Dx 12v 300mA driver modding help please!

[Paul Baldwin]

Hi,
a little while back I ordered a couple of these drivers. They are advertised on the DX site as 300mA. Reading the feedback it was apparent that they actually feed 700mA to the led which was what I wanted.
However, the latest ones I have do match the description and supply 300mA Infact I got 2 different driver designs in the same order.
The Dx site is down at the mo so I took a photo of the new and original drivers I have.

New Driver



Old driver





Is the resistor R15 in the top photo the one I have to change to alter the current and any ideas what sort of resistor I should replace it with to get roughly 700mA.
Sadly the original driver no longer works, it did until I started using a scalextric power supply that works at just under 16v, 12v was just fine though.
UPDATE. The sites up again now. I orderedhttp://www.dealextreme.com/details.dx/sku.13557 both times. From the discussion at the bottom of the page it looks like the chip used has changed to the PT4115 from the previous PT4110. I found a datasheet for it here www.micro-bridge.com/data/CRpowtech/PT4115E.pdf

Cheers

Paul.

 

[Paul Baldwin]

Can anyone help me out with this please? These drivers are usefull and cheap I've already made a 12v lead light for a friend and now another friend wants one but brighter would be better!
I'm capable of modding it but my maths isn't up to scratch

Thanks

Paul.

 

[linterno]

R15 means 0.15 ohms resistor. With that resistor and considering the formula found in the datasheet page 11:

Iout = 0.1 / Rs

Then you are getting 0.666 Amps or 666mA with that 0.15 ohms resistor.

You would need 0.1 / 0.35 = 0.285 Ohms resistor (get the closed one) to get 350 mA.

EDITED:

After re-reading I guess there is something wrong with that driver or with my interpretation since the stock resistor should give you roughly 700 mA.