Modifiying Blue Shark for higher output?

[gav6280]

Can the sandwiche shops blue shark boost converter board be modified so that its constant current output is approximately 1200ma?

 

[Greg G]

Can the sandwiche shops blue shark boost converter board be modified so that its constant current output is approximately 1200ma?

I have done it to a green Shark, so I assume yes.

I forgot what the value was on the extra sense resistor, but I piggybacked it on top of the existing one. It was something like a .27 *I think*. The resistor calculator on the Shoppe will probably help you with that. I think there is also some more info about it on the original Shark thread.

Good luck.

Edit. I found one of my old posts where I put a .27 resistor on top of the .1 that is already there. It was a quad Cree light and the voltage to the LED's went from 14.8 to 15 volts even. I don't know how much current that equated to. I didn't pull the wires off and hook it up to my power supply to get a reading.

 

[Al Combs]

Can the sandwiche shops blue shark boost converter board be modified so that its constant current output is approximately 1200ma?

If it's a question of what value resistor you need, a 0.083 ohm resistor will give 1,200ma output. Wayne give a few examples on the Blue Shark page in the Shoppe. The correlation between the current and the resistance is to take the reciprocal of either value and divide that answer by 10. That will give you the corresponding other value. Current is not ma. here but amps. If you need to stack resistors to achive 1,200 ma., then you need to add a 0.5 ohm on top of the existing 0.1 ohm resistor. That's 1/R1 + 1/R2 ... +1/Rn = 1/RT. In Greg G's example a 0.27 ohm resistor in parallel with the Shark's 0.1 ohm resistor should create an RT of ≈ 0.073 ohms or ≈ 1,370 ma. output.

If it's a question of will 1,200 ma output blow the Blue Shark, you'd really have to ask Wayne about that. There is however a CPF Q&A about the green or older Shark where he describes how to change the output to 2 amps. As Greg G said, 1,200 ma. certainly seems doable. Post number 26 in that same thread says the Green Shark's IC was rated for 3 amps max input and he recommends 2 amps max. If you had a multi-emitter light that you are driving hard, the idea is to get the battery voltage as close to the LED's requirement without going over. The will keep the input current as low as possible and more importantly the heat the Shark generates. The trade off will be a higher battery voltage means you can't use the dimming feature of the Shark.

 

[gav6280]

So if i soldered on a 0.27 ohm resistor on top of the one all ready on the board i would get almost 1400ma?

How many watts should it be rated for?

Would this do it? http://uk.farnell.com/vishay-sfernice/rwm-4x10-0r27-5-tr1000-e1/resistor-ww-3w-5-0r27/dp/1109196

or more like this sort of thing:
http://uk.farnell.com/koa/sr732ettdr270f/resistor-0r27-1-1210-0-5w/dp/1399804?_requestid=171544

 

[Al Combs]

I was basically giving a math answer. Wayne is the Shark expert. I don't know the max power rating of the Blue Shark. The Shark Q&A I pointed to seemed to indicate current and heat being the limiting factors. Although at 1,370 ma I'd be more worried about the LED's than the Shark. If it's going in a dive light, I think you can get some excellent cooling by just gluing the Shark to the case wall with Arctic Alumina. If you need a more specific answer than that, Wayne has a forum on CPF for the Shoppe and can answer specific questions about the Blue Shark.

As far as the SMT resistors, your second link is the right type but the wrong size. Post 9 of the Q&A I linked to mentions the SMT sense resistor package used in the Shark are 0402's. They are extremely small and measure only 1 by 0.5mm. The 1210 package would be way too big to piggyback on top of a 0402 resistor. If you do a product search on Farnell for fixed resistors, they have a parameter field called "case style". Select 0402 and that will reduce the selection list to only the size used on the Shark.

Good Luck

 

[gav6280]

Is there a CPF member i could send it to, to get the soldering done as my eyes and hands are not going to be able to do this very well...

 

[Al Combs]

Have you tried asking Wayne a.k.a. dat2zip? He sells the regular Shark with a pot removal option for $3 more. Perhaps if you send him a PM and explain your experiment / assumption of responsibility and just ask him to do it for you. He can both answer the specifics of the likelihood of success and hopefully for a meager fee...

 

[gav6280]

Yep already did that, but just wanted a second option in case he is to busy...

 

[Greg G]

Just do what Al said and piggyback a .5 on top of the .1.

I installed a new Blue Shark the other day into my penta Cree Q5 M@g with the .27 added. Yup, could tell a difference. I'm not telling you it's safe though. I have extra boards and led's on stock in case I burn out parts. So far so good though. I did it in the name of science. They are mounted on an excellent heatsink. That helps.:naughty:

 

[gav6280]

Ok i thin i have now found the correct ones : http://www.rapidonline.com/Electron...SMD-Resistors/0402-1-Chip-resistors/73103/kw/

So up until now i have used my 40 watt traditional soldering iron and normal hardware store electronics solder and flux.

But i have just herd about this mythical stuff, solder paste?

What is it? How do i use it? Where do i get in in the UK?

GregG how did you do it? It's just so small...

 

[Greg G]

It will try your patience.

I tin both ends of the resistor first, then set it on top of the existing .1ohm resistor, holding it down with a small tool, like a tiny screwdriver. Then I set the heat on the iron(I have an adjustable model) so that I can apply a small drop of older to a sharp tip without the solder burning up, and then touch the tip to one end of the resistor pair until the solder flows together between the two. The other end is easier because you don't have to hold the new resistor in place.

Good luck with it.

 

[Al Combs]

Ok i thin i have now found the correct ones : http://www.rapidonline.com/Electron...SMD-Resistors/0402-1-Chip-resistors/73103/kw/

So up until now i have used my 40 watt traditional soldering iron and normal hardware store electronics solder and flux.

But i have just herd about this mythical stuff, solder paste?

What is it? How do i use it? Where do i get in in the UK?

GregG how did you do it? It's just so small...

That's a 402 package alright. But this is from a different site that has a minimum order of a 100 pieces. That seems like a bit much.

Paste is pretty cool stuff. The electronics guy at work uses it for SMT IC's. You know those IC's whose legs are so close together you wonder how the heck do they solder all those little feet with no shorts. His soldering station has a tool on it that's for lack of a better way to describe it is a 1mm wide nozzle, high temperature hairdryer. So you smear the paste (ground up solder plus flux) all over the board and it balls up when you hit it with the hairdryer. Apparently solder actually has properties of surface tension when ground up to small enough particles. They also use paste when they stick a whole board or something like an LED star into a reflow oven. The weird thing is it goes bad after a while. He told me if it's more than a half year old it will get a few shorts on every IC he does. Don't know where to buy it. There's always Google. The guy I know at work gets it from the parent company in Germany.

The thing that might help you here is you need three hands for this kind of work. For small work with a regular soldering gun, I wrap a paper clip around the tip. You have to do it when it's hot with pliers so it won't wiggle around when you're finished. Then put some regular solder on the coils of the paper clip to get good thermal transfer. Cut it off so it's about 8mm long and you've got a workable mini gun, for solder not bullets. You need a jewelers screwdriver to hold the 0402 against the existing one and the other hand is holding the soldering gun. Which means you've got the spool of solder in your mouth. Paste would definitely be a help on this kind of job.

BTW, did you know the Shoppe sells 0603 SMT resistors? They are a little bit bigger at 1.6mm long. Which is probably close enough that you have enough overlap on the end caps if you line it up properly. Well if you can't find another source in the UK.

 

[gav6280]

Thanks for all your input i am going to give it a go...

Even 100 pieces is so cheap, that it's ok.