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Post by loco8107 on Jan 17, 2021 11:06:24 GMT -8
This past Christmas season I set up a loop under the tree. It was 6 18” radius curves on each side (12 pieces total) with a 3” straight piece at the 12,3,6 and 9 o’clock positions. I ran all my locos- the P1K GP15 was the best performer but the BB SW1500 and GP38-2 ran well too altho I will upgrade both. The Atlas master GP38 ran well to but I was surprised the BB units both used less throttle to run than the Altas unit . The Proto was about the same as the BB’s. In fact the red indicator lights on the Tech 4 power pack lit up more lights for the Altas unit (and ran at slower speeds) which I thought was weird. I always believed the BB units used the most throttle. Is this normal?
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Post by loco8107 on Jan 17, 2021 11:08:18 GMT -8
Also - the board is a square 42” all around and at the opposite end of the wire connector to the power pack (Atlas track code 100) on the layout, all locos slowed a little before getting back to speed. Any thoughts on why?
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Post by edwardsutorik on Jan 17, 2021 11:15:40 GMT -8
Also - the board is a square 42” all around and at the opposite end of the wire connector to the power pack (Atlas track code 100) on the layout, all locos slowed a little before getting back to speed. Any thoughts on why? That one APPEARS easy. There's voltage drop in the rails/rail joiners, so the voltage is lower farthest away from the wire connection. I am surprised that it would be noticeable in just a loop of track, however. Ed
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Post by loco8107 on Jan 17, 2021 11:21:59 GMT -8
Also - the board is a square 42” all around and at the opposite end of the wire connector to the power pack (Atlas track code 100) on the layout, all locos slowed a little before getting back to speed. Any thoughts on why? That one APPEARS easy. There's voltage drop in the rails/rail joiners, so the voltage is lower farthest away from the wire connection. I am surprised that it would be noticeable in just a loop of track, however. Ed The same here which is why I asked. Definitely odd.
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Post by loco8107 on Jan 17, 2021 11:23:39 GMT -8
What is the solution to that?
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Post by jonklein611 on Jan 17, 2021 11:27:51 GMT -8
What is the solution to that? Feeders on the other side of the loop. Check your rail joiners for tightness, clean track and all connections, etc.
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Post by edwardsutorik on Jan 17, 2021 12:07:13 GMT -8
What is the solution to that? I suspect your rail joiners are loose. They need to be a tight fit on each end. To see if that's the problem (and then repair it, if it is), you'll have to disassemble the loop. Anywhere there's a loose fit (on EITHER end of the joiner), you should fix. That can be done with a replacement joiner that is a tighter fit. Or you can squish/squeeze the existing joiner just right, and put it back on. That's how I used to do it when I used sectional track. Remember: the joiner must fit tightly on each of its ends. Ed
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Post by llxlocomotives on Jan 17, 2021 14:19:02 GMT -8
You have a 10.4 foot loop of track. Track with joiners are terrible electric circuits. Voltage drop occurs at every joint to varying degrees. This is one of the reasons that the DCC practice is to provide feeders at every section, at least every three feet. The buss becomes the main path for the circuit. It still has a voltage drop per foot of run depending on wire gauge, but much better than track with connectors. Your observing the speed voltage function for the various motors, particularly if your pulling a train behind the loco. I am finishing my motor DOE test series, and one interesting impact is the speed loss that occurs with a nominal train at a fixed voltage. Your described engines would show significant differences if the voltage was fixed. It will be further amplified by the losses occurring in the loop. If you put this up again next year, think about adding additional feeders. A total of three would probably be enough. You might get by with two, it will depend on how much speed sag you are willing to accept.
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Post by lvrr325 on Jan 17, 2021 15:02:42 GMT -8
BB locos have zero electronics which I think lets them run faster at less throttle. Sound units definitely use more voltage to run at the same speeds, a friend who's tried to run both together (on DC) has complained about it.
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Post by Funnelfan on Jan 19, 2021 23:24:07 GMT -8
The Atlas unit has a constant lighting circuit on the motherboard that is taking up a signifigant amount of power before the engine runs. It's not anything to worry about, just the way it's designed.
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Post by loco8107 on Jan 24, 2021 7:25:41 GMT -8
The Atlas unit has a constant lighting circuit on the motherboard that is taking up a signifigant amount of power before the engine runs. It's not anything to worry about, just the way it's designed. Gotcha. Odd the P1K GP15 has the same thing as Atlas but runs faster.
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Post by llxlocomotives on Jan 24, 2021 12:30:57 GMT -8
Those “constant lighting” circuits were designed for conventional lights. Proto 1000 & 2000 were set to keep the motor from starting below 4 volts. I have seen that start voltage to be as high as 5 volts. The problem is that voltage control(loss) does not totally go away at high power. I have run the same engine bypassing the module. The motor would sustain velocity around 2 volts in that case. The velocity voltage curves were parallel. Thus the module case never reached the max speed of the bypassed case. Modules vary in performance, as do motors, so that is likely leading to the difference between the Atlas & the P1K engines. Depending on the model the truck gear ratio may be contributing to the difference. A digital control system would allow you to set the speeds individually if needed.
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