# Decoder influence during transition between power districts



## johnfm3 (Sep 30, 2016)

I have a Athearn Diesel loco which has the front and rear truck pickups wired together. Left to Left and Right to Right (captain obvious here). I have a single pair of wires ready to goto the decoder.

Lets assume that I continue down this path and only have the 1 pair of wires going to the front or rear track pickup solder pads on the decoder.

Will this have a negative effect when the loco crosses over power districts when each district is powered by a different booster? I am questioning/concerned if the decoder has some internal circuity assisting in the crossing a isolation point between two boosters? Or is the boosters capable of dealing with this sitaution on thier own? Note that I am only asking where polarity matches and not a reversing situation. As the DR5033 are auto reversing as well.

As I see it. Running the loco this way would be the same as connecting the two boosters track outputs in parallel for a short period of time while the loco is over the isolation point.

In this case, I am running digikeijs DR 5033 boosters with a DR5000 command station.


Thanks,
John


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## mesenteria (Oct 29, 2015)

There should be no phase conflict unless you reverse the phase between districts. If the wiring is all in phase, or if you have a properly controlled reversing section, all the boosters do is to amplify the voltage AND the signal. The signal will always be within a fraction of a millisecond in synch, with such a gross separation in time on a very large layout with runs of track in the 1000' range(?) and beyond. Your decoders have a different sampling scale and won't notice any gap crossings.


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## johnfm3 (Sep 30, 2016)

Thanks for the quick response. This would be considered small in size. 13ft by 20ft. What about possible risk to the boosters during the transition? That is another fear I have.


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## Lemonhawk (Sep 24, 2013)

The more pickups on the loco the less chance it will fine a dead spot to stop on. Your doin it right by using both pickups, and the controller will not notice anything!


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## DonR (Oct 18, 2012)

John

Are you saying your layout is 13 X 20 feet? Is that only a section of
your layout, or is it the entireity?

The reason I ask, boosters on two 'power districts' seems a dramatic
power overkill for 13 X 20. Usually, only very large club type
layouts even consider 'power districts'. They do keep the rest of
a layout running when a member derails and shorts in one district
but are a costly excess for a home layout. Also, boosters are normally
not needed unless you are running a number of sound locos at the
same time.

Don


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## johnfm3 (Sep 30, 2016)

Don, My layout is currently 13x20 with the expectation of being enlarged during the remodel of house to 3 locations of this and larger.

I know its other modelers opinion that its overkill to have multiple boosters in a layout this small, the benefits (as I see it) are worth the extra $80 I pay for another booster which is a small price as compared to a $1000 loco or $2000 in a full passenger train with decoders and sound decoders in all passenger cars and a ABA set of E9's pulling it. You are not the first person to express this opinion to me. The nessessity of my having multiple boosters really is not relevant to the question at hand. Only issue is what happens as my loco changes between power districts with my front and rear pickups paired to the same solder tabs on the decoder. 

The only real concern I have, Is there any risk to my loco's sound decoders or DCC boosters with my loco wired as such.


Thanks,
John

BTW: ALL my loco's will be full sound with the obvious exception of the Dummy B units I still have. LokSound and Tsunami2 are my decoders of choice. All my passenger cars will have light decoders. And some will have Tsunami SoundCar decoders for added sound effects of the whole train. SoundCar even has livestock sound effects for cattle and sheep.


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## gregc (Apr 25, 2015)

the decoder is not sensitive to any phase or voltage differences between the two districts at the boundaries or likely to be damaged. it is unlikely any small phase difference will cause data corruption since the difference between a 1 and 0 bit is 58 and 100 usec

however, the metals wheels bridging the gaps between the rails may cause a momentary short if there is any phase differences (~ usec) and any voltage difference is momentarily equalized, drawing slightly more current from one booster than the other.

shorts are of course common place with DCC trackage since their detection is used by auto reversers and frog juicers.


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## johnfm3 (Sep 30, 2016)

Ok, based on the replies and no one addressing this part of my concern, there is no reason to worry about any risk to the boosters (which I am more worried about) if they are joined as 1 for a short time during the transition of the loco from front till rear crosses.

I am concern as I see this the same as wiring 2 boosters in parallel to the same rail for a short period of time while the loco transitions. Assume 5 seconds or so, possibly multiple times depending on how many loco are in lead.


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## DonR (Oct 18, 2012)

All boosters and track sections should be of the same phase...2-5 amp boosters
shorted together by train wheels where 'power districts' abut could damage the boosters.
It is a short circuit. If a lighted passenger car with one truck in 'district A' and the other
truck in 'district B' shorts your system, flip the output wires of ONE BOOSTER. That should
make them 'in phase'. Do this at each insulated joint until you no longer get a short.
Use a lighted car, not a loco as a short of that magnitude could damage the decoder.

The exception to the above is in the event there is a 'reverse loop' or 'wye'.

Don


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## johnfm3 (Sep 30, 2016)

It sounds like the short answer to my question is there is no risk to my decoder or boosters with my loco wired up as described in the original post. I recently received responses from SoundTraxx and DigiKeijs stating that there is no need for concern with my Loco Wiring burning up the decoder or booster.

John


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