On my very basic DC layout I have a problem which I would certainly atttribute to voltage drop. The layout is basically a very simple dogsbone and on the furthest away section, furthest away from the power source, the trains slow down, not progressively, but suddenly. They pick up again when they round the curve and come back into the "power" straight. At present that back straight is isolated from other track, although it will be connected up later, I hope. It's the suddenness of the apparent loss of power that is mystifying, as I say, it's not a gradual thing. Any ideas?
Voltage drop
- Thread starter Glengrant
- Start date
My guess would be a duff rail joint somewhere Cyril. Give your rail joiners in that area a nip with some pliers and see if that makes any difference.
Gotta be two high resistance joints. Restistance likes electricery, it eats it. No good running round wiv a voltmeter as its the amps it likes not the volts.
I agree with the above but I would also put a feed into the track at each end so it is less affected by iffy rail joiners
Yes, as has been said this sort of slow-down is generally due to a high resistance joint or two, so the first thing to check is the fishplates.
What I tend to do is run a slow loco that obviously slows down over the problem section of track, follow it round with my favourite pliers in hand and as soon as I see an obvious drop in speed I use the pliers to bridge the rail joints behind the loco and see if it speeds up - this will then indicate where the dodgy joint is that needs attacking, by tightening and/or sliding back and forth to clean inside the fishplate.
I'm slightly confused where you say
Are you saying that you have separate feed wiring to that back section? It may be that the wiring used isn't large enough for the amps required?
What I tend to do is run a slow loco that obviously slows down over the problem section of track, follow it round with my favourite pliers in hand and as soon as I see an obvious drop in speed I use the pliers to bridge the rail joints behind the loco and see if it speeds up - this will then indicate where the dodgy joint is that needs attacking, by tightening and/or sliding back and forth to clean inside the fishplate.
I'm slightly confused where you say
Glengrant said:
Are you saying that you have separate feed wiring to that back section? It may be that the wiring used isn't large enough for the amps required?
bobg said:Gotta be two high resistance joints. Restistance likes electricery, it eats it. No good running round wiv a voltmeter as its the amps it likes not the volts.
You can measure if you put a load on the track.
If you put on the load on the track (motor?) then you can measure between rails and should see a lower voltage where the trouble is. Theoretically you should then be able to measure a voltage across the bad joiner as well.
I have usually just put in more feed wires instead of trying to pinpoint such things
Sounds like you have a bad connection and the power has to come from the "far side".
Does the problem manifest itself the same way if you drive the other way around, or is it so that when going the other way the speed gradually drops while suddenly going back up?
OK I think I am getting the gist of this, and no, there is not a separate feed to that rear section, it is now obvious that there ought to be. As soon as this pesky rain goes off I am going out to check all those joins and also introduce a separate feed to the rear section. Thanks all of you for your advice, good G-scale stuff this
Incidentally, sorry Nick, I worded that bit badly. The circuit goas all the way round the dogsbone, what I was trying to indicate is that there is a turnout on the back nit on to another separate bit of railway, separate TE in fact, but it is not electrically connected up at present so there is no leakage of electricity there.
Don't forget it always takes TWO to tango, one bad joint will NOT cause a problem you always need two bad joints to cause aggrovation you have to have a space between two joints to cause a voltage drop..............................
minimans said:
It takes two indeed, but one of the two can simply be distance. When the power has to go "the long way"you end up combining all the resistance of all the joints and it does add up. Good joiner or not.
I had that myself once. There was one faulty joiner close to the power pack so the power had to go around the other way. About 15 meters or so. Aristo and LGB track. And it did add up
Heres a tip for finding bad joints on analogue
I have a diesel loco with phoenix sound and the engine revs drop as soon as the voltage does. This is quit sensitive so when I run it round if the engine note changes but I haven't touched the TE I know exactly where I have got a dodgy joint. I have found this happens as the joint is starting to go downhill and before there is any noticeable drop in speed.
So there you have it - you need to invest in a sound card for technical reasons and not for the joy of having a sound unit.
And of course you have to have it quit loud so you can pick up any changes in engine revs.
I have a diesel loco with phoenix sound and the engine revs drop as soon as the voltage does. This is quit sensitive so when I run it round if the engine note changes but I haven't touched the TE I know exactly where I have got a dodgy joint. I have found this happens as the joint is starting to go downhill and before there is any noticeable drop in speed.
So there you have it - you need to invest in a sound card for technical reasons and not for the joy of having a sound unit.
And of course you have to have it quit loud so you can pick up any changes in engine revs.
Another reason to solder jumpers between all rail ends. Or to put it another way, solder jumpers across all rail joints. Also, I have found that using larger wire to supply power to the track helps with voltage drop. I use old extension cords that I find. The heavy orange type. Usually 12 - 16 gauge, of the type used by the trades. I have used quite a bit of it. Not only for power to the track, but also for the EPL system wiring. One other advantage of using it in an established garden, is that when any digging needs to be done, it is shovel resistant, and easily found, due to it's orange color.
Madman said:
Dan
Wire 'gauge' doesn't make a lot of sense to us limeys - what is that in current carrying capacity?
We can buy that suff over here, usually in Chandleries, because all marine grade electrical wire in this country comes from your side of the pond :-
Rhinochugger said:
I'm a bit confused. When you say,"We can buy that suff over here, usually in Chandleries", what do you mean. Also, do you consider extention cords, "marine grade"?
I did not realize that. 12 gauge wire is usually good for 20 amps, 14 gauge, 15 amps. I am not sure what 16 gauge is rated for, but it is rare on construction sites.
Do you mean that we actually manufacture something that we can sell to you?
Madman said:
No!
Here all cables and wire are sized in mm²........in teaparty land they are American Wire Gauge.
AWG sizes don't equate to exact mm².
12AWG = 3.3mm² our nearest would be 2.5 or 4mm²
14AWG =2.08mm² our nearest would be 1.5 or 2.5mm²
16AWG =1.31mm² our nearest would be 1.5mm²
Here are the current capacities of common UK cables.
These ratings do vary a little bit relative to how and where the cable is put
ie it's temperature rise.
1.0mm - 13A
1.5mm - 16A
2.5mm - 21A
4.0mm - 27A
6.0mm - 34A
10.0mm - 45A
16.0mm - 57A
Madman said:
Yip
For marine grade electrical wire, you need strands that are tinned, I forget what with, to prevent corrosion from salt.
I've never found any marine cable that is expressed in English terms, and so I've always assumed that is made by Uncle Sam. A lot of marine electrical parts are brought over from your little country as well, but some of them are a tad pricey :bleh:
I was just casually interested, to see whether my american friend was looking to sign up as the second member of the cooker cable club.
Sadly, it seems, no :Looser:
Sadly, it seems, no :Looser:
Rhinochugger said:
Similar cable is used in submersible pumps......the type H07RHF and H05RR-F.
Now I have seen this in untinned and tinned, in good quality pumps its tinned in lesser
ones it's not........the sheath is normally EPR but not armoured.