DCC Question

[RR_Mel]

I was wondering if anyone has paralleled to like motors off one decoder.  I have a pair of matched Mahsima motors that draw less than 500 ma at full load.  I’m remotoring a pair of HO Athearn SD40-2 frames/Cary E7 bodies with the Mashima motors.  The weight of both locomotives is the same at 2.4 pounds.

 

The two E7s ran perfect on my layout on DC, with them uncoupled they ran the same speed around my 110’ mainline loop staying within a foot of each other in two complete loops.  My mainline has a 3½% grade straight and curved up and a helix down.   

 

There are two reason for this approach.  1) cost of a second sound decoder, 2) I have always had a problem programming two locomotives to run together in DCC mode without some difficulties.

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

[richg1998]

I have a HO NYC F3 A and B run by one decoder in the A unit. Motor and speaker in each unit. Close couple, you don't see the connector in the diaphragm unless on a sharper curve.

Runs very well with an NYC F7 in ABBA. The F7 A and B each have their own sound decoder and speaker.

Rich

[selector]

Rich, honestly, I am happy you are able to report that such an arrangement works for you.  My first concern, really the only one, is that the one decoder has a rather modest limit in terms of how many amps it can tolerate in throughput.  Even if it's a whopping 2 amps, two motors trying to compete with amplifiers on the motherboard AND pull a decent trailing tonnage up a 2.2% grade could get that one slim decoder right up to its max, and that's not normally a good condition to run in for very long.  I guess the real numbers would dispell my concerns, though.....

[richg1998]

When I get a chance, I will try to measure the total current draw. The F3 is a BLI PCM lash up set. I believe it is a LokSound decoder.

The BLI refurbished DC F7 has a TSU-AT100 and speaker in each one.

The ABBA set pulled 40 NYC Pacemaker NMRA weighted freight cars and brass caboose on the club layout which had a 2 percent grade but all working together I guess made it easier for the PCM set.

Rich

[RR_Mel]

For a test I ran both locomotives after the remotor on DC pulling my 10 car passenger up my grade and the maximum current was well under one amp.  Even at 2.4 pounds each when I stopped them by holding the first car after the locomotives the wheels slipped at 987ma (12 VDC) measured with my Fluke.  The proposed decoder is rated at 1½ amps continuous.

 

I’m not as concerned about current draw as I am with the two motors fighting each other running off one decoders power.  I’ve had problems running a consist using two decoders descending my 3½% grade.  Everything works great in DC mode.

 

The decoder was in a Athearn SD40-2 Frame/Cary E7 shell with a stock Athearn motor that would draw about the same current as both Mashima motors.

 

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

[RR_Mel]

After spending about 6 hours testing my DCC decoder/Mashima motor I’ve decided to go with two decoders.  The motor running off  the DCC decoder is not as efficient as it is running on DC.  To get the same RPM from the motor the current increased from .47 amps on DC to .64 to .66 amps through the decoder.

 

The decoder has a max current of 1.5 amps and I do not want to push my luck by running it at a constant 1.32 amps.  I’ve been using DCC for over ten years and never dinged a decoder.

 

 

 

 

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.