Toroid @ PE

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rabstg said:
Hi All-

Cross over thread from the SS forum.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=129-090

It is a dual output, 5 amp toroid for 7 bucks!! + and - 40 volts for tube buffers and + and - 20 volts for LM38xx's.....

$7!!! Probably cost more to ship it. Joking....

Looks interesting... shipping for 1 is $8.08 and for 2 is $8.78 shipping. :)

I have a friend running an LM3875 amp with a 80vct transformer that I had laying around, but I wouldn't recommend it. I was suprised that the chip would run on rails a little over 50vdc, exceeding the numbers in the datasheet. :att'n: be careful if you intend on trying it :att'n:

This would work great for a leach amp, with 1 per channel. $22.78 shipped for 2 isn't bad at all.

--
Brian
 
8 bucks to ship one???? The solution is to buy 8.


2 129-080 28V CT TOROIDAL TRANSFORMER $5.00 $10.00
6 129-082 14V CT TOROIDAL TRANSFORMER $5.00 $30.00
1 UPS-GroundTrac $13.16 $13.16

Brian... I ran out of time of parsing the 4780 thread. As sold, does your board implement parallel or bridged topology?

Also, I have a cigar box GC nearing completion. Looks pretty cool. Will send pics.
 
Retired diyAudio Moderator
Joined 2002
chipco3434 said:
8 bucks to ship one???? The solution is to buy 8.


2 129-080 28V CT TOROIDAL TRANSFORMER $5.00 $10.00
6 129-082 14V CT TOROIDAL TRANSFORMER $5.00 $30.00
1 UPS-GroundTrac $13.16 $13.16

Brian... I ran out of time of parsing the 4780 thread. As sold, does your board implement parallel or bridged topology?

Also, I have a cigar box GC nearing completion. Looks pretty cool. Will send pics.

parallel. The main goal is for the LM4780 to be more suited for lower impedence speakers. The bridged configuration wouldn't be good at all with low impedence speakers. A bridged/parallel setup with 2 boards for 1 channel would be optimal if you are going for power.

--
Brian
 
Hey what does the 80V CT mean? 80 volts center-tapped? Sorry Im new to transformers.

Would two of these work for brian LM3875 mono block kit.

If I use the 20.2V rails and it has a current of 5.36A,
so 20.2 * 5.36 = 108.272VA which should be enough for each channel? I read somewhere the actual VA would be time 60%
so 108 * .60 = 64VA, 64watts per channels?

Is this correct? Thanks.
 
Hi-

One would be enough to drive a stereo pair of amps so two in mono configurations would be plenty.

As fo your calculations:

I believe "so 20.2 * 5.36 = 108.272VA" is correct.

I DON'T think "so 108 * .60 = 64VA, 64watts per channels?" is correct.

I think what you might have read is 108 * .60 = 64VA, which MAY be correct, but has nothing to do with "watts per channel".
 
I purchased a couple. The labels says:

I/P: 0 - - - 115V 0 - - - 115V 50/60Hz Fuse
___WHT___BLK_ORG___BLUE_________BRN.
WI. 152Deg.C Thermal cut off
O/P:40.4V - - 20.2V - - 0 - - 20.2V - - 40.4V (5.36A)
____RED_____YEL_____BLK____YEL_____RED
_____________________________[50/98]

(Ignore the underscores "_" I was trying to make the text line up properly).

It has dual primaries, but what I'm not sure of is the brown wire for the fuse. Sure, connect one side of the fuse to the brown wire, but how about the other side of the fuse?

I'll have to test the wires with my voltmeter when I get home to see if I can learn more.
 
Hi mikeciz-

I do NOT have one of them to test, but the following would seem to make sense.

White & Black are US standard colors for 110 voltage. White Neutral, Black hot.

Blue & Brown are standard for UK 220 voltage. Blue neutral and Brown hot.

If you are in the US you should use the white ad black wires and tape up the Blue and black UNLESS they are a second parallel set of primary wires that measure the SAME resistance as the white and black set.

If in the UK you should tape the white and black set and use the blue/brown.

NOTE these are possibilities not instructions or directions.

I am basing this strictly from the colors of the wires and the established US and UK standards.
 
rabstg said:
Hi mikeciz-

I do NOT have one of them to test, but the following would seem to make sense.

White & Black are US standard colors for 110 voltage. White Neutral, Black hot.

Blue & Brown are standard for UK 220 voltage. Blue neutral and Brown hot.

If you are in the US you should use the white ad black wires and tape up the Blue and black UNLESS they are a second parallel set of primary wires that measure the SAME resistance as the white and black set.

If in the UK you should tape the white and black set and use the blue/brown.

NOTE these are possibilities not instructions or directions.

I am basing this strictly from the colors of the wires and the established US and UK standards.

I must also stress that I do NOT have one of these transformers, but having experience with transformer production and going from mikeciz diagram, I would disagree with rabstg and say the following:

115V use you should parallel the primaries, i.e. white + orange and black + blue. Then wht/org is neutral and blk/blu is live.

230V use you should series the secondaries, i.e. join black to orange. Then blu is neutral and wht is live.

I'm also a little confused by the single fuse connection. Test with an ohm meter from the brown lead to all the other leads. I suspect that the other side of the fuse may be internally connected to one of the windings.
 
Here's what I found from tinkering with the transformer...

Two seperate primaries just as expected:

Blue & Orange - 2.7 Ohm
Black & White - 2.7 Ohm

The Brown wire labeled "Fuse" on toriod:

Blue and Brown - 0.7 Ohm
Orange and Brown - 2.5 Ohm
White and Brown - no continuity
Black and Brown - no continuity

I still can't imagine what the brown wire's use is for. Most industrial trans. have taps to regulate voltage, but since there is only one extra wire, not two, it still puzzles me. Perhaps these toroids were for some special equipment. I'm going to just tape the brown wire up and ignore it. Should work great!

mike
 
mikeciz said:
Most industrial trans. have taps to regulate voltage, but since there is only one extra wire, not two, it still puzzles me.

That would be my guess, in other words you would get a different voltage on the secondary side if you put 230V across wht/blu than wht/brn (with blk/org shorted of course). But it is no matter since you have already identified how to wire it up for 115V service.
 
mikeciz said:
Here's what I found from tinkering with the transformer...

Two seperate primaries just as expected:

Blue & Orange - 2.7 Ohm
Black & White - 2.7 Ohm

The Brown wire labeled "Fuse" on toriod:

Blue and Brown - 0.7 Ohm
Orange and Brown - 2.5 Ohm
White and Brown - no continuity
Black and Brown - no continuity

This confirms to me what I was thinking when I wrote my last post, but didn't want to say for safety reasons. The fuse is connected in series with the blue lead. Thus:

115V parallel wht/org to be neutral and blk/blu tape together, then brn is live.

230V series blk/org, wht neutral and tape off blu, then brn is live.

CHECK WITH AN OHM METER BEFORE CONNECTING TO POWER

If secondary doesn't give out expected voltage one of the primary windings may not be in phase and need connections swapping.
 
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