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| | |-+  The difference between DC an DCC, the Dutch way.
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Author Topic: The difference between DC an DCC, the Dutch way.  (Read 2531 times)
dutchbuilder


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« on: January 23, 2017, 08:51:50 PM »

I get the impression, frequenting this forum,that a lot of beginners don't have a clue what DCC is and what the difference is between DC and DCC.
Here is an attempt.

The difference between DC and DCC the simple way.

First DC.
The controller produces a voltage between 0 and lets say 12V Direct Current.
When turning the control knob you give the motor of the locomotive an increasing amount of electrons causing the motor to turn faster and faster.
When turning the knob the other way the locomotive will go slower and stop in the end.
Some controllers have a knob that turn to the right and to the left of a zero point.
There are others that have a toggle switch.
Both change the polarity of the controller from +/- to -/+ causing the locomotive to run the other way.
There are also controllers that simulate acceleration and deceleration.
But that's a different story
Simple so far?

Now to DCC.
Better known as Digital Command and Control.
A controller with DCC will send a digital signal comprised off 1's and 0's ( on or off's) also known as binary to a receiver on the locomotive.
The receiver/decoder in the locomotive will convert these into understandable commands.
The carrier with DCC commands looks like AC, not DC.
Every locomotive on track has a specific name or address.
Every signal send from the controller first sends that address and then the information what the locomotive has to do.
So only the locomotive with the right address will react.
An advantage of DCC in comparison with DC is that you can run several locomotives on one track completely independent of each other.
 For example; If you want an head on collision, not recommanded but no problem.
You can also program the decoder specifically for that locomotive.

This is what I understand DC is with an extra C.

I hope this is simple enough explanation for anyone who wants to start with DCC.

Ton
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railexpert


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« Reply #1 on: January 24, 2017, 11:22:23 AM »

Hello Ton,

you forgot something important:

Depending on the DCC control center, there is a constant circuit with a voltage between 15V and 20V.

The DCC signals from the control center are modulated on this voltage.
They are sent from the control center to the locos, where they are translated into motion commands or function commands by the decoder.

The necessary current for motion and functions is supplied to the loco by the constantly applied circuit.

Railexpert    Wink
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dutchbuilder


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« Reply #2 on: January 24, 2017, 12:48:20 PM »

I stand corrected.

Ton
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RAM

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« Reply #3 on: January 24, 2017, 04:02:10 PM »

what I don't understand is how you can operate a dc locomotive on dcc.  there is nothing I the locomotive to tell it what to do.
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richiy
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« Reply #4 on: January 24, 2017, 04:33:29 PM »

what I don't understand is how you can operate a dc locomotive on dcc.  there is nothing I the locomotive to tell it what to do.
\

Jim Banner explained that some years ago. EZ Command DCC controller and a couple other systems can do this.
Most systems today cannot.

http://members.shaw.ca/sask.rail/dcc/DCC-waveforms/DCC_waveforms.html

The DCC will cause the motor to buzz.
The motor will operate because it sees the positive or negative zero bits as DC.

With a decoder, the motor still sees positive or negative pulses as DC. It is called, PWM, Pulse Width Modulation. Twelve to fourteen volt pulses of varying width depending on speed.

richiy
« Last Edit: January 24, 2017, 04:36:36 PM by richiy » Logged
dutchbuilder


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« Reply #5 on: January 24, 2017, 05:04:14 PM »

My Lenz equipment can also run a dc locomotive using address zero.
Makes a lot of high frequency noise and run in the opposite direction as is normal.
I can't be good for the life of the dc motor.
That said, i use a PWM controller i bought in China on a pizza layout and it works very nice.
It uses 500Hz and makes a lot less noise.

Ton
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richiy
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« Reply #6 on: January 24, 2017, 05:20:15 PM »

I did measurements with voltmeter and Scope quite a few years ago.

Bought an infrared temperature scanner and the point where the brushes contact the commutator get hot and get hotter with the loco stopped as the AC component oscillates the armature. Reason for the buzz.
I had an old MRC2K similar to the EZ Command.
The scanner could also pick out the hot spot in a can motor also. I made a decoder tester some years ago and used some different motors as an experiment. It is hard on the motor.
There has been quite a lot of discussion about this in various forums over the years.
Always advised to park the loco on a siding and use a SPST switch to disable power to a raiil. Some like to use a DPDT switch.

richiy
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dutchbuilder


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« Reply #7 on: January 24, 2017, 05:39:07 PM »

This is a small movie i made of the pizza layout.
The porter runs on 500Hz PWM , no noise at all.
The controller is incorporated in the lampshade and the knob on top.
 
https://www.youtube.com/watch?v=kG5ryPGOFAs

Ton
 
« Last Edit: January 24, 2017, 05:42:00 PM by dutchbuilder » Logged
richiy
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« Reply #8 on: January 24, 2017, 05:53:17 PM »

Very nice. I gather you like to experiment with electronics.

richiy
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dutchbuilder


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« Reply #9 on: January 24, 2017, 05:57:07 PM »

full licence radio ham.

Ton
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richiy
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« Reply #10 on: January 24, 2017, 06:15:37 PM »

full licence radio ham.

Ton


That explains all.

I was Wn3rub many years ago but did not like CW.

richiy
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dutchbuilder


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« Reply #11 on: January 24, 2017, 06:21:40 PM »

CW is obsolete.
In the Netherlands all C amateurs were given a full licence after CW was abolished.
So i can use HF.
No interest, i specialize in TV and satellites and USA narrow gauge.  Grin
PA3 and PA0 amateurs are the one's with CW.

Ton

 
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WoundedBear
A Derailed Drag Racer


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« Reply #12 on: January 24, 2017, 07:08:04 PM »

what I don't understand is how you can operate a dc locomotive on dcc.  there is nothing I the locomotive to tell it what to do.
\

Jim Banner explained that some years ago. EZ Command DCC controller and a couple other systems can do this.
Most systems today cannot.

http://members.shaw.ca/sask.rail/dcc/DCC-waveforms/DCC_waveforms.html

The DCC will cause the motor to buzz.
The motor will operate because it sees the positive or negative zero bits as DC.

With a decoder, the motor still sees positive or negative pulses as DC. It is called, PWM, Pulse Width Modulation. Twelve to fourteen volt pulses of varying width depending on speed.

richiy

Again a reminder. Jim's old site is set to go away as of March 6 of this year. If you want any info from there. it's best to copy it now.

Sid
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richiy
Guest
« Reply #13 on: January 24, 2017, 07:41:07 PM »

Yes, I save pages like this to my PC. Easy to do.  With FF, click File, Save Page As. Add the name you like.
I double click that file and the page opens in my PC like it use to. Tough keeping track of those those pages though.

richiy
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dutchbuilder


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« Reply #14 on: January 25, 2017, 04:44:22 AM »

I had a look at Jim's site, interesting, if you know what he is talking about and you have a basic knowledge of electronics and computers.
It is still to technical and to complicated for Joe the User.
Joe isn't that much interested in how it works as long as i does the job.
It is nice to know.
That's why i tried to keep my explanation KISS.

Ton
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