Problem on the site caused a dual posting.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
They come in a variety of sizes. The 3M 905 accomodates 18-22ga for the tap and 18-14 ga for the run
AC signals are affected by inductance and capacitance. I would think any affect is very small because their values are both small and DCC is at relatively low freq (<10kHz).
the other benefit of DCC is that while voltage drop does affect the voltage reaching a decoder, the decoder may not be applying full voltage to the motor and can maintain a constant motor voltage when using BEMF.
my understanding is that for the 905, it accomodates 14g stranded or 18g solid (run).
You have to double those voltage drop calculations - if the feeder is in the middle, and the loco is 130 feet away from the feeder, that’s 260 feet of ‘wire’
–Randy
right. thanks
I suspect I am about to be schooled on the subject, but my recollection of my old Navy electronics training says that there IS an electrical difference, at least between wiring of the same gauge. I was told that current does not pass through the entire mass of a wire, but on its surface. On that basis, 14 gaage stranded, having a far greater total surface area per unit length than solid, has a greater efficiency (less resistance?) to pass current. Now, for our applications, those effects may well take a back seat to other ones like flexibility, especially on smaller layouts with shorter busses. Guess I’m mostly nit-picking here, with a hat tip to Betamax for his post.
But now that I think of it, much of the stuff I heard in the Navy on virtually every other subject was highly suspect. That spirit sometimes made its way into technical, classroom subjects to embarass both the simple and the unsuspecting!
[;)]
John
The simple answer is that DC is not the same as DCC.
With DC, as your locomotive slows you crank up the voltage a little more.
With DCC, the decoder controls the speed, as the voltage decreases it will slow down as the motor is controlled using PWM, where time, not amplitude, determines the speed.
The more complex answer is that DCC, being a square wave, is rich in harmonics. Harmonics do no work, but they do cause problems. Hence the need for more robust wiring.
Thanks.
At audio frequencies, the skin effect is minimal. Especially considering the currents involved.
At high currents, it is all about the surface area. Even at 60Hz.
Perhaps on a grade with a heavy train, but for the episodes with the dozen locos, the throttle was set to a medium-slow speed, and not adjusted at all.
My DC walk-around throttle also puts out PWM current - perhaps that explains the situation, although none of my locos have decoders.
Wayne
I operate dual mode and the newer more efficient can motors don’t seem to slow down with increased load as much as the older motors. In DC mode the older Athearn SD40-2s with the original motor did slow down as they pulled my 3½% grades but after remotoring them with can motors it’s hard for me to see any speed decreasing.
I have 10 ounce passenger cars and my norm is 11 cars per train and a pair of dual can motored Athearn SD40-2 frame with Cary E7 bodies doesn’t seem to drop speed climbing my grades.
I run at about a scale 50MPH and on flat track the four can motors draw around 280ma pulling the 11 cars. On my 3½% grade the motor current increases to about 500ma. I have a panel volt meter on the track power as well as the ammeter and the voltage drops about a half volt at the grade. The same configuration with original motors was very high current, from around 700ma for both locomotives to almost 2 amps and over a volt drop using the same power pack (MRC7000).
When running in DCC mode to make it look realistic I have to decrease the throttle for them to slow down running the E7s, even the sound doesn’t sound labored. When pulled by a single DCC Rivarossi Cab Forward I can hear the difference as the locomotive is worked harder.
My preference is stranded for bus wire and 22 ga solid for track feeders.
Me too.
You want the red ones. 22-18 Awg (Tap), 18-14 Awg (Run)
I guess I’m one of the few that is all about solid core wire. i use 14 guage for bus wires and 22 gauge for feeders. I solder all my feeders with gaps approximately 2 inches apart on the bus wires to prevent accidental shorting. I also use 26 gauge Cat 5 cable for all my block detection and Tortoise switch motor wiring.
It is more difficult to pull but I built wire traces into my benchwork (open grid 1x4). Each 1x4 cross member has two 2" holes cut to run wires though the benchwork. This makes running wire super easy.
The only stranded wire I use is for my 12VDC accessory bus and that is 18 ga stranded because I got 6 500’ rolls of it for free.
Honestly I prefer the solid core wire. Easier to strip insulation without cutting strands. I don’t have to worry about adding connectors on the end of the wire like I do when I want Stranded wire to go into a terminal block. 14 curls around screws in the terminal blocks quite nicely.
I also like solid wire because it makes great piping for things like refineries. I know its not be primary use but its makes a great alternative.
951 accommodates 22 to 18 AWG solid/stranded, 952 accommodates 18 to 14 AWG solid/stranded and 953 accommodates 12 AWG solid/stranded
when is says "22 to 18 AWG solid/stranded", i got the impression that means 22g solid or 18g stranded. I’ve used the red ones with stranded wire (run) with them and found that it cuts some of the strands.
Yes, I would say you probably are one of the few.
A proper strip tool strips sections in the middle of the run on stranded or solid without breaking the wire. I offset my feeder connections as well because it’s often months before I go back and insulate them - last layout I never did. But since they were offset, there was never ever a short. Solid feeders make perfect sense - far easier to push through the hole next to the rail. But even with holes drilled through the benchwork crossmembers, pulling out solid in heavier gauge wiring is harder - maybe not from one end of a straight secion of benchwork to the other, but around that first curve and the stranded just keeps going.
For the multiconductor stuff - either or, but the connectors fo
I take it to mean 22 to 18 AWG solid or stranded.
I’ve put 14 AWG stranded into them without cutting strands.
I had 6" each of 14 AWG stranded and 22 AWG solid in one of these sitting on my desk for years that I fiddle with all the time. Every now and then I check for continuity and have never had a problem. Not exactly a controlled experiment, I know.
why does the description say “solid/stranded” if it doesn’t matter?