17mm buck driver with >2.5A output?

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Slim Pickens
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17mm buck driver with >2.5A output?

Does this exist: a buck driver that fits in a P60 pill and pushes an XM-L close to (or over) 3 amps? Even 2A?

Flomotion
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Flomotion

PilotPTK
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Flomotion wrote:
Buck driver, 2.8a, 17mm.

http://www.lightmalls.com/amc7135-8-2800mah-1-mode-circuit-board-for-ssc...

That is not a buck driver. That driver is Linear.

PPtk

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Slim Pickens
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Thanks Flomotion, but yep that’s a linear current regulator. Useful for single lithium ion cell lights and provides good regulation used in conjunction with a low forward voltage emitter (like an XM-L). However, input voltage for linear regulators is quite limited because excess voltage is turned into heat. The amount of heat depending on the current the driver delivers. 8xAMC will draw roughly 3A, so if your cell voltage is 3.7V, and an XM-L’s forward voltage at 3A drive current is about 3.35V, the heat produced by the AMC chips equals 3A*(3.7-3.35) ≈ 1 watt.

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In my testing, the heat generated by the led vastly exceeds the heat from the chips. On separate sinks, the temp of the chips will stabilize when the temp of the LEDs is still climbing. Unless you are trying to burn off an excessive amount of over (>1V)voltage, a sink and host capable of maintaining <120C wont cause a problem for the chips. In other words, if your light over heats and shuts down it’s more likely the LEDs than the driver.

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texaspyro
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PilotPTK wrote:
That is not a buck driver. That driver is Linear.

Well, technically it is a buck driver. Just not a switch-mode buck driver.

Pulsar13
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texaspyro wrote:
PilotPTK wrote:
That is not a buck driver. That driver is Linear.

Well, technically it is a buck driver. Just not a switch-mode buck driver.

So true Smile it all depend on which “dictionary” we’re using.

Anyhow, think we (by we I mean texaspyro and pals) can design a schematic for BLF version “switching DC buck” driver? 3-8.4V, variable amps, parts from internationally available ebay/online sellers. That would be cool. 8)

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I take it that 17mm switched mode buck drivers capable of >1.8A output don’t exist in the wild?

allan d
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Slim Pickens wrote:
I take it that 17mm switched mode buck drivers capable of >1.8A output don’t exist in the wild?

I think you are right. I have been looking for them and so far have come up empty.

Allan

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BUMP

Any updates on this front? Why does this not exist yet? Sad

I absolutely MUST HAVE a 2x18650 (or even 2x16340? lol) MTG2 L2P! NOW!!!!1

Slim Pickens
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comfychair wrote:

BUMP

Any updates on this front? Why does this not exist yet? Sad

I absolutely MUST HAVE a 2×18650 (or even 2×16340? lol) MTG2 L2P! NOW!!!!1


I hate to say it but I’ve all but given up on 17mm switch-mode drivers, especially since the buck-boost driver at ShiningBeam went out of stock and the single cell “boost” driver fiasco at LightMalls…

2 amps can be safely achieved by resistor modding the 17mm AX2002-based buck driver at DX but it’s single mode only :/

I want my first MT-G2 project to be something slightly smaller than a C8, a la Convoy M1 or M2. The Convoy L1 would have been a perfect host (comes with the 2.8A LD-29 buck driver) but it’s been out of stock for a while Sad

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2x26650 C8-size head: http://www.cnqualitygoods.com/goods.php?id=1713

2x26650 smaller than C8 (takes the ~37mm reflectors with the threads around the OD at the front, and the OP one for the SST50 works good with the MTG2): http://www.cnqualitygoods.com/goods.php?id=1143

Too bad I don't have any of the fat cells, I really like the second one.

PilotPTK
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comfychair wrote:

2×26650 C8-size head: http://www.cnqualitygoods.com/goods.php?id=1713

2×26650 smaller than C8 (takes the ~37mm reflectors with the threads around the OD at the front, and the OP one for the SST50 works good with the MTG2): http://www.cnqualitygoods.com/goods.php?id=1143

Too bad I don’t have any of the fat cells, I really like the second one.

That second one is a piece of s**t, just for the record. Bought one. Opened it up. Threw it in the trash.

PPtk

I am currently extremely busy with work. Please do not expect a response from me quickly. I will be dropping in as time permits, but the amount of time I can dedicate to responding to topics and PMs is very limited.

comfychair
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Hrm. Bad machining/QC issues, or poor design? I can get pretty creative but some things just can't be fixed.

PilotPTK
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comfychair wrote:

Hrm. Bad machining/QC issues, or poor design? I can get pretty creative but some things just can’t be fixed.

All of the above. Things don’t even physically fit together correctly.

I am currently extremely busy with work. Please do not expect a response from me quickly. I will be dropping in as time permits, but the amount of time I can dedicate to responding to topics and PMs is very limited.

texaspyro
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PilotPTK wrote:
Things don’t even physically fit together correctly.

Everything fits anything with the help of a big enough hammer… J)