Got it but i could not find a proper power supply at ebay ....
You must really suck at searching then. from cheaper to more expensive
20VA : 2x24v or 1x48v with center tap (just connect the middle terminals) - good for the third design in the picture a few posts above.20VA is a bit low but this is a cheap transformer.
http://www.ebay.com/itm/CTFC20-24-Camdenboss-Transformer-20Va-2-X-24V-/360622938744?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item53f6cd5a78 50VA : 2x9v or 1x18v with center tap. Good for about +/- 11v so obviously less output power
http://www.ebay.com/itm/CTFC50-9-Camdenboss-Transformer-50Va-2X-9V-/130877005329?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e78e09e1150VA : 2x18v or 1x36v with center tap. Good for the third design, just connect the middle terminals together.
You
might be able to use it for first design (split supply) or second design, but you'd have to be really careful. 18v will give you a peak of about 26v, the bridge rectifier will drop about 1.5-2v so you're very close to the +/-25v absolute limit of the tda2050, if you ignore that the transformer may output 5-10-15% more at low loads. You could put 2-3 big diodes on each output after the bridge rectifier, to drop the voltage about 2v more, so you'd have +/- 22-23v
http://www.ebay.com/itm/CTFC50-18-Camdenboss-Transformer-50Va-2X-18V-/130891176802?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e79b8db6250VA : 2x12v or 1x24 with center tap. Exactly what you were searching for, this would give you +/-15v
http://www.ebay.com/itm/CTFC50-12-Camdenboss-Transformer-50Va-2X-12V-/130877006916?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e78e0a444100VA 2x24v or 1x48v only for second or third design of power supply. Added because it's cheap for the VA rating and it's good enough to power 2-3 channels in case you want to make stereo or 2.1
for second design , connect the windings in parallel, 1 to 3 , 2 to 4, and you have a single 24v transformer with twice the current capability. use bridge rectifier and capacitors to get about +32v
for third design, connect 2 and 3 and you have a 48v with center tap, so third design will get you about the same +32-34v
http://www.ebay.com/itm/MCF-B19624F-Transformer-100Va-2-X-24V-/130877003135?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e78e0957f100VA 2x12v or 1x24 with center tap. Exactly what you need, but enough VA for 2-3 identical amps
http://www.ebay.com/itm/CTFC100-12-Camdenboss-Transformer-100Va-2-X-12V-/360622945129?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item53f6cd7369As a sidenote, this guy simply buys these transformers from Farnell and adds his fees then sells on eBay.
Farnell doesn't ship directly to Greece, but they have a distributor in your country:
Darlas Electronic Applications SA
5, Kimonos Str
122 44, Egaleo
Athens
Greece
Tel: +30-210-59.86.179
Fax: +30-210-59.11.161
Email: darlas@darlas.gr
Web:
http://www.darlas.grThey have an online store in which you can see the prices, for example here's the link to 86 pages of transformers to choose from :
http://www.darlas.gr/comersus/store/comersus_listCategoriesAndProducts.asp?idCategory=17521983And if you search by product name, for example CTFC50-12 for the 2x12v 50VA transformer that matches your needs, you can find it at 20 euro on their site:
http://www.darlas.gr/comersus/store/comersus_viewItem.asp?idProduct=1890021You can go on farnell.com to the transformers category :
http://uk.farnell.com/isolationUse the filters there to select 2x12v, 2x15v, maybe even 2x10v (this should give you about +/-13v) , maybe also check 24v,30v,32v (they may have center tap but you only see if you check datasheet), maybe also check 2x18v if you may change your mind and do single power supply (third design)
select minimum VA rating 20va, maximum 100-150va, then look in the results and find something you like. Get the product code and enter it on darlas.gr site in the search box to see how much it costs for that store to get it for you.