Shark Buck

[dat2zip]

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

 

[wildstar87]

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?

 

[thegeek]

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?

 

[dat2zip]

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

 

[dat2zip]

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

 

[thegeek]

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.

 

[Ms_SS]

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.

 

[Synergic]

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.

 

[LED Zeppelin]

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.

 

[Synergic]

Just 2A?

 

[Alan B]

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,

 

[Alan B]

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.

 

[dat2zip]

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

 

[acgriff]

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 :twothumbs -1.8A. Although, working with a resistor smaller than a flea is not what I would commonly refer to as soldering.

Thanks,
Andrew

 

[dieselsmoke]

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

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=3310C-001-203L-ND

 

[dat2zip]

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

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=3310C-001-203L-ND

Yes, that will work fine for an external pot.

Wayne

 

[Alan B]

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

Thanks,

 

[dat2zip]

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

Wayne

 

[petrev]

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

 

[dieselsmoke]

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

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=3310C-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.