel to reels I want to freshen up so it will come to me eventually. What I'm missing everytime I look at one of these rectifiers is there seems to be some graphics missing. Shows AC and + one on ea leg. Two legs with no markings, no in-out, arrows, nothing. Thats where I'm stumped but the bulb will show me.
Thanks JMOR,
John
 
(quoted from post at 12:55:32 12/23/13) I'd like to say yep but really, no. Guess I'll stick to Olds method with the light bulb. I'm gonna research these rectifiers till I get it though. I have 2 studer reel to reels I want to freshen up so it will come to me eventually. What I'm missing everytime I look at one of these rectifiers is there seems to be some graphics missing. Shows AC and + one on ea leg. Two legs with no markings, no in-out, arrows, nothing. Thats where I'm stumped but the bulb will show me.
Thanks JMOR,
John
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You have four terminals. Two terminals are labeled with a ~ graphic - those are the AC line in connections. You have a - terminal and a + terminal that are the DC line out connections.

TOH
 
Thats where I got stumped. There are no graphics like the ones you mentioned or the ones I saw in the diagrams. You can see one online, its part #GBPC25005 or radio shack # 276-1185 It only shows AC on one leg and + on another. Nothing else. Now I know this means something to you guys but till I find a bulb to test it, Im stuck. Current will only travel one way. That I understand.
 
Diodes like capacitors can be hard to check so this new way for diodes I'll use lot more. Years ago I was a Navy E.T. and repaired computers but they never gave us the battery light bulb test idea
 
If none of the terminals are labelled, one of the corners of the package should be clipped off. That is the +DC output leg. The one diagonal (or 'catty cornered') to it is the -DC output. The 2 others are the AC inputs.
 
(quoted from post at 13:38:46 12/23/13) Thats where I got stumped. There are no graphics like the ones you mentioned or the ones I saw in the diagrams. You can see one online, its part #GBPC25005 or radio shack # 276-1185 It only shows AC on one leg and + on another. Nothing else. Now I know this means something to you guys but till I find a bulb to test it, Im stuck. Current will only travel one way. That I understand.
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JMOR gave you a labeled diagram for the GBPC module. You only need one DC terminal and one AC terminal to define the hookup. The diagonals are the matching terminals. No need to make it any more complicated than that.

TOH
 
Well if you really want to get dazed and confused start messing with things like And gates or Nor gates or do the binary to octal math of the old computer systems. Doing a lot of that will sure test your brain power or smoke your brain power LOL. Then there is the Or gates and nand gates. All have to do with old computer systems
 
(quoted from post at 14:47:11 12/23/13) Well if you really want to get dazed and confused start messing with things like And gates or Nor gates or do the binary to octal math of the old computer systems. Doing a lot of that will sure test your brain power or smoke your brain power LOL. Then there is the Or gates and nand gates. All have to do with old computer systems
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Nothing has changed - binary logic circuits are still the basic building blocks used in digital computers. Just a lot more densely packed onto silicon. The binary, octal and hexadecimal number systems are still with us as well......

TOH
 
I did Old. I built a conversion board with LED readouts to convert numbers to binary or hex and one other I dont remember now. Got so I could see labels in the stores and convert them to binary in my head..became a game after awhile. Started seeing chips as tiny cities with clock speeds and destinations to determine which was needed for a given application. Didn't care much for diffy q's though...too much theory and imagination involved.
 
Ya I got out of doing electronics years ago because I learned to hate doing it. I hate working on something that you can not see and hear working that is why I play with engines now days
 
I no the binary is used since a computer pretty much can not count past 1 but thin is you think about it we humans only count to 10 and then we use multiple's of 10. Ya lots of people do not understand the switching circuits that make a computer do as it does and back when I worked on computers they took up as much if not more room then a house fridge
 
(quoted from post at 15:01:32 12/23/13) As well as is cobalt. They predicted it would die 40 years ago. Still runs the mainframe for citibank in brazil and many others.
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That would be Cobol. Millions if not billions of lines of legacy code still running although it is slowly being ported to newer languages. Not a lot of experienced Cobol programmers left and if you have those skills you can command a surprisingly high salary maintaining those legacy systems....

TOH
 
(quoted from post at 15:06:58 12/23/13) I no the binary is used since a computer pretty much can not count past 1 but thin is you think about it we humans only count to 10 and then we use multiple's of 10. Ya lots of people do not understand the switching circuits that make a computer do as it does and back when I worked on computers they took up as much if not more room then a house fridge
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Computers can count well past one. They do it using the binary (base 2) number system and binary logic units.

The ancient Sumarians counted using the sexequismal (base 60) number system. Other ancient civilizations used number systems with a variety of different bases.

Modern humans count using the decimal (base 10) number system probably because we have 10 fingers and found it to be the most natural.

Because written binary number representations are too long to be easily manipulated on paper and digital computer memory is typically addressed in groups of 8 bits called a byte programmers prefer octal (base 8 ) or hexadecimal (base 16) for written representation of digital data.

If you have a Windows PC the calculator program that comes standard with the system will do decimal, octal, and hexadecimal arithmetic for you.

TOH
 
Sized proportional to the -what were they? 8" floppys and word star!!!!! that was exciting once.
I had a 7 channel tape drive that the tape rode on air. Freq resp of something like 2 - 270,000. Was real good at playing back satellite lingo with speeds from 2.5 to 160 with with 7 o-scopes for channel freq meters. Had a remote control that looked like something used for a freight elevator.
 
I didn't but my wife did. She wrote the software for Citibanks credit card dept and human resources in Sao Paulo for almost 20 years. Came here and would like to return to the field but Lockheed and many others feel shes been away for too long.
 
(quoted from post at 15:55:33 12/23/13) I didn't but my wife did. She wrote the software for Citibanks credit card dept and human resources in Sao Paulo for almost 20 years. Came here and would like to return to the field but Lockheed and many others feel shes been away for too long.
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That's what I meant when I said "if you have the skills". Modern Cobol applications are nothing like the Cobol of the 80's or for that matter even the 90's. In this business if you take a 5 year hiatus you lose a lot of ground. I have been retired just about of 2 years and 7 months (who's counting ;-)) and I already see the gap when I talk to my still working colleagues. I am at the point that if I want to hang out my consulting shingle I need to do it NOW. Another 2-3 years and I will be so far behind nobody will be willing to pay enough to make it worth my while....

TOH
 
(quoted from post at 15:03:10 12/23/13) no legs are clipped...all identical. Part # 276-1185 radio shack. You can see them online.
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John, I think mbramble meant one corner of the case
would be clipped, not the lead, the case itself.
Any two terminals that are next to each other should work.
You just need to test to see which way current will flow so
you hook it up in the right direction.
 
I thought about that also Royse but the case has slightly rounded corners on all four sides while all four leads are identical. It's not like the one in the pics were one corner is clipped off.
 
Thanks TOH, I got her to read this to confirm she needs to forget cobol. She is studying apps though and the software kit she just installed on her own here at home. I think it serves android. Beyond me at the moment. She says thank you for the confirmation though. Her friends back in Brasil she worked with took a hiatus to open their own businesses had a tough time returning after several years also. Some succeeded, others bailed out.
 
Mine is not like that. Same price, same part #, interesting...mine came from where or where were those made? Wish I knew how to post a pic here if you want to see it.
John
 
The sub I was on had a mag tape unit that used reels around 21 inch in diameter and bot what a pain in the back sides to get info off of. I worked in the Nav control room on a FBM sub so we where the guys who told them where the sub was so they could shoot the missile where they wanted it to go
 
What they have now days maybe but the computers I worked with only knew a 1 or a zero so they counts to 1 then the next up was well you should know that of course the counting thing is one of those things few would ever agree with since as I said we humans use the base 10 so we count to ten then multiply from there
 
Wife just returned from shopping. Stopped into another radio shack and asked for this same 25amp 50 V rectifier. They had 6 and these have the clipped corner like mbramble supplied a pic of. She returned my 2 and got 2 of these. Guy in the store thought nothing about the corner differences but was happy to make the switch. Now I guess I can get on with this project and refer back to everyones notes about procedure. I'll post back to let all know how it goes.
Thanks everyone...been a great chat.
John
 
(quoted from post at 17:46:27 12/23/13) Wife just returned from shopping. Stopped into another radio shack and asked for this same 25amp 50 V rectifier. They had 6 and these have the clipped corner like mbramble supplied a pic of. She returned my 2 and got 2 of these. Guy in the store thought nothing about the corner differences but was happy to make the switch. Now I guess I can get on with this project and refer back to everyones notes about procedure. I'll post back to let all know how it goes.
Thanks everyone...been a great chat.
John
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ot every maker uses the same scheme to ID the + terminal. In the mbramble link, you can see one bridge unit which has all 4 square corners, uses flat spade like terminals and 3 are in alignment & the 4th is oriented differently. Want to guess what that lone ranger is?
 
JMOR - Heck I was having a time with this one so no, I have no idea what that might be. The wife just picked up 2 more from a different store (still radio shack) that has the same part # and same price of $4.49ea but these have a clipped corner on one edge. Gonna refer to the notes here to proceed with this one.
 
(quoted from post at 22:48:26 12/23/13)
(quoted from post at 18:28:07 12/23/13)
(quoted from post at 21:55:01 12/23/13)
(quoted from post at 17:46:27 Want to guess what that lone ranger is?
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DC+ final answer. What do I win??
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ou get to pickup one free sweet potato at the sweet potato festival next year. Alba/Golden I believe.
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As long as it's big enough to make a pie :lol: I recognized that type of rectifier from using them on Triumphs to eliminate the zener diode and rectifier. That odd turned blade always stands out.
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Triumphs! You go back a ways with your tinkering?
My first new car almost was a TR4. So the odd turned blade was the give-a-way...interesting. Yea, I want to put one on my 2N to eliminate the magnetic cutout. Thought I'd mention that as no tractor related topics have cropped up.
 
No reflection on you bro but that's going back a ways. I was drinking milk back then...only remember ozzie & harry...oh, that's todays version.
 
(quoted from post at 23:46:25 12/23/13) Triumphs! You go back a ways with your tinkering?
My first new car almost was a TR4. So the odd turned blade was the give-a-way...interesting. Yea, I want to put one on my 2N to eliminate the magnetic cutout. Thought I'd mention that as no tractor related topics have cropped up.
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What got me thinking was a couple of years ago I was doing landman work in Pa. We had an appointment to take water samples at an old farm that a Dr. had bought for a weekend home. I was talking with the owner, while the people took their samples, and he told me it was the old Zener family home. I told him the only Zener I'd heard of was the diode guy. "That's him" he said, so I got to see Zeners library and study. Lots of his old books and notes were still there.
 
Wow!. Did you get a chance to dive into some of the notes? These things only happen once in a lifetime for most of us. Bet that was a interesting property.
 

Didn't really get to look at anything. I'm probably better off :lol: Most of the place was left as is. 2 or 3 rooms were kind of modernized. There was a nice view from there and fruit trees, grape arbors, etc. Pretty old place as in pretty and old and pretty old.
 
Oh! mid 70's. Last name starting with S, I was 365 on the draft list. They got up to 362 one night. Realizing later I was my dads only son. Guess that's why I never heard another word from them. Never even got called for a physical. Missed out on a lot from what I've heard.
 
My draft card came up 1-A so it was join or go to school or be drafted. I joined. My high school grades had me low on the testing but my SAT scores had me high and the test I took for the Navy had me going where ever I wanted to go. At the time I enjoyed messing with what I call zap-u-trons but soon learned to hate them
 
(quoted from post at 17:34:21 12/23/13) What they have now days maybe but the computers I worked with only knew a 1 or a zero so they counts to 1 then the next up was well you should know that of course the counting thing is one of those things few would ever agree with since as I said we humans use the base 10 so we count to ten then multiply from there
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Well I am a human, mathematician by training, and a computer scientist by profession and I see it a little differently.

0000
0001
0010
0011
0100
0101
0111
1000

In that sequence I counted to eight by one starting at zero using binary (base 2) notation to "keep the count".

00
01
02
03
04
05
06
07
10

In that sequence I also counted to eight by one starting at zero but used octal (base 8 ) notation to "keep the count"

Mathematicians have devoted entire lifetimes to the study of the counting numbers and their properties - e.g the abstract set of Integers - and are in total agreement on how they work. Specifically it is an infinite set and allows us to count without upper or lower bound regardless of the notation we use to keep track of "the count".

Computers are counting machines built by humans to help them count. Computers count using the binary counting system (base 2) and use electronic "bits" inside the machine that are either ON (1) or OFF(0) to keep track of the count. In that regard a modern computer is no different than the ancient abacus which, depending on the number system that was in vogue in the society that built it, used some number of beads (the base number) on a series of strings to "keep the count".

In the 50's and very early 60's the integer arithmetic units inside a computer (AKA the "accumulator") were generally 16 bits long and the upper bound on a computers ability to count was 65,535 (decimal). By the late 60's we were up to 32 bit arithmetic units and the upper bound was 4,294,967,295 (decimal). The 90's saw another exponential leap when we started building computer's with 64 bit arithmetic units and the upper bound on their ability to count went to 18,446,744,073,709,551,615 (decimal).

So please - do not confuse the written notation or the electrical/mechanical means used by either humans or machines to keep track of "the count" with the mathematical process of counting.

TOH
 
Now see this is a case of the glass half full or half empty.
The way I was taught numbers the computer counts to 1 then ten etc as per Navy E-T school As for base ten again the way a person is taught is not the same all over and again I was taught 10 then from there it is muliapals of ten. Does not matter what or who you are what matter in this case is simple teaching and ya you maybe a college educated guy but in this case it is a mute point
 
(quoted from post at 10:34:48 12/24/13) Let us not forget that there are those that overheard a few
buzzwords here and there and then throw them around acting
like they actually know something, but their charade crumbles
when they indulge in conversation with someone who actually
knows something. Excuses begin to bloom !
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I think the one aspect of science/mathematics that I have always found most amazing is the incredible innate intelligence of the people who started it all. Some ancient genius - and I do mean genius - was sitting around counting his sheep or chickens or whatever one day and dropping pebbles or something similar into a sack to make a record of how many he had. And everytime he or some wild animal ate one of those sheep or chickens or whatever he took a pebble out of the sack to update his count. And everythime on of the sheep had a lamb or an egg hatched he added a pebble to the sack. You get the picture I'm sure.

And in that process he started started thinking about this counting thing. And as he thought about it he realized that there was a real system to it. And he started really thinking hard, did some scratching in the dirt, started dividing piles of pebbles and sticks up to see how it worked on more complex problems and on his own, with no help from anyone, he learned the very basics of number system theory. I don't know about you but I think this dude was incredible.

Now he was really excited and he created a crude counting machine to help him count faster and more accurately. He shared what he had learned about counting with his friends and and showed them his counting machine but most of them didn't understand what he was talking about. But a few did and they took what he had explained to them and did some more heavy thinking about this counting thing on theri own. They built better counting machines. Sometimes thay had to go back and ask the first guy to explain it again or differently because the concepts were abstract and hard to understand. And in that process they learned some new things that the first guy didn't think of. And over a short (by human civilization standards) period of time that thinking and sharing process developed the basic foundation of mathematical number systems 4000+ years or more BC. All because some guys that didn't even know they were mere specks on a planet orbiting a sun that was itself a mere speck in a much larger universe did some real thinking about the enumeration process we call counting.

So today we continue to teach these very same principles of enumeration to our children and friends and sometimes we succeed but more often we don't. That is inevitable and simply part of the human intellectual condition. But the really depressing part is when we give it our best shot and our children or friends simply aren't interested in listening and learning because it runs counter to something they have believed for a long time. That is a real bummer....

TOH
 
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