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Post by dave on Mar 15, 2018 8:51:52 GMT -5
So, I might be looking at having decoders put in a couple of AZL locos. I have an NCE PowerCab DCC system with power supply. For Z-scale, do I need to reduce the voltage going to the tracks from the NCE system? If so, what is the best and easiest method to do this? If not that, what needs to be done to make the DCC work and not fry locomotives. Thanks for your help.
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Post by markm on Mar 15, 2018 12:05:26 GMT -5
You didn't mention which AZL locos. The "modern" ones that take the drop-in decoders (Z123z0 and AZL4) are rated at 12VDC and can be run with the PowerCab. I've had no problem and haven't found a need for a power booster. As for the others, there has always been considerable discussion as to the need to reduce track voltage. The easiest way to reduce the voltages is Digitrax UP6Z unit.
Mark
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Post by shamoo737 on Mar 15, 2018 12:13:37 GMT -5
You don’t need a voltage reducer. I never have a problem with high voltage using the Powercab. I did have issues when I tried a voltage reducer. I do recommend a short circuit protection.
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Post by dave on Mar 15, 2018 12:57:35 GMT -5
Shamoo, what do you recommend for a short circuit protection?
I should also mention that a Marklin Commodore Vanderbilt will get a decoder. That is probably relevant information.
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Post by shamoo737 on Mar 15, 2018 13:19:57 GMT -5
I use NCE CP6.
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Post by Greg Elmassian on Mar 23, 2018 15:58:32 GMT -5
I'd measure the voltage to the tracks and keep it to 10 + 2 volts... I picked the power supply to set this... and I got a regulated supply.
Greg
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Post by texrail on Mar 23, 2018 16:26:29 GMT -5
When the Marklin loco is mentioned, does that mean, marklin locos don´t stand 12 Volt? What about MTL-locos? Can I have 12 Volt on the rails but reduce the power pickup for the motor by the decoder?
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Post by markm on Mar 23, 2018 17:15:49 GMT -5
Most Märklin locomotives are rated at 8VDC the rest 10VDC. The MTL F7 is rated at 8VDC, the GPs rated at 9VDC. With a DCC 12V track, the decoders will supply a little less than track voltage as pulsed power. From this point there are several camps. One is to reduce the track voltage to 10V like Greg. Another is to program the decoder to 10V maximum. The decoder still outputs 12V pulses duty cycle is limited to 5/6 the track.
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Post by texrail on Mar 24, 2018 10:17:53 GMT -5
Mark, can you please explain what does it mean?  Thanks, Ingo |
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Post by markm on Mar 24, 2018 10:35:49 GMT -5
Ingo, DCC decoders use what's known as Pulse Width Modulation (PWM), or at least all the decoders I'm familiar with. So, when you are running at a slow throttle, it sends out a string of narrow pulses which average out to a low voltage:  As you increase the throttle, the pulses get increasingly wider, which averages out to a high voltage:  To limited the maximum average voltage of the decoder output, there is a variable in the decoder (CV5 as I recall) that will limit the maximum pulse width the decoder will output. So to limited the output to 10V on a 12V track, the fraction is 10/12 or 5/6. The variable in the decoder has a range to 255 (100% of track voltage) so to run at 10V it gets programmed to 5/6 * 255 or 212. Hope this clears things up, Mark |
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Post by texrail on Mar 24, 2018 13:23:18 GMT -5
Mark,
thanks a lot for the explanation !!! Now I understand.
Best regards
Ingo
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Post by shamoo737 on Mar 24, 2018 14:06:26 GMT -5
I used to limit the voltage, but I found out if you don’t run it like a rocket, you will never reach the limits.
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Post by QcKraag on Mar 24, 2018 21:11:03 GMT -5
Not quite true since on dcc the max voltage is always on the track, I control voltage straight on the power supply, but rthe n them all on dcc at 12v, there is a danger to older micro-trains and marklin, but I have none of those
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Post by shamoo737 on Mar 24, 2018 23:21:26 GMT -5
I been running dcc since 2002, and never a problem with high voltage, and I run MTL and early 8V AZL. In fact, I think it’s a waste of money and time to reduce the voltage. I do strongly recommend a short protection.
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Post by Greg Elmassian on Apr 9, 2018 15:43:59 GMT -5
$5 for the parts to drop the voltage is cheap insurance.
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