If you have or can get hold of a suitable low voltage (under 30V) power supply (AC or DC) and don't need remote radio control one of these may be worth considering.
Fairly typical with modern electronics, you can buy the complete thing from China cheaper than buying the components in the U.K. I reckon that heat sink as a one off over here would probably cost as much as the whole thing from China!
You'd need to replace the adjustment potentiometer with a volume control type mounted on some form of box for convenient operation together with a DPDT switch to reverse direction. A suitable quick blow fuse on the output would also be a good idea, the electronics limit the current to 5A but don't switch it off, they just pass 5A through the fault until you turn it off.
http://www.ebay.co.uk/itm/LM338K-DC..._Measurement_Equipment_ET&hash=item2562f260f8 < Link To http://www.ebay.co.uk/itm...mp;hash=item2562f260f8
Fairly typical with modern electronics, you can buy the complete thing from China cheaper than buying the components in the U.K. I reckon that heat sink as a one off over here would probably cost as much as the whole thing from China!
You'd need to replace the adjustment potentiometer with a volume control type mounted on some form of box for convenient operation together with a DPDT switch to reverse direction. A suitable quick blow fuse on the output would also be a good idea, the electronics limit the current to 5A but don't switch it off, they just pass 5A through the fault until you turn it off.
http://www.ebay.co.uk/itm/LM338K-DC..._Measurement_Equipment_ET&hash=item2562f260f8 < Link To http://www.ebay.co.uk/itm...mp;hash=item2562f260f8