Modified DinoDirect Driver?

[Wolfman29]

Hey there everyone.

I got this driver (http://www.dealextreme.com/p/3-6v-9...rcuit-board-for-cree-and-ssc-leds-4-pack-3256) and it's pretty damn good. Unfortunately, I think I have encountered a bit of a problem with it.

You see, it runs normally at around 920mA. That's all fine and dandy, but I want to use this driver to run a 12x blu-ray, so I need to feed it between 450-500mA. So, I stuck some resistors on the positive output (my normal go-to modification so I don't have to do any SMD soldering) with a resistance equivalent to roughly 4.5 Ohms. Got the current to be about 450mA... until I kept it on longer.

The current gradually rose (a couple of mA every couple of seconds) until it got to 492mA and then I shut it off. But the problem is, I don't want to have it be a driver that increases current as on-time increases... that's dangerous.

I think the problem may be with the resistors I attached. They are normal, 1206 1/8W SMD resistors that I attached, but I put three 3.3 Ohm resistors in parallel (to give me 1.1 Ohms) in series with another three 10 Ohm resistors in parallel (to give me 3.333 Ohms) for a total of roughly 4.4-4.5 Ohms. However, I am thinking the reason it is increasing in current is because maybe these resistors can't handle the power I am feeding them? Or is there just a flaw in this method of modification?

Just so you know, I am using a 6x1N4001 and 10W 1 Ohm resistor for my test load.

Any answers? I don't want to end up killing a 12x 405... even though I don't even have it yet.

 

[lazeerer]

Search my Threads my Friend and you will find everything you are looking for..

 

[Wolfman29]

Alright. So I figure that you decreased the resistance on the R270 resistor and increased current, so I have to increase the resistance, yeah? Do you know the equation that may be used to find the current output...? I am looking to half the current, so maybe double the resistance?

 

[lazeerer]

Just fallow what did to mode this type of driver. But use your own value resistors.

Iam working on a custom driver based on something similar to this. Should be out soon.

 

[Wolfman29]

Yeah, found it >.< Sorry about that, thought it would be buried *within* a thread.

So how should I go about modding this then? I can't stack to increase current... should I just change out the R270 resistor with one that is like 1 Ohm or something like that? Maybe stack two 1 Ohm resistors? And what kind of wattage is required on these resistors, do you know?

 

[lazeerer]

You need to change the R270 Resistor to ~0.35ohm. You have to play around with it. a 1/2Watt Resistor is fine for that currant.

 

[bluuray]

View 5cSRWz.png on ScreenSnapr

 

[Wolfman29]

I feel very foolish right now. I always read the comment, too.

Anyway, now that I know how to correctly mod it, what was the problem with the incorrect mod that I did? Why was the current gradually rising?

EDIT:

Basically, I stuck higher value resistors on the output + lead to decrease current. Has worked in the past for me (drove a nice little 80mW PHR that way with a different driver).

Alright, so the equation for this driver is easy. But you have to know that R1 and R5 are run parallel. To find the output current, just divide 0.25V by the resistance in Ohms and you will get your output current in Amps (Ohms Law, anyone?). Anyway. So for a safe current of 450 or 475 mA for a 12x blu-ray, I need to use slightly more than .5 Ohms. I may just parallel two 1 Ohms and one 10 Ohm.

 

[lazeerer]

I have no idea what mod you did. Nore have i heard of modding any driver the way you did.

Sorry cant help there.

 

[lazeerer]

Also Please note this driver you have can only handle 1A. MAX..

Do not push it past that. It is using a different IC that is ratted for 1A. GO past that and you will 110% kill your diode when the IC Fails. The IC fails at 1.06A every time.

 

[Wolfman29]

I'm going to drive it lower than 1A Lower than .92A, too. Just gonna drive it at 450mA.

 

[Wolfman29]

Perfect! I must have done some bad soldering or screwed something up, because my calculated resistances necessary were wrong. However, I did end up getting exactly 500mA from my new modified driver! Works well now (was stuck for about an hour and a half because of a bad solder connection (had too much solder on the battery contact), was high resistance and led to about half of the current.... Anyway, it's all set now!

I love this driver! Works nicely and is very stable! Anyway, can't wait to get a 12x blu-ray!