using Ngineering 38AWG wire

[Deleted]

I am getting ready to install sound in a Kato N-Scale SD40-2. I have a plan on where to put everything, but have a question for the ele tronics experts.

I am going to use a Loksound Select Micro. I want to cut the wires off and replace them with the Ngineering 38awg wire. My plan would be to take four strands and twist them together. Basically use four strans of wire per per decoder pad. 

My question is. Would that be enough wire to handle the current needed to operate the decoder?

I know it is enough to handle the LED's. But what about the current from the track to the decoder and then the decoder to the motor. Also, how about from the decoder to the speaker?

My reason for asking is that using 38 gauge wire will make routing the wire very easy. The wire that comes with the decoder can be a little thick for routing around a frame in N-Scale.

[Mark R.]

Doubling the diameter of a single wire is the same as decreasing the gauge number by 6. So, two 38 gauge wires twisted together would be the same as a 32 gauge wire. Twist two of those together (4 38 gauge wires) would be the equivalent to a 26 gauge wire .... the trouble is, the wires are all insulated. So, in reality, you are still passing all the current through four single 38 gauge wires. You really aren't gaining any capacity by using multiple wires.

According to this chart ....

www.interfacebus.com/Copper_Wire_AWG_SIze.html

.... 38 gauge wire is only rated for .022 amps (22 milli-amps) - hardly adequate for motor / truck leads.

What I've done when there's a huge chunk of weight in my way, is use my Dremel with a small bit and cut grooves in the weights where I need to run the wires. A few dabs of CA hold them tight in the grooves where they belong.

Mark.

[lyled1117]

Mark, actually the equivalent wire gauge of the four conductors in parallel is smaller than what you explain. Two conductors of the same size (gauge) only change by very close to three for the equivalent wire gauge. Two #38's would be the rough equivalent of a single #35. Then, two #35's (4 - #38s) would then be the the rough equivalent of a #32 wire. The chart provided by you proves this. The circular mil size (an approximation of cross sectional area) for #38 wire is 15.7 c-mils . Two times that is 31.4 which is nearly equal to the value for #35. Four times 15.7 (or two times 31.4) is 62.8 which is a small tad less area than a #32 wire. That is still a little smaller than the #30 gauge provided on many decoders, but it is close enough to consider if you know the motor is an efficient one like many motors are presently. To get to #30 gauge, six #38's would be just slight bit under that size and would certainly carry one amp safely.

Lyle

[Mark R.]

Lyle, guess maybe my information was a case of "don't believe everything you read on the internet " ?

The fact that each wire is enamelled and insulated from each other makes no difference in the equasion ?

I dunno - it just doesn't feel like a good idea to me. I've seen regular insulated wire get pinched and worn to the point of shorting. This combination just seems like an invitation to potential trouble.

Mark.

[lyled1117]

Dec 30, 2013 10:18:36 GMT -5 Mark R. said:

"The fact that each wire is enamelled and insulated from each other makes no difference in the equasion ? "

No. Insulation, etc, would be a factor for the mechanical size of course, but it doesn't alter the conductor size which is the ultimate concern. At the current levels and the frequencies we're using we can look at the parallel wires as parallel equal value resistors where the current will split pretty evenly over whatever paths it finds.


"I dunno - it just doesn't feel like a good idea to me. I've seen regular insulated wire get pinched and worn to the point of shorting. This combination just seems like an invitation to potential trouble."

Like many other things, there are trade offs. If there is movement and rubbing on the wire, there is risk of penetrating it regardless of gauge. One could use tougher insulation (Teflon, Kynar (typical of wire-wrap wire), etc) but you'll pay more for it. It'll be a little tougher to strip for the same reason.

In Brian's case, the paralleled wires of a smaller gauge *MIGHT* be a tiny bit smaller, but I'm not sure the gain is worth the effort. If he were to go with seven #38's, the stacked diameter would be a bit bigger than the original wire (not factoring in the insulation of either). He has to decide that for himself. Speaking only for myself, I would use the original wires of the Loksound decoder, they're pretty small already. TCS has thin insulation wire available as well.

Lyle

eta: I do find the wire on ESU decoders to be a tiny bit more brittle than the TCS wire.

[Deleted]

I really appreciate the discussion. It is very helpful.

OK. This application is not for HO. It is N-Scale. That means area is at a premium price. I have to stuff a decoder, speaker and resisters under the hood. I will be using a Loksound Select Micro. The wires will be static. Not moving around or flexing.

My plan was to put the decoder in the fuel tank and the speaker under the radiator fans. Custom build a new PC board to make all the connections. Cut a channel in the side of the frame to bring the wires up. If I can get the decoder wires to flex and sit where I want them to, then I will just stick with them and not use the 38 gauge wire. Maybe what I can do is get a ball end mill slightly smaller than the wire with insulation diameter and cut an individual channel for each wire. Then press the wire into it. I want my PC board to have the connection point right at where the wire comes up the side of the frame so there is a minimal route path. I'll try to fit surface mount LED's to the PC board for the lights.

Thanks for the information. As usual, this group comes through for the modeler.

[lyled1117]

Brian, I was going to recommend another site where several peoples are doing n-scale sound install, but I went there to get a link and found you're already there. You've seen some of jdcolombo's stuff, I've been referencing some of his work to get ready to do a large number of installs for a customer.

Lyle

[Deleted]

Yes, I have been looking at John's installs and am very impressed with what he has done. Using his installs as a base for mine.