mlehmanThere is even better stuff out there, if you're willing to search it out and pay a little more. For example, there's some really good 36 gauge flexy stuff I've heard of, but not tried yet
Mike, thanks for the tip. I'll have to keep an eye out for it.
Ken
Most HO and N decoders use 30ga wire. Haven't burned one yet except with an errant soldering iron.
kenkal Thanks for the comments Mike. FYI, I have been using the wires from computer disk drive flat cables, they are 40 conductor and 28 gauge wire. Very flexible wire when stripped off the cable to a single wire. Ken
Thanks for the comments Mike. FYI, I have been using the wires from computer disk drive flat cables, they are 40 conductor and 28 gauge wire. Very flexible wire when stripped off the cable to a single wire.
Ken,
Yep, that's another option. For internal wiring, works great.
Because things are relatively lighter with most HOn3 locos, I always try to use the most flexible wire I can get between the loco and tender. Mouse wire is typically 30 gauge, sometimes thinner. It also has a very higher wire strand count and an extra flexible insulation. So if you need something that's even more flexible than the flat cable wires, the mouse wire works well.
There is even better stuff out there, if you're willing to search it out and pay a little more. For example, there's some really good 36 gauge flexy stuff I've heard of, but not tried yet.
Mike Lehman
Urbana, IL
Good comments Randy. I'm finding that LEDs are using less and less current these days. Not that many years ago we were happy to get the brilliance need with 20ma. Today, I have many that are really bright at 5ma and some even at 2ma. For that reason, I don't use a standard or default resistor installation but try each LED in a LED tester to determine the rough target ma for the brilliance I like and use an accordingly matched resistor.
As for magnet wires, I have a roll of 26 gauge, but I picked up some 38 gauge red and green rolls from All Electronics this past week and plan to use them in signals.
Interesting chart, GREGC. Thank you. Ken
Yeah, most don't list anything for the smaller wires.
Thanks for commenting, Betamax. Ken
For an LED, that should probably be resistored to less than 2ma, the fine magnet wire works fine with no measureablke power loss. In some cases, like a signal head, it's almost impossible to use anything but that sort of wire, there's only so much speace inside a scale diameter signal mast to fit the wires. In a loco, it can be an issue with lots of lights, or lights in confined spaces like ditch lights. The magnet wire is fine enough to allow the wires to fit without interfering with putting the shell on.
The voltage drop is neglibile in such cases - despite a relatively high resistance per foot for the fine wire, first of all there is usually much less thna a foot of it, secondly the voltage drop depends on the current flow, and if you are talking about white LEDs with a 1K resistor, that's less than 10ma - and sometimes still too bright - I've seen 2.2K resistors used, that results in less than 5ma. Wire that is too thin to handle even those low currents is too small to be worked with normal hobbyist tools - the bonding wires from the actual chip to the external pin in DIP style chips is too small to even see without magnification yet can handle more current. Or hold a clear cased 3 or 5mm LED up to the light and look for the tiny bonding wire from the anode leg to the semiconductor junction sitting on top of the cathode lead. That finer than a hair wire can handle the full LED current.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
This wire chart covers smaller gauge wires: http://www.cirris.com/testing/resistance/wire.html
as the above chart shows, the small the wire the greater resistance. While I'm sure there's a limit to how hot a piece of wire can get before it melts, the voltage drop across the wire would probably cause problems much sooner.
The wires between a decoder and motor are pretty small, but they are short. There would be a larger voltage drop if you used the same gauge wire over several feet.
According to the chart, 30g wire has 0.1 ohm resistance per foot. So there would be 4mV dropped across 1 ft of wire (20 ma * 0.1 ohm/ft * 2ft (remember there is 1 ft in each direction). How much of a voltage drop is acceptable?
another way to look at it is you might use a 180 ohm resistor to limit the current 20ma through a 1.4V LED using a 5V supply. 2 ft of wire resistance is 0.2 ohm. How does 0.2 ohm compare to the 180 ohm resistor?
greg - Philadelphia & Reading / Reading
The word you are looking for is ampacity. There are charts out there listing that, but they may not included light gauge wires.
For small currents, light gauge wire is OK, and due to the lengths used, ampacity and voltage drop are not really an issue.
Found this:http://www.hagemeyerna.com/getdoc/93f497f0-29a2-4a84-bd81-8e529103ced1/Wire--basics-of-Ampacity-or-Copper-Wire-Current-Ca.aspx
Hope that helps.
I have used surface mount LED's and they came with #36 wire attached.
My experience and from what I've heard, you can use as tiny as you can find. In the short lengths and low amperage found with DCC and modern motors, it's basically impossible to run into an issue of too small gauge wire in HO and smaller scales. Bigger scales I can't say for sure. There is never going to be an issue with big enough for a LED, as they all are unless you're talking about one big enough model railroaders don't use them.
There are two exceptions. The power leads from the decoder to the motor probably take the highest current (unless you only have one set of wipers, anyway) so going with a larger gauge could be good and it's usually all inside and out of sight anyway. The other exception might be a loco with a high draw motor like an open-frame. In that case, beef up all the wiper wires, too.
Also, the more wipers you have, the smaller the gauge on their leads needs to be. The amp load is distributed through many points, rather than a few.
BTW, a narrowgauge colleague from Australia, Laurie McLean, taught me a cheap, handy source of fine, flexible wire can be found by slicing open the cords of computer mice. It doesn't even matter if the mouse still works or not, but better ask your wife or office mate before taking theirs...
Does anyone have a chart of the current capacities of small wires, perhaps 26 to 40 gauge? Sometimes in wiring in decoders or even track signal units it would help to use smaller wires for the LEDs, for one reason.
I have looked all over the internet and found AWG for larger gauges (but with different capacities for some reason) , NEC for some gauges, a table at http://www.powerstream.com/Wire_Size.htm which seems to specify chassis currents, which is likely what I want, but I'm not sure. So many internet sites, especially those at ask.com are nothing but pointers to items for sale and look doubtful that there really is a table to look at. I tried looking at various forums including this one.
If not, then does anyone know the smallest wire to use for an HO loco in DCC or the smallest wire for a 10 - 20ma LED?
Certainly this is not a critical issue, but more for just curiosity as I've used 28 and 30 gauge for both loco and LEDs with no seeming ill effects. But can I go smaller?
Thanks for any info you can offer. Ken