onrman3I have an MRC dcc 10 amp power supply and a dcc booster with an additional 3.5 amps
He doesn't have power districts/blocks? So he using the 10 amp power supply from the DCC system and the 3.5 amps from the booster at the same time on the same tracks? That could be the problem if that's the case. Maybe have him try running the engines just connected to the main DCC system.
He only runs locomotives and it is a shelf layout that goes around his family room - the size of a modest living room I do not believe he has created power districts. I did this with my large DC layout and he was intrigued by it but did not follow with his dcc.
onrman3 Here is the answer from my brother-in-law. I have found some of the information for you. The one that got me going about the pulsing hum/ low throbbing sound is an Intermountain ET44AC. My newest locomotive arrival. My military tribute loco in an Athearn Genesis SD70-ACu 7021. Have not searched the big suitcase for the other one yet… I have an MRC dcc 10 amp power supply and a dcc booster with an additional 3.5 amps. The sound in continuous around the entire circuit of the room.
Here is the answer from my brother-in-law.
I have found some of the information for you. The one that got me going about the pulsing hum/ low throbbing sound is an Intermountain ET44AC. My newest locomotive arrival. My military tribute loco in an Athearn Genesis SD70-ACu 7021. Have not searched the big suitcase for the other one yet…
I have an MRC dcc 10 amp power supply and a dcc booster with an additional 3.5 amps.
The sound in continuous around the entire circuit of the room.
And the answer was???????????????????
How big is the layout? And, was a lot of care taken to use heavy bus wires all around the layout, with a lot of feeders to distribute power to the tracks? Is the DCC power used for anything else other than locomotives?
That seems like a lot of power for an average home layout. Is the layout broken into power districts with insulated rail joiners or track gaps and separate circuit breakers? Yes or no to this probably wouldn't cause the throbbing problem, but putting so much power on the tracks risks actual damage to electronics if the power available to the track is too high and an undetected short occurs.
It takes an iron man to play with a toy iron horse.
I, too, would first ask about the conditions under which this happens. What DCC system is in use, and how much power does it have available, including boosters? Are there circuit breaker districts which might limit power? Does this problem occur everywhere on the layout, or only on certain sections of track? Does this happen with individual locomotives, or only when these three are running?
There is a DCC feature called Back EMF, which allows trains to maintain constant speed on grades when pulling a train. This feature is not available on all engines, and may be enabled or disabled with a CV setting.
I'm not sure what you mean by a throbbing sound when the sound is off. And the fact that 3 different locos are doing this is very strange. You might want to provide information about the DCC system and the locos (brand, model, age). Do these locos have a "regular" sound on another layout? If yes, that would suggest a problem with the system or the layout (such as dirty track).
Simon
My brother-in-law is experiencing with three of his HO scale DCC locomotives a throbbing sound when the units operate and the sound is turned off. I am just wondering what this is? There is no impact on their operation. The units are from different manufacturers. Any advice?