Silly idea? Interchangable TC's

Zelandeth

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Silly idea? Interchangable TC\'s

Found myself pondering this this afternoon...

Some lights, I've noticed, there's a lot of space in the tailcap - relative to the size of a lot of the Luxeon drivers these days anyway.

In the world with this ever increasing demand for lights where you can change between output levels easily, a common solution seems to be to have several heads for one body, with a different driver for what is essentially the same LED.

Would it not be possible to set up a head with your LED of choice, and have the driver circuitry in the tailcap...therefore allowing you to have drivers set to whatever drive currents you wanted, switchable by a simple switch of tailcap. As the LED would be attatched in a more peremenent manner to the body, I figure a better thermal path could be designed in. Plus, the cost of just a driver and a tailcap would mean that the individual modules could be cheaper, as you're not having to buy an LED for every one of them.

Am I totally missing the point here? I am NOT a modder, just someone who got REALLY bored in the 23 hours we didn't have power yesterday, and thought this sounded interesting.

Most likely it's been done before if it's worth even thinking about though.
 

balrog

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Re: Silly idea? Interchangable TC\'s

It's not a bad idea at all. In fact, I think it's a great idea and I've thought about doing this myself before. The biggest difficulty in putting the convertor at the tail end of the light is the wiring. If you take the de facto standard in modular lights - the McLux PR - the only wires required are all neatly contained in the ecan and between the ecan and the LED. They are all short and easy to run.

If the convertor is in the tail, you may need one or two wires to run from the convertor down the length of the body to the LED. This is by no means impossible, but the process to manufacture and assemble the lights would have an additional complication. Machining a battery tube with a small channel or tunnel for these wires is possible but tricky, and certainly adds to the cost. There might be a small inefficiency introduced in the resistance due to the length of the wire(s), but I think this would be negligible.

You could do exactly as you have thought by leaving the convertor were it is at the head end of the battery tube and making this a separate detachable module to a head/reflector/convertor assembly. This is definitely doable. You just need some way of connecting the +ve and -ve LED leads between the convertor and the head when the head is attached to the body.

As it happens, McGizmo must have thought about this issue himself because his latest Aleph series of module lights use a "light engine" module which is separate to the head/reflector assembly. The light engine has both a convertor and LED attached and can fit in all three of the Aleph head sizes and all E series body sizes. With this system, rather than having one LED per head you have one LED per convertor. It's certainly a more modular and flexible approach to having the head, convertor and LED all as one module. The only drawback I see to this system is a potentially worsened heat path from the LED to the body, but I don't think this is significant.

Your idea favours the person that wants different brightnesses and/or battery combinations and typically uses the same head/reflector assembly in each such combination. McGizmo's system favours the person that has a preferred brightness/battery combination and likes to have different head/reflector assemblies for different tasks. Both of these systems require less LEDs on the whole, and that is a good thing.

I reckon that the ultimate system would be to have one module for the head/reflector, one module for the LED, one module for the convertor, then the body and tailcap as per normal. As long as you only used one light at a time, you'd only ever need to get a hold of one really sweet binned Luxeon III and Luxeon V for all your lighting needs /ubbthreads/images/graemlins/cool.gif
 

Zelandeth

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Re: Silly idea? Interchangable TC\'s

Good point. There's me not thinking about how the convertors work - totally forgot that the -ve line isn't battery ground. Oops! *bangs head on desk*

And as I said before, if it's a good idea (coming from me), it's most likely been done before by someone far better at thinking outside the box. And it looks like the general idea has indeed been done.
 

gadget_lover

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Re: Silly idea? Interchangable TC\'s

While I like the idea, it would be even better if we could come up with design that provides seperate LED holder, Converter holder and battery tube while still being space efficient.

I can exchange the DORCY 1AA body with a 4 LED head, or with a Luxeon modded head or with a 3 LED head. This is possible because the converter is at the end of the battery tube and a spring contact is used to connect to the head (with LED) to the body.

Hmmmmmm

Daniel
 

balrog

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Re: Silly idea? Interchangable TC\'s

Zelandeth, sometimes the -ve on the LED is connected to the -ve of the battery in which case you need a minimum of just one wire from the convertor to the +ve of the LED. Similar situation if the convertor +ve is connected to the battery +ve. Some convertors both -ve and +ve of the LED are not shorted to either battery -ve or +ve and a minimum of two wires will be required to connect from the convertor to the LED. It's by no means impossible to run wires from the tail to the head. I'm sure more than one person has made a regulated light this way.

gadget_lover, I reckon you've hit the nail on the head. Space efficiency is going to be a problem. Each additional spring can take up at least an extra few mms. And then there are resistive losses. How high is the resistance between each spring and its contact. Probably not high, but something to consider. It would be nice to see what the contact between the convertor and LED in the DORCY 1AA looks like - I've never seen one myself. It's going to be easier with the likes of a Badboy where the LED and battery -ve are common. For a Downboy it gets a little more tricky.
 

Hallis

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Re: Silly idea? Interchangable TC\'s

why not just have the driver circutry as part of the removable headpiece? Since you need different electronics for different bulbs and LED's and such.
 

gadget_lover

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Re: Silly idea? Interchangable TC\'s

The advantage to having a constant current driver in the body or tailcap is that it allows easier LED changes with less redundancy. Swapping the LED that's wired to a converter is a hassle.


Daniel
 
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