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Old 20th Sep 2019, 11:54 am   #1
radioman
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Default Texas Instruments Bridge Rectifiers

Hi,

I came across these 35mm square bridge rectifiers amongst a stash of components I got at a 'junk' sale.
Given their size and type numbers (1B20K10 & 1B20K20) I had hoped they'd be rated for 20A or so.
However, I've just found out from an on-line datasheet that they're only rated at 2.0A !
If this is correct I can't understand why they're so BIG !
Any thoughts ?

Andy
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Old 20th Sep 2019, 12:10 pm   #2
barrymagrec
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Default Re: Texas Instruments Bridge Rectifiers

They are very old designs. I seem to remember one of these in a Roband PSU from around 1962.
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Old 20th Sep 2019, 12:51 pm   #3
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Default Re: Texas Instruments Bridge Rectifiers

Back when they were made, anything for high voltage was much bigger than it was today.

Also, that series ranged from 50 to 800volts (all at 2A), so it was probably a standardised package of the time.
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Old 20th Sep 2019, 1:53 pm   #4
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Default Re: Texas Instruments Bridge Rectifiers

OK fair enough, I didn't realise that they were that old, they must be early silicon types.
Thanks for the comments.

Andy
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Old 20th Sep 2019, 3:10 pm   #5
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Default Re: Texas Instruments Bridge Rectifiers

A 20 amp device would probably be in a metal case.
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Old 20th Sep 2019, 4:45 pm   #6
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Default Re: Texas Instruments Bridge Rectifiers

HI, Radioman,andy.

Would a 25A be Suitable for you, have a look at Data sheet 26MB60.
they are not cheap but if you really need them I will send you two Nos/FOC.
you pay postage.

PM your address Gezza123
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Old 20th Sep 2019, 6:14 pm   #7
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Default Re: Texas Instruments Bridge Rectifiers

some of the early bridges were just potted-up wire-leaded diodes - note the turret tags. More a convenience item than anything special.

Beefy ones need heat sinking, with an aluminium outer case or just an aluminium base. Plessey moulded some onto short bits of aluminium angle (and did a similar audio amp... I think Clive got the rejects )

David
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Old 20th Sep 2019, 9:53 pm   #8
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Default Re: Texas Instruments Bridge Rectifiers

Quote:
Originally Posted by gezza123 View Post
HI, Radioman,andy.

Would a 25A be Suitable for you, have a look at Data sheet 26MB60.
they are not cheap but if you really need them I will send you two Nos/FOC.
you pay postage.

PM your address Gezza123
Hi Gezza123,

Thanks for that offer but I don't need one with that high a voltage rating.
I was only trying to identify what I had acquired and confim the specification.
I'm sure I've already got a 25A one somewhere - just need to find it !

Cheers,
Andy
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Old 21st Sep 2019, 2:56 am   #9
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Default Re: Texas Instruments Bridge Rectifiers

The diodes in early bridges are often quite slow types and prone to generate broadband RF noise. It sounds bizarre, but they can be noisier than an SMPS.

David, (G-QRP 3252)
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Old 21st Sep 2019, 8:05 am   #10
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Default Re: Texas Instruments Bridge Rectifiers

And only 200v PIV which is a shame, still they'd be ok for small low powered circuits though the turret tags mean they can't really be mounted on a board, still worth keeping though.

I have some of the older diodes and looking at the specs of a lot of them, they really are c**p, EG 40v 400mA. Diode/rectifier tech has come a long way since.

Andy.
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Old 21st Sep 2019, 10:51 am   #11
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Default Re: Texas Instruments Bridge Rectifiers

Absolutely - OA211 - 0.5 amp, Stud mounted!
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Old 21st Sep 2019, 11:21 am   #12
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Default Re: Texas Instruments Bridge Rectifiers

Quote:
Originally Posted by Diabolical Artificer View Post
... the turret tags mean they can't really be mounted on a board, still worth keeping though...
Andy.
They can be pcb mounted, but you need some really big holes
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Old 21st Sep 2019, 2:27 pm   #13
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Default Re: Texas Instruments Bridge Rectifiers

Poor wee (or not so wee) bridges. Not many amps, not many volts for their size and likely to be noisy.

Packing washers? Or just steering gates in a low-power dual supply application.
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Old 22nd Sep 2019, 11:55 am   #14
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Arrow Re: Texas Instruments Bridge Rectifiers

1B40K20: 4 amps, 200 v. I have a bag of 15 of these, none of which I have used for decades - and I don't anticipate that I will be using them - ever. Some have been used; some haven't (no solder on their tags).
Free to anyone who wants them: you pay for the postage only.

Replies by P.M., please.

Al.
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Old 23rd Sep 2019, 8:27 am   #15
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Default Re: Texas Instruments Bridge Rectifiers

I've got a couple of the 4A ones as well... so no need here.
Perhaps you should advertise them in the 'Offered' section of the Forum, I'm sure someone will want them !

Andy
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Old 23rd Sep 2019, 9:00 am   #16
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Default Re: Texas Instruments Bridge Rectifiers

Quote:
Originally Posted by Radio Wrangler View Post
The diodes in early bridges are often quite slow types and prone to generate broadband RF noise. It sounds bizarre, but they can be noisier than an SMPS.

David, (G-QRP 3252)
Would a 3N255 be noisy too ? I've one or two pulled ones that I'm hoping to use in my project.
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Old 23rd Sep 2019, 1:11 pm   #17
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Thumbs up Re: Texas Instruments Bridge Rectifiers

Quote:
Originally Posted by radioman View Post
Perhaps you should advertise them in the 'Offered' section of the Forum, I'm sure someone will want them !
Thanks; good idea; will do.

Al.
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Old 23rd Sep 2019, 1:26 pm   #18
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Default Re: Texas Instruments Bridge Rectifiers

Quote:
Originally Posted by Jolly 7 View Post
Would a 3N255 be noisy too ? I've one or two pulled ones that I'm hoping to use in my project.
It depends what you call noisy. They will be fine for some applications, but not others. Fast diodes are very cheap, so it's a mistake to use old scavenged parts if noise is likely to be an issue.
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