Shark Buck

[LED Zeppelin]

Got my Shark Buck today, thanks Wayne.

Given the above external pot, once I remove the trim pot, do the three wires on the external pot need to go to particular solder points on the driver ?

thanks for the help.

dieselsmoke, hope you can follow this:

- Locate the three solder pads under the on-board trimpot. Viewing the Shark from the component side with the pads at lower right, you will see that the larger central wiper pad connects to the top soldering hole just to the right. There are two smaller pads under the large pad. The lower right pad connects to the lower right soldering hole, and the lower left pad does not connect to any hole.
- Connect the pads to the external pot. Viewing the pot with the shaft at top and the leads facing you, connect the large wiper pad (or top right hole) to the center pot lead, the lower right pad (or lower right hole) to the left lead, and the lower left pad to the right lead. I find it just as easy to solder to the pad as to the hole. The wires do not pass any current, so I use very thin flexible wire, 30 ga or so.

 

[dieselsmoke]

Very helpful, thank you LED Zeppelin !

After testing I find that my 3a shark buck only runs up to < 1a

I tested it with the original trim pot installed, just wired it up with 24g wire to an MC-E 4p using a 11.1v Li pack which is reading 12.4v. The pack cells are plenty capable to deliver 3a with PCB rated at 6.5a. I also checked the installed resistors and verified they are .10 and .05 ohm, so I think I have the right model shark buck.

You can see the current range I acheived below using the onboard trim pot at min and max levels. No power was applied to the board prior to being sinked to the copper C using paste and an aluminum bar.

One thing I did find odd, before I wired anything up I found there to be some electrical path between 3 of the four connectors and the copper C. I'm the farthest thing from an EE, and don't know if this is normal. All leads except the VIN showed electrical path to the copper C, albeit at extremely high resistance.

What should I check ?

 

[dat2zip]

Very helpful, thank you LED Zeppelin !

After testing I find that my 3a shark buck only runs up to < 1a

I tested it with the original trim pot installed, just wired it up with 24g wire to an MC-E 4p using a 11.1v Li pack which is reading 12.4v. The pack cells are plenty capable to deliver 3a with PCB rated at 6.5a. I also checked the installed resistors and verified they are .10 and .05 ohm, so I think I have the right model shark buck.

You can see the current range I acheived below using the onboard trim pot at min and max levels. No power was applied to the board prior to being sinked to the copper C using paste and an aluminum bar.

One thing I did find odd, before I wired anything up I found there to be some electrical path between 3 of the four connectors and the copper C. I'm the farthest thing from an EE, and don't know if this is normal. All leads except the VIN showed electrical path to the copper C, albeit at extremely high resistance.

What should I check ?

It appears the board is working as min LED current is very low and the fact that the pot is adjusting the LED current.

It appears if I had to guess is the Vf of the LED + DMM is near the input battery voltage and the board is not really in buck mode at the high end. It appears it is more in DD mode and that the 1A is actually the Vf at the applied battery voltage.

Is this possible that you have LEDs wired in series like 3 MCE?

If that is the case you can try two and see if you get the full range.

BTW: I like your test setup. Clamping to a metal strip or some simple heatsink is a great way to fire the board up. :thumbsup:

Wayne

 

[dieselsmoke]

Thanks for the quick reply Wayne.

The MC-E star I have is pre-wired as 4p, so to my understanding I should see Vf of between 3 and 4 volts, and my shark buck could offer each of the 4 dies up to 750ma each (I certainly could be wrong on this math.)

My intent is to use the board with a couple of serial wired P7's that I just received today, but that should be an equivalent setup as the 4p MC-E but with about double Vf. I can test a P7 tonight, and I'll check the Vf on the stars while I'm at it.

 

[dieselsmoke]

I got the P7's as expected and ran some tests with the board using 3 different battery packs.

7.4v - 2s 18650 Trustfire 2500mah, actual voltage = 7.68
11.1v - 3s3p 18650 Tenergy pack, actual voltage = 12.4
14.8v - 4s2p 18650 Tenergy pack, actual voltage = 15.46

The Tenergy packs have a PCB that kicks at 6.5a. I've never tested them that far but the 14.8v pack has run 32w of halogen which would be somewhere around 2a, and that worked well for about 2 hours. The protected Trustfire cells are fairly well known, and I can't imagine that any of these cells wouldn't be capable of 3a discharge.

As expected, the P7 behaved very similar to the MC-E 4p. I ran the emitters individual and also in serial. My end goal is to run two P7's in serial.

Results are below:

Battery--P7 Vf----P7 amp--MCE Vf--MCE amp---P7+MCE amp

7.4-------3.42v----2.18a----3.11v-----1.93a-------.75a
11.1------3.39v----1.05a-----3.10v------.96a-------1.9a
14.8------3.39v-----.84a-----3.09v------.77a-------1.48a

There seems to be a sweet spot at 7.4v with single emitter, or 11.1v with two emitters, but I'm still not getting close to 3a. Could this be a match of Vin and (Vf of emitters + board + DMM) providing the sweet spot ? I thought the buck board should even this out and provide constant current.

I know the 11.1 and 14.8v packs are further from full charge than the Trustfire cells, but I think both have enough charge to do better than this. I'm topping off the 14.8v pack today and will see if that changes anything.

So now I have data, but still no answer. Any ideas ??

 

[dat2zip]

dieselsmoke,

It's starting to sound like a bad board.

Most of the time either the board works or it doesn't work.

Is it possible the DMM measuring the current is on the input side and not the output side. Just need clarification on your setup.

Did you measure the Vf at the board or downstream closer to the LED. It's possible that the alligator clips, connections and junctions might be poor crimped or connected. There could be a substantial voltage drop across one or more connections and that could throw off the measurements you made and possibly explain the odd behaviour.

If all the connections are good I would say the board is defective.

Wayne

 

[dieselsmoke]

You got me on the right track Wayne. On your suggestion, I took a second look at my setup, and contrary to what I thought, I did have the DMM on the battery side of the board, hence the lower amp measurements using the higher voltage packs....

I soldered all the temporary connections together, and put the DMM in the right place between the board and emitters, and I'm seeing 2.755a with my external pot and any 7v or greater battery pack I use :twothumbs

Thanks for setting me straight !

 

[Aircraft800]

Is there a way to run two SHARK Buck 3A in parallel to push a single PhlatLight SST-50 LED to it's 5A maximum at 3.6V, even if it is for "Burst" only? I plan on running it in the 2.8A area most of the time, but a occasional 5A burst, and driven by 3 Li-Ion cells.

 

[petrev]

Hi

Update : I had a 1 level Shark-Remora but it wasn't Wayne's fault as I had damaged it while fitting it
Somehow knocked a resistor off apparently

Wayne sorted it out really quickly and didn't call me stupid once.

Cheers for the great service
Pete

 

[AaronM]

Does the Shark Buck run OK on one cell?
I want to run an SST-50 with 2amps or better on a single 18650.

 

[dat2zip]

Does the Shark Buck run OK on one cell?
I want to run an SST-50 with 2amps or better on a single 18650.

No, the Shark Buck needs a couple of volts overhead to maintain regulation. With a large LED or multiple parallel LEDs with Vf of 3.5V or so requires 5+ volts for the Shark Buck. That would be min or the voltage of the discharge state of the batteries and a fresh cell setup would therefore be 6-8V.

Wayne

 

[mudman cj]

Can I use a KD sku s006236 PWM board to act as a switch-controllable substitute for the Remora? I read on page 3 about using a 7135 chip as a PWM controller for the Shark, and this circuit I listed sounds like a similar approach without needing to modify the board, but I am not sure how to implement it.

 

[Aircraft800]

Can I use a KD sku s006236 PWM board to act as a switch-controllable substitute for the Remora? I read on page 3 about using a 7135 chip as a PWM controller for the Shark, and this circuit I listed sounds like a similar approach without needing to modify the board, but I am not sure how to implement it.

:thinking: KD sku s006236 is a Cat Eye Lens SKU: S006236
http://www.kaidomain.com/ProductDetails.aspx?ProductId=5701

 

[mudman cj]

I must be a bit lysdexic. That should have been s006326.

 

[cfive-1]

No, the Shark Buck needs a couple of volts overhead to maintain regulation. With a large LED or multiple parallel LEDs with Vf of 3.5V or so requires 5+ volts for the Shark Buck. That would be min or the voltage of the discharge state of the batteries and a fresh cell setup would therefore be 6-8V.

Wayne

Hi Wayne.For my first mod I like to use a Maglite 4D,a P7 -DSVNI emitter,a Shark Buck Driver and a Remora.Cells are 4 NiMh D size 12000mAh (input voltage 4.4V-5.6V).Like to run it at max.2.8Amps.
My dilema is min.input voltage.In post#24 you saying it is 3V recommended 4V and in post#131 min.6-8Volts.Please let me know which one is corect?
Thank you,regards cfive-1.

 

[dat2zip]

cfive-1,

Post 24 is the generic specifications.

For a specific application you must always have Vin greater than Vf or the Buck converter will not be stepping down. If the P7 Vf is 3.5V then Vin must always be greater than 3.5V for A buck converter.

The buck regulator will fall out of regulation when Vin approaches ~20% over Vf or ~1.3V above 3.5V.

For a 4 cell NiMH, Alkaline means you will maintain regulation for only a short period of time on high. After that it will fall into DD mode.

The batteries under load will sag making Vin lower on high.

Wayne

 

[mudman cj]

Edit: Nevermind my question about using a different board to control the Shark. I see now that it makes more sense to use the Remora. Not only is it cheaper, but it is also backed by MUCH better customer service.

 

[cfive-1]

cfive-1,

Post 24 is the generic specifications.

For a specific application you must always have Vin greater than Vf or the Buck converter will not be stepping down. If the P7 Vf is 3.5V then Vin must always be greater than 3.5V for A buck converter.

The buck regulator will fall out of regulation when Vin approaches ~20% over Vf or ~1.3V above 3.5V.

For a 4 cell NiMH, Alkaline means you will maintain regulation for only a short period of time on high. After that it will fall into DD mode.

The batteries under load will sag making Vin lower on high.

Wayne

Wayne thanks for help I hoppe you can give me more advice.
When Shark Buck goes to DD at ~4.8V will LED current rise over 2.8A and could demage LED (my batt.are high capacitty and high discharge current)?
Or may be you could sugest better driver for my aplication.
Thank you,regards cfive-1.

 

[mudman cj]

Hopefully no one will mind if I answer this one for Wayne.

The LED current will not exceed a 2.8 Amp regulation setting unless the batteries supply more than the upper voltage limit to the circuit (24V). When the battery voltage falls below about 4.8V, the LED current will no longer be held at 2.8 Amps, but will gradually decline from there.

 

[cfive-1]

Hopefully no one will mind if I answer this one for Wayne.

The LED current will not exceed a 2.8 Amp regulation setting unless the batteries supply more than the upper voltage limit to the circuit (24V). When the battery voltage falls below about 4.8V, the LED current will no longer be held at 2.8 Amps, but will gradually decline from there.

Hi mudman cj
Thank you for your replay(I think it's meant for me).I tested my batteries in DD input 4.1V output 2.3A at 3.5V at P7 LED.At input 5.4V(fully charged) output 7.5A(I stoped after few seconds).I did not test yet at 4.8V.
Regards cfive-1.