resistored led's

resistored led\'s

Question #1:
Say you wanted to direct drive a single led, but wanted to add in a resistor. Instead of soldering a resistor to the led, could you make up a "resistor sandwich" with just the resistor that could be dropped into the battery tube? That way, you could make up separate "resistor sandwiches" with different resistors.

Question #2:
Could you do the same thing when you want to use multiple led's. Instead of resistoring each individual led, could you make a single "resistor sandwich" that would work instead.

I have no application for this, just asking questions.

Re: resistored led\'s

A1:
i've been considering the exact same thought.. i've seen 'resistor discs' for exactly this purpose while browsing... there are a couple issues: is there space? are you going to loose it when you change batteries.

A2:
I think you are just saying if you have multiple LEDs in the head of the light.. taking a 'shortcut' and using one main resistor in the battery tube to protect them... this will work in principal but it's best to individually resistor LEDs in a network if they are parallel... it helps balance the current and brightness... if they are in series doesn't matter... either way works.

-awr

Re: resistored led\'s

Hi Andrew and thanks for your input,

Ok, here's another scenario. Instead of having different led sandwiches, like a BB500 or MM+ ....could you have a single led with different regulation sandwiches that you could drop down the battery tube?

Say you go camping and want long run time? Drop in your long run time regulation sandwich down the battery tube and away you go. Or say you want more light, less run time....different regulation sandwich. That way, you could have a very versatile light using one led and different "in the battery tube" regulation sandwiches. Most of my lights have some room in the battery tubes, at least the larger cell lights do. The smaller the light, the less room it seems. Guess we'd just have to be careful and not lose anything. /ubbthreads/images/graemlins/wink.gif

I have no idea how to even make the simplest of sandwiches. These were just concepts I have been thinking about.

Re: resistored led\'s

Anyone else?

Re: resistored led\'s

Sounds like a good idea to me, and could be done easily enough. You could just make resistor-sandwiches of various values to change the amount of current to the LED. Or, you could get fancier and make a little regulator sandwich, too. Maybe you could put two sandwiches in - a resistor one and a regulator one, so that you'd have all sorts of configurations to play with.

Re: resistored led\'s

Two problems with "in the tube" sandwiches.

1) The sandwich consumes power, so you need a way to interupt the power before it gets to the sandwich. This is easy if you use a tailcap switch. Harder if you do anything else.

2) The presure exerted on the battery by some tailcap springs can be pretty strong. You have to take that into account. You also have to account for the fact that adding 1/4 inch thick sandwich may cause too much pressure on another part, loke the switch.

3) The converters produce heat that has to be removed somehow.

Ok. That's three. Oh well!

Daniel

Re: resistored led\'s

Thanks Daniel,

That's all I wanted to know. Sounds like too many issues.

Re: resistored led\'s

another thought about the down-the-tube sandwich idea... some designs need the LED cathode to return to the sandwich (not common ground) that would make it impossible to solve... but anything's fair in love and flashlight war... the peak aaa mod i just did was appaerntly pretty original... 3 way switch with just twisting the head... the 'infinitely variable' model is coming next.. keep thinking like you are and you'll come up with something pretty cool. ... and share with cpf so we can cheer you on.

-awr