The "FETtie" - 500W Tailcap Switch for Z41 / FM26XXX

VanIsleDSM

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Introducing the ultimate high power tailcap switch for Z41 and FM26XXX hosts.

Designed as a suppliment to the 1450 Lumen P60 Quad drop-in. This switch's capabilities extend well beyond it's originally intended necessity.

The P60 Quad thread is quite longwinded now, so I wanted to make a separate information thread for the FETtie for any questions or comments.

With any Linearly regulated or Direct Drive light, this will give you more current, and more lumens.

With any Buck, Boost, or Buck-Boost regulators, this will reclaim power currently being eaten by your higher resistance switch, and provide longer runtimes.

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How does it work?

The FETtie uses a solid state semiconductor, a MOSFET. Essentially a relay, with no moving parts, which is turned on by the clicky switch. The Clicky switch itself only conducts 100 nanoamps, that's 0.0000001A, to activate the semiconductor. This means the clicking mechanism will last nearly forever, as the electrodes will not wear from arcing.

The FETtie uses a small coin battery, 1216 size. You do not need to worry about this battery becoming depleated however. It's like the battery in a watch, it will last for many years. Even being left on, the switch will draw less current from the coin cell than it's self discharge rate


Specifications:

Current - 25A+

Voltage - 12V MAX

0.0034 ohm Rds(on) MOSFET resistance

Beryllium copper spring, Pure silver plated for extra conductivity, 24K gold plated contact area.

Gold plated contacts from the FETtie to host.

Threaded brass body

Panasonic 1216 coin cell included



Here are some graphs comparing it's performance to a McClicky switch with various cells using my 4.2A Quad drop-in. These results would be compounded with higher currents.

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I'll update with some pictures soon. These are only available to those on the closed P60 Quad drop-in waiting list at the moment, but they will be available for all shortly.
 
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Linger

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+1, charts look great.
I'd be in the waitlist for one tailcap switch but you said there' isn't a list. So I'll just wait :) And say it sounds good. Please update with pics when able.
 

Hack On Wheels

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Yes. That's the drop-in. What is the driver in the drop-in?

I'm going to venture a guess that it is a linear regulator based driver, with 12 chips to give the 4.2A. I can't do any better than a guess though.

This idea sounds great; I wonder what FET is being used in it? 500W capability is pretty serious business.
 

CKOD

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I'm going to venture a guess that it is a linear regulator based driver, with 12 chips to give the 4.2A. I can't do any better than a guess though.

This idea sounds great; I wonder what FET is being used in it? 500W capability is pretty serious business.


You think thats impressive, look at what the boys at STmicro have
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-7614-1-ND

Thats an insanely small package (9mm x 14mm) for carrying triple digit currents, but looking at the charts, it needs at least 5v to to reach a nice low resistance, and 10v to get its .001 ohm spec. For single short (.1 mS) pulses they spec over 1000 A in the "safe operating area" think thats enough to instaflash some hotwires? :grin2:


Either way, not bagging on the FETtie, just pointing out that there are some pretty crazy semiconductors out there if you have the $$ for them (though $6 is surprisingly low for the above FET)
 

VanIsleDSM

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The FET above is over 1/2" x 1/2" fitting it into a circlular area. If You could fit that into a Z41 switch with 10V, or even 5V of battery then my hat is off! ..and I would like to borrow your shrink ray for some of my currently inconceivable projects.

Full current rating of the FET in the FETtie is 80A, I derate to 25A for safety sake.

Go nuts if you want, but pay attention to the heat in your tailcap. The FET is sinked through the brass threading into the tailcap, so if you're going for serious amperage, maybe put some thermal grease on the threads.

If anyone needs triple digit amperage, just ask me. I'm sure however, that the FETtie will cover most all needs. I'd be really interested to make a "super FETtie" if there was a need for one though.

It's a low drop-out linear driver with 4 separate outputs. One for each LED. It's for use with a single cell. Mode configurable, low battery warning, thermally protected.

The graphs stop at 1.84A, a figure corresponding to 750 lumens, or half brightness of the drop-in.
 
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CKOD

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The FET above is 1/2" x 1/2" If You could fit that into a Z41 switch with 10V of battery then my hat is off! ..and I would like to borrow your shrink ray for some of my currently inconceivable projects.

Full current rating of the FET in the FETtie is 80A, I derate to 25A for safety sake.
I figured it was derated, as bad things tend to happen when you run transistors at their nameplate current and voltage ratings without consideration. I'll save the 280A beast above for if I ever make a 2kW + light (20x CSM-360 showerhead? yes please :crackup: )

Impressive results in the increase in regulated run time in your graphs, any idea how much of a resistance drop it is vs the McClicky?
 
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donn_

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I can vouch for how well this switch works with the 4x XP-G drop-in, which measures 5.6A at the tail on a 26650 cell. It's a pleasure to use.

Here's the host:

IMGP3437.jpg


A ribbed M2 bezel on an FM 1x26650 tube/tail with the FETtie in the tail. It took some time to get used to the reverse clicky, and I still miss momentary, but once accustomed, I was right at home with it.

I tried the same bezel/drop-in on a BigLeef setup, which has a 10A rated tailcap (Judco, IIRC), and the difference in brightness was notable. The FETtie is much brighter.

I plan to test the switch with some incan hotwires soon.
 

flashfiend

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As a nighttime jogging light when I need to change brightness with the light still on I think I am going to appreciate it being a reverse clicky. I think forward clickies are more for those times when you want momentary so you don't give up your position in certain situations. I've still got my McClicky for those. Now I just have to receive my FETties so I can make the comparison myself. :)
 

VanIsleDSM

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They do each have their advantages, and people have different preferences for different applications.

I would like to offer a forward clicky version, and I'll be looking into it.
 

FroggyTaco

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They do each have their advantages, and people have different preferences for different applications.

I would like to offer a forward clicky version, and I'll be looking into it.

Very cool..I want to have a 7-9 neutral XP-G light in a cut down Mag C with a tail switch driven by 2-26500 IMR's & a McClicky will be the weak link in the config due to current draw if my calcs are correct.
 
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