First PSU Build help!!!

[yatesw]

I am a little lost.

I bought and soldered a LM3875 chip amp off eBay HERE

I realised I needed a large power supply, so I bought a 300VA 2x25V @ 6A toroidal transformer. THIS ONE

Now here is my problem: written all over the PCB is ac-0-ac / 24-0-24
Which is fantastic, except i only have 3 power terminals. I don't know if you can see in the photos attached as i have a dreadful phone.




Do you think it just want the 0Vs from both supply rails/secondary coils locally grounded?
How should I wire it?

I don't know if this is clear but please try and help!!

 

[DF96]

You need to connect the two secondaries in series so you get a centre-tapped 50V winding - or 25-0-25. The transformer (or its datasheet) should tell you how to do this. If not, post here what information you have (or a link to it) and we will tell you.

In the meantime, make a lamp limiter so even if you get it wrong nothing will go bang.

 

[yatesw]

Data sheet is here: http://www.rapidonline.com/pdf/82719.pdf

If you could possibly tell me what to do with each colour that would be a great help.


I have my Lamp Limiter ready to go!


Will x

 

[AudioSan]

tie yellow and black wire together and connect them to 0V input on the PSU.
Orange and red wire to the 2 AC connections.
on the primary side you need to tie together grey and violet wire and isolat them. blue and Brown is Connected to 230/240V mains.

 

[yatesw]

By isolate them do you mean connect to ground?

 

[yatesw]

Thanks for all the help guys !!

 

[AudioSan]

no don't connect them to anyting. but the connection need to be electically isolated.

 

[DF96]

By isolate them do you mean connect to ground?

If there is a risk that 'isolate' and 'ground' are two (completely opposite) concepts which you might confuse then I suggest you do some more reading before trying to build a mains-powered PSU. Just trying to be helpful!

 

[AudioSan]

ehm. i ment insulated of course

 

[yatesw]

so attached is what i've got!
sorry if the photo is unclear



Still it doesn't seem to give any power any ideas, aside from my cheap PCB?

I have tired wit with a circuit i know to work and still nothing :/

 

[yatesw]

ehm. i ment insulated of course

I quickly realised what you meant don't worry, i wrapped then soldered them and applied heat shrink Thank you

 

[AudioSan]

grey and VIOLET should be connected together. not grey and brown. but is should still work.
disconect the PSU and measure the voltage on the transformer (without shorting it out)

 

[yatesw]

Fantastic. It all works and sounds beautiful

 

[AudioSan]

good to hear

 

[AndrewT]

............
on the primary side you need to tie together grey and violet wire and isolat them. blue and Brown is Connected to 230/240V mains.

no don't connect them to anyting. but the connection need to be electically isolated.

ehm. i ment insulated of course

In the context of your initial post and the two subsequent clarification posts, isolate and insulate can be read as the same meaning. There is no mistake there.

It's unfortunate that the OP does not understand.
But hopefully he is getting closer to safe mains wiring practice.

Yates,
Look up Mains Bulb Tester, sometimes referred to as dim bulb.

Note Audiosan's primary wiring leaves BROWN and BLUE ready for next connection.
This is the standard UK and Europe, MAIN'S wiring colour code for the last couple of decades.

 

[us1070]

It looks like a double of 2 single power transformer

Connecting the yellow and black makes it the ground for the Orange and Red
Orange(ACV) and Red (Acv) will be your Voltage wire.

According to your spec and the image as it shows its not connected
Blue and Violet should go to your Main Negative Voltage and Grey and Brown should go the Main AC positive voltage this will give you 2 single separate power AC voltages

You can also make the double single transformer into a single
Connect blue and brown together and it should go to the Main positive and Grey and Violet connect together and it should got to the Main Negative.

be careful

 

[AudioSan]

As far as i know. there is NO 115V mains in UK!!! It's grey and violet together to connect the 2 primary windings in series and connect blue and brown to 230V or 240V mains!
and yes yellow and black ARE Ccnnected together in the image.

 

[AndrewT]

It looks like a double of 2 single power transformer

Connecting the yellow and black makes it the ground for the Orange and Red
Orange(ACV) and Red (Acv) will be your Voltage wire.

According to your spec and the image as it shows its not connected
Blue and Violet should go to your Main Negative Voltage and Grey and Brown should go the Main AC positive voltage this will give you 2 single separate power AC voltages

You can also make the double single transformer into a single
Connect blue and brown together and it should go to the Main positive and Grey and Violet connect together and it should got to the Main Negative.

be careful

NO !!!!!!!
this transformer is a dual 115Vac Primary and is to be wired for 240Vac use in the UK.

DO NOT wire the two Primaries in parallel.
That will almost instantly and permanently damage the transformer.,

 

[KaffiMann]

NO !!!!!!!
this transformer is a dual 115Vac Primary and is to be wired for 240Vac use in the UK.

DO NOT wire the two Primaries in parallel.
That will almost instantly and permanently damage the transformer.,

Possibly not the transformer (it's just a block of copper wire, over amping would cook it and melt the insulation then it short circuits, over volting MIGHT work fine, pending on insulation used), but certainly the amplifier or the psu board (caps exploding, circuits frying).

230-240V on 115v primary would just mean double voltage out of secondaries. The transformer might work fine, but it's certain death for the stuff connected.

 

[AndrewT]

Possibly not the transformer (it's just a block of copper wire, over amping would cook it and melt the insulation then it short circuits, over volting MIGHT work fine, pending on insulation used), but certainly the amplifier or the psu board (caps exploding, circuits frying).

230-240V on 115v primary would just mean double voltage out of secondaries. The transformer might work fine, but it's certain death for the stuff connected.

NO !!!!!!
applying 240Vac to a 115Vac winding will seriously overheat the winding, even with no secondary connections.

Doing that again for the other 115Vac winding will almost instantly damage the primary windings.
DON'T do it !