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Old 31st December 2012, 08:53 PM   #1
BIA is offline BIA
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Default Help with transformers

Hi im new , i need help .

I have transformer its 240vac , the secondary winding is 0-24vac .

Do i use a Bridge rectifier to get +/- V dc or do i use two diodes ?

Im totally stumped . ;-/
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Old 31st December 2012, 09:20 PM   #2
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Yes.

Look up online

"Full Wave Rectifier"

and

"Bridge Rectifier"

You will not be able to get + & - from a single secondary.

There are tricks to get a "center" point, but that's not probably something you want to do. Are you sure you have ONLY a single secondary??

Two wires? Or Three? Or four?
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Old 31st December 2012, 09:33 PM   #3
BIA is offline BIA
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Two wires , 0-21vac
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Old 31st December 2012, 09:51 PM   #4
BIA is offline BIA
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Default Transformer Help

Hi yes i dont know what you mean by single secondary , all i know is the transformer has an output of 0-21vac , so the Alternating current is bouncing/pulsing along the ground never going negative volts .

So how do i split this into +/- dc ?
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Old 31st December 2012, 10:28 PM   #5
paulb is offline paulb  Canada
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Elliott Sound Products - Linear Power Supply Design
I suggest that you read the entire article.
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Old 31st December 2012, 10:33 PM   #6
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You should use two diodes to form two half wave recifiers. Of course, you need properly sized diodes and caps.
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Old 31st December 2012, 10:53 PM   #7
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Quote:
Originally Posted by bear View Post
Yes.

You will not be able to get + & - from a single secondary.

There are tricks to get a "center" point, but that's not probably something you want to do. Are you sure you have ONLY a single secondary??

Two wires? Or Three? Or four?
You can get two rails from a single transformer using half wave rectification to get each supply.
I know the picture shows two windings but treat as one for your purpose.

Click the image to open in full size.

Last edited by nigelwright7557; 31st December 2012 at 11:02 PM.
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Old 1st January 2013, 12:08 AM   #8
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I believe that Nigel meant to show an earth ground connected to the "ZEROVOLTS" output. If this is not included, I believe that the whole PS can/will float...

-Charlie
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Old 1st January 2013, 01:49 AM   #9
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Get yourself another identical transformer.

Or

Get yourself a proper transformer for the job (which you did not say what it is). Imo half wave rectifier supplies are not normally a great idea...

You might say what your application is, so that folks might give you a better bit of input?
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Old 1st January 2013, 02:06 AM   #10
paulb is offline paulb  Canada
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Quote:
Originally Posted by bear View Post
Imo half wave rectifier supplies are not normally a great idea...
Why? Because you need twice the capacitance?
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