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Thread: Shark Buck

  1. #91
    Flashaholic* Techjunkie's Avatar
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    Default Re: Shark Buck

    Wayne,

    Thanks for the well worded reply. I'm considering a modified version of what I've described, and if you don't mind, I'd like to bounce the ideas off of you.

    Instead of running 5x MC-E, I'm considering running 4x MC-E and 1x XR-E (The reason being that the 5 small reflectors used here do a poor job of focusing the MC-E. I'm thinking that swapping out one MC-E and replacing it with one XR-E might allow me to fill the MC-E donut with the XR-E hotspot.)

    The power supply is still 8x LiFePO4 14500 batteries (which I'm considering charging in the modamag carrier with a 7s LiFePO4 pack charger to keep maximum voltage at or below 24v), and the Shark buck 3A is still the driver of choice.

    My dilemma is how best to drive the one XR-E at the same time as the 4P4S MC-E. Off the top of my head, I've come up with:

    a) run the XR-E in parallel with the 4P4S string of MC-E off of the Shark Buck 3A's output, using a lesser buck driver to bring the ~14.4v out of the Shark down to the 3.6V in requirement of the XR-E. This would steal some of that 3A output from the MC-E emitter's, but less than 350mA, if I'm correct, driving them at still more than 2650mA.

    b) run a separate buck driver just for the XR-E, powered in parallel with the Shark Buck 3A directly from the 16-24V power supply. I'm not so interested in modes or dimming, but if I were, I think I'd be tempted to use a Shark buck 1A for the XR-E and control both the 3A and the 1A with a single pot or Remora... Would that even be possible, or would they not appear to dim to the same levels?

    c) better ideas?


    Thanks!

  2. #92

    Default Re: Shark Buck

    You could use a high voltage buck driver for the single XRE LED. The SOB max voltage rating is 16V so that is not an option. I think there are other buck drivers that would suffice for non multi-level option.

    Option B is very doable with two Shark Bucks and one Remora to control both.

    Offhand I can't think of any option C.

    Wayne

  3. #93

    Default Re: Shark Buck

    Quote Originally Posted by dat2zip View Post
    I did some testing and I found the converter needs about 2V of headroom to stay in regulation. So, for this configuration a min of 5.5V is needed to run full power.

    I do not know why this is the case and I will look into more when I get a chance.

    Wayne
    Is this still the case, i.e., 2V of headroom needed? I have a current version 2A shark buck on the way, and will be driving 1-P7, ~3.5V Vf. Trying to make battery choice, and was planning on 1cell LiPo; no workie I figure? Would 2 cell LiPo, 7.4 V be too much for 1-P7?

    Thanks Wayne.
    totally enlightened!

  4. #94
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    Default Re: Shark Buck

    Wayne,

    I sent a PM about some problems I am having with a Shark Buck, if that isn't the best way to contact you please let me know! Thanks.

  5. #95
    Enlightened
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    Default Re: Shark Buck

    What is the voltage output for a shark buck with for (2 18650) 7.4 Volts input. I want to make sure the P7 I bin code I have will work properly. The manufacturer states the Vf is 3.25 to 3.5.

    Thanks
    Andrew

  6. #96

    Default Re: Shark Buck

    Quote Originally Posted by acgriff View Post
    What is the voltage output for a shark buck with for (2 18650) 7.4 Volts input. I want to make sure the P7 I bin code I have will work properly. The manufacturer states the Vf is 3.25 to 3.5.

    Thanks
    Andrew
    The Shark Buck limits current. The voltage output varies on every LED. You will be fine with 2 18650's and a single P7.

    Mac
    www.macscustoms.com
    *Note* Shipping Insurance must be requested.

  7. #97
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    Default Re: Shark Buck

    Wayne,

    I have a shark buck that seems to be malfunctioning. It has ~8V in and the Vf of the led is ~3.5V. I see no change in output when adjusting the pot over it's full range. The output remains constant and very very low. I do measure a difference in the resistance across the legs of the pot, but no change in output. Does this sounds like a faulty board or a wiring issue?

  8. #98

    Default Re: Shark Buck

    Hi Wayne,

    Do you have an update on this Remora issue with Shark Buck? I'm interested in getting a Shark Buck + Remora, but wanted to know what's going on with this, thanks!

    Quote Originally Posted by dat2zip View Post
    I did some simulations yesterday and discovered why the Remora doesn't PWM throttle to zero like it should.

    It is correctable and I believe some small modifications it can be fixed.

    The fix on the Shark and Blue Shark I will document soon. For the 10 Shark Bucks I have now they behave like the Shark does.

    The production Shark Bucks I will incorporate the filter network onto the board and it will make the modification easier.

    I need to see if the fix even works and I will test it and post on the results.

    Wayne

  9. #99

    Default Re: Shark Buck

    Quote Originally Posted by wildstar87 View Post
    Hi Wayne,

    Do you have an update on this Remora issue with Shark Buck? I'm interested in getting a Shark Buck + Remora, but wanted to know what's going on with this, thanks!
    Yes, the Remora design works exactly the same on the either Shark since the current implementation doesn't throttle low below 15% of full value. The three level values are ok with high being 95% of full output.

    There is no issues as is.

    If the Remora code was changed to lower the low then the implementation as is would not go below ~1/10 of full output and that is the way the Remora was implemented. You could use a different uP design and use the filter in the proper way to get full 0 to 100% control.

    I have used the Shark buck (adding the additional filter resistor) in an implementation on a Makita Dock prototype. The uP on the base board controlled two Shark Buck converter and I had full control over the output.

    The Remora board shape to to oddball and small to register properly with the programming fixture I have created or re-created and have not been able to re-program the Remora boards. The last hope is the use a dip clip from the top side to gain programming access and re-program the processor.

    Wayne

  10. #100

    Default Re: Shark Buck

    So if I'm understanding this correctly.. The Remora as is does not drive the Shark at 100% on high, but just 95% and the low is 85%? And for it to do this, it would have to be reprogrammed? I guess there is nothing I can do on my end, since I know very basic electronics, but most of what you said there went over my head.. I'm curious, could I use a D2Dim/D2Flex to throttle the Shark instead?

    Quote Originally Posted by dat2zip View Post
    Yes, the Remora design works exactly the same on the either Shark since the current implementation doesn't throttle low below 15% of full value. The three level values are ok with high being 95% of full output.

    There is no issues as is.

    If the Remora code was changed to lower the low then the implementation as is would not go below ~1/10 of full output and that is the way the Remora was implemented. You could use a different uP design and use the filter in the proper way to get full 0 to 100% control.

    I have used the Shark buck (adding the additional filter resistor) in an implementation on a Makita Dock prototype. The uP on the base board controlled two Shark Buck converter and I had full control over the output.

    The Remora board shape to to oddball and small to register properly with the programming fixture I have created or re-created and have not been able to re-program the Remora boards. The last hope is the use a dip clip from the top side to gain programming access and re-program the processor.

    Wayne
    Last edited by wildstar87; 05-22-2009 at 02:04 PM.

  11. #101

    Default Re: Shark Buck

    The Remora provides three distinct three levels. Low is 15% or so of full, medium is ~30% and high is near high.

    Depending on the components a board combination could give high close to 98%. It will vary slightly from unit to unit.

    I reference Full power as set by the sense resistor. The stock Blue Shark is configured for 1A full power. That puts low at around 150mA or so.

    Changing the sense resistor will set the full power output and the three levels will scale according.

    You can use fixed reistors and a rotary switch to give you more than 3 levels of brightness, a microprocessor board other than the Remora, an external potentiometor, on board potentiometer to control the brightness of the Shark boards.

    Wayne

  12. #102

    Default Re: Shark Buck

    Ah ok I'm understanding a bit better now. So if I wanted to run the full 3A output on a Shark Buck with a Remora, is there anything I can do to make that happen?

  13. #103
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    Default Re: Shark Buck

    Quote Originally Posted by thegeek View Post
    Wayne,

    I have a shark buck that seems to be malfunctioning. It has ~8V in and the Vf of the led is ~3.5V. I see no change in output when adjusting the pot over it's full range. The output remains constant and very very low. I do measure a difference in the resistance across the legs of the pot, but no change in output. Does this sounds like a faulty board or a wiring issue?
    Any suggestions on this?

  14. #104

    Default Re: Shark Buck

    Quote Originally Posted by wildstar87 View Post
    Ah ok I'm understanding a bit better now. So if I wanted to run the full 3A output on a Shark Buck with a Remora, is there anything I can do to make that happen?

    Yes, mount the Remora on the Shark Buck. High would then be very close to 3A. (98%).

    Wayne

  15. #105

    Default Re: Shark Buck

    Quote Originally Posted by thegeek View Post
    Any suggestions on this?
    If you think the board is defective send Cindy an email and we will send you a replacement. I would like to see the board to troubleshoot why it is not working.

    If you don't have our email you can send an enquiry through the shoppe web site.

    Wayne

  16. #106
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    Default Re: Shark Buck

    Quote Originally Posted by dat2zip View Post
    If you think the board is defective send Cindy an email and we will send you a replacement. I would like to see the board to troubleshoot why it is not working.

    If you don't have our email you can send an enquiry through the shoppe web site.

    Wayne
    Thanks, I'll send an email and then get this one in the mail to you.

  17. #107

    Default Re: Shark Buck

    We just discovered one of the resistors is in the wrong location from one log of Shark Bucks.

    Look at the converter so the trimpot is on your left and the inductor is on your right. The resistor in R3 is located above the trim pot on the left edge of the converter. This would cause no little or output.

    If the resistor is in R9, you are good to go.

    That resistor needs to be moved to R9. R9 is on the right of R3. If you cannot change it please send an email. We will have you send it back for re-work. PLEASE send an email FIRST to get an okay.

    Wayne has reworked all the remaining stock so the Shark Bucks which ship out starting yesterday are fine.

  18. #108

    Default Re: Shark Buck

    Hi there!
    I want to use a SHARK Buck 3A to drive one P7 at full power,powered by 2 liion cells.
    Does this setup run fine?And safe(aprox3A)?

    Thanks.

  19. #109
    Flashaholic* LED Zeppelin's Avatar
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    Default Re: Shark Buck

    Quote Originally Posted by Synergic View Post
    Hi there!
    I want to use a SHARK Buck 3A to drive one P7 at full power,powered by 2 liion cells.
    Does this setup run fine?And safe(aprox3A)?

    Thanks.
    Yes and yes, as long as your cells can supply the current, maybe up to 2A.

  20. #110

    Default Re: Shark Buck

    Just 2A?

  21. #111
    Flashaholic* Alan B's Avatar
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    Default Re: Shark Buck

    I would like to make a triple P7 or MCE powered by a pair of LiIon D cells. One way to do this is to use three shark bucks, one for each P7. Any issues with this approach?

    What is the standby current drain of the Shark?

    I would drive the PWM inputs from my own CPU. What is the PWM input frequency range?

    On the PWM input does zero equal off and 5 volts equal full on?

    Thanks,

  22. #112
    Flashaholic* Alan B's Avatar
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    Default Re: Shark Buck

    Quote Originally Posted by Synergic View Post
    Just 2A?
    Remember that this is a power conversion, 2A at 7V is 14 watts, which is about right to produce 4V at 3A plus converter losses. The converter makes current from voltage.

  23. #113

    Default Re: Shark Buck

    Quote Originally Posted by Alan B View Post
    I would like to make a triple P7 or MCE powered by a pair of LiIon D cells. One way to do this is to use three shark bucks, one for each P7. Any issues with this approach?

    What is the standby current drain of the Shark?

    I would drive the PWM inputs from my own CPU. What is the PWM input frequency range?

    On the PWM input does zero equal off and 5 volts equal full on?

    Thanks,
    There is a shutdown pin on the IC. It's hardwired to always be on. As such driving the control input to zero volts will yield a standby current around 5mA which is not that good. Driving the shutdown pin to GND will get the standby around 0.1mA.

    You need to filter the PWM. I believe I outlined the PWM control here in this thread or in the another shark thread.

    The control pin goes from off (0v) to full on (0.8V). The top end control gets nonlinear and you may need to goto slightly higher like 0.9V to achieve 100%.

    Wayne

  24. #114
    Enlightened
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    Default Re: Shark Buck

    MS_SS

    Just got my shark buck driver. When I first hooked everything up I was only getting 14ma at the battery. Thanks for your tip. I moved the resistor from r3 and soldered to r9. Everything seems to be fine now -1.8A. Although, working with a resistor smaller than a flea is not what I would commonly refer to as soldering.

    Thanks,
    Andrew

  25. #115

    Default Re: Shark Buck

    Will this work ok as an external pot for the Shark Buck 3a ?

    http://search.digikey.com/scripts/Dk...0C-001-203L-ND

  26. #116

    Default Re: Shark Buck

    Quote Originally Posted by dieselsmoke View Post
    Will this work ok as an external pot for the Shark Buck 3a ?

    http://search.digikey.com/scripts/Dk...0C-001-203L-ND

    Yes, that will work fine for an external pot.

    Wayne

  27. #117
    Flashaholic* Alan B's Avatar
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    Default Re: Shark Buck

    What's the input impedance of the control voltage input (with the pot removed)?

    Thanks,

  28. #118

    Default Re: Shark Buck

    It is a high Z input greater than 1MEG ohm.

    Wayne

  29. #119
    Flashaholic* petrev's Avatar
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    Default Re: Shark Buck

    Hi Wayne


    23.25V Open Circuit 6x17500

    21.1Vbatt under load
    1.8A to Shark Buck 3A
    driving 4x MC-E
    12.5V measured accross all 4 emitters driven (3.13V per emitter)

    Remora fitted (by you) but only 1 level ?

    Is this Max Level ?
    Seems a tad low ?
    (Guestimate: Pin = Iin*Vin = 21.1*1.8v = 37.98W
    (? Conversion Losses = 10%
    (Pout = 34.18W
    (Iout = 34.18/12.5 = 2.73A

    EDIT: Just measured actual current 2.8A

    Why only 1 level ?

    Cheers
    Pete
    Last edited by petrev; 06-22-2009 at 04:05 AM. Reason: Measured current 2.8A

  30. #120

    Default Re: Shark Buck

    Quote Originally Posted by dieselsmoke View Post
    Will this work ok as an external pot for the Shark Buck 3a ?

    http://search.digikey.com/scripts/Dk...0C-001-203L-ND

    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.

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