Check the figures in the MR reviews of BLI and other sound locos - few if any of them draw .75 amp even stalled. Most are .5 amps and less. ANd that's usually the stall current - ie you hold the motor so it can't turn, so even pulling 40 cars it won't draw the stall current. 3.5 amp DCC system can run plenty of locos, and is even big enough for you to add a couple of extra throttles and have a couple of friends over running trains as well, unless you want to try for some wierd record and have 10 locos on each train. Three double-headed trains though, that's perfectly doable with a 3.5 amp system in HO and smaller scales.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rampmeter: http://www.tonystrains.com/products/tteexclusive_measure.htm
Your figure of .75 A per loco is at least double for today's modern models. A closer figure would be .2 to .3 per loco. As mentioned by another poster, it's only at start-up with multiple sound equipted locos that there might be an issue, but with 3 plus amps of power that's not likely tro be an issue either. Get the rampmeter if you're concerned. All DCC owners probably should have one.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
loathar wrote:OK. By any chance have a link to what you have there? I'm assuming the top read out is voltage?
http://www.trains.com/trccs/forums/1016761/ShowPost.aspx
loathar wrote: Thanks Alan! I was figuring .75 amps per loco. 3.5 amps should be plenty for 4 or 5 locos then. That saves me quite a bit of $$$.
Don't save all of the booster money - buy a RampMeter and then you will know what is going on.
The 0.39 amps in the photo below is with two sound engines running and 4 idling with sound on.
loathar wrote: I'm leaning towards the PA system. I've heard that their 2.5 amp rating is a little liberal so I want to make sure I've got enough power. Their 5 or 8 amp boosters alone would be more than enough power for the whole layout. (8'x15' with about 200' of track) I figure the most locos at one time will be 5. two double header freights and a single switcher. Might upgrade to a few sound units as $$$ allows so I don't want to be under powered. Can you use the base unit only as the "brains" and the booster only as power for a single district layout? (don't know if I'm explaining this right) I mean, don't use the 2.5amps of power from the main unit. Just use the booster to power the whole layout? I'm pretty much set on an MRC product, so please, no 3 pages on why I should buy a Digi system.
I'm leaning towards the PA system. I've heard that their 2.5 amp rating is a little liberal so I want to make sure I've got enough power. Their 5 or 8 amp boosters alone would be more than enough power for the whole layout. (8'x15' with about 200' of track) I figure the most locos at one time will be 5. two double header freights and a single switcher. Might upgrade to a few sound units as $$$ allows so I don't want to be under powered.
Can you use the base unit only as the "brains" and the booster only as power for a single district layout? (don't know if I'm explaining this right) I mean, don't use the 2.5amps of power from the main unit. Just use the booster to power the whole layout? I'm pretty much set on an MRC product, so please, no 3 pages on why I should buy a Digi system.
I have the PA and it is 3.5 amps not 2.5. Spend the booster money (or part of it) on a RampMeter to monitor your actual voltage and current consumption. You should not need a booster with 10 or fewer modern sound loco's running. If the RampMeter shows that you are drawing 3 amps or more, then get the booster (I don't think that this will ever happen). Yes, I have a RampMeter and two of my sound equipped engines running at one time, with 5 others' idling with sound turned on, draw less than 0.4 amps.
Again - you should not need a booster.
loathar,You don't need another booster. 2.5 amps is more than enough power for 5 HO locos...even sound equipped ones.
If you run into any problems, it will be on initial power up and a recovery from a short circuit. See, the capacitors in each sound unit tries to charge whenever it gets power (called "in rush current"), and all the engines charging capacitors at the same exact instant can cause the circuit breaker to trip and not reset properly. To solve this, either you need more power (ie., more boosters) or what you need is the new PSX circuit breaker from Tony's Train eXchange (www.tonystrains.com). IIRC, it has a new feature that allows a "slower", more gradual build up of power that allows the capacitors to charge without tripping the breaker.
A PSX costs a lot less than a new booster...
Paul A. Cutler III************Weather Or No Go New Haven************
You'll need to divide your layout into two power districts with one booster for each. Don't try to combine two boosters on the same block. And make sure the two boosters are in phase or it can cause problems when a locomotive crosses from one power district to the other.
Unless you're planning a very large layout or you think you'll be running multiple trains simultaneously, one booster should be sufficient as long as you provide an adequate number of power feeds from the main bus.