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Forum Index : Electronics : transformer output
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| irishron40 Senior Member  Joined: 22/09/2014 Location: IrelandPosts: 251 |
Hi. I have a large transformer which is able to give me 38vdc It came out of a VP-1240B Power Amplifier can anyone tell me what amp output this transformer is able for? I think its able to supply 15 amp, but not sure I like to use it for Downwind variable power supply based on lm723 http://www.thebackshed.com/forum/forum_posts.asp?TID=2249&KW=lm723 thank you 
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Were there any fuses on the input or output? The fuse rating would give you an idea. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
Thx Glenn the fuse was after the 2 rectifiers and is rated 20A Transformer is about 6x6 inches in size. quit heavy too ron |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
In that case it should handle 15 amps then. Just keep an eye on its temperature. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
i will Glenn. It also had 2 large cooling ribs 8x4 inches. I love salvaging old electronics. thx again. ron |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
On average the DC output is calculated from the AC output like this ... 26VAC x 1.4 = 36.4VDC So your 38VDC is in the ball park but might not be sustainable under load. I too would think you should be able to get 10 amp or above from the transformer. Note the circuit design presented is only rated to 10 amp, and at that high current you will need LARGE heatsinks on the transistors. Sometimes it just works |
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| irishron40 Senior Member Joined: 22/09/2014 Location: IrelandPosts: 251 |
thx I think this heatsink should be large enough to handle those resistors 
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Actually its about the ideal size, being about twice the size you need for 10 amp at 35VDC input. It is the Transistors mounted to the heat sink and not resistors, although it wont hurt to also mount the 10W resistors on the H/s. Sometimes it just works |
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