Getting ready to add a LNRPXtra to layout which already includes a UR92 and two UP5 panels. The UR92 and the UP5 are currently powered via a Digitrax 14VDC PS14. The LNRP spec says it can use a 14-18VDC power supply. I have heard others say they have better results on Loconet by using 18VDC across the board.
My question is - is it OK to power everything with 18VDC?
I am asking this question because:
1) The UP5 and UR92 spec sheets do not offer any VDC limits. It just says to use the 14VDC PS14.
2)The LNRPXtra comes with a PS14 (14VDC) but the specs says 14-18VDC is OK
3) Others have reported improvements to Loconet reliability by using 18VDC across the board
4) I am in the very early set up stage and have been using Loconet for programing devices. No problems yet but if 18VDC offers an improvement for long term operations, I want to go with 18VDC now rather than deal with inconsistent operations when I load up Loconet with operations. However, I am not sure if 18VDC is OK with the UP5's and UR92.
Paul D
N scale Washita and Santa Fe RailroadSouthern Oklahoma circa late 70's
Yes. You can run all of those Digitrax items with 18VDC. LNRP and UR92 will not function properly with less than 14 volts. We found that out the hard way in 2008 on a mega sized NTRAK lauout using 12 volt supplies. This is why Digitrax raised their minimum voltage requirements to 14 Volts. Since the PS14 did not exist at time we used 15volt AC power supplies instead.
Anyhow, both items would be operating with voltage that is within the range recommended by Digitrax. Now the UP5 doesn't really operate on any voltage. It is just a set of jacks. The front jacks will power throttles that are plugged into it but the UP5 does not draw any power. Its track power led does but that only lights when connected to the rails. Since the rails could be on the highest O scale setting, 18 volts is fine . Throttles plugged into them will be OK as well.
Martin Myers
mfm37 ..............Now the UP5 doesn't really operate on any voltage. It is just a set of jacks. The front jacks will power throttles that are plugged into it but the UP5 does not draw any power. .................
..............Now the UP5 doesn't really operate on any voltage. It is just a set of jacks. The front jacks will power throttles that are plugged into it but the UP5 does not draw any power. .................
I don't understand this part of your comment. The UP5 has a circuit card and it must draw its power from somewhere. I have assumed it was from the sync lines in the Loconet originating at the command station. Although that is low power, it can run a limited run of UP5 and limited number of throttles. However, it quickly can become exausted thus the need for some power infusion along the way....typically by a PS14.
This ties to my question about adding power supplies along the Loconet line. Can I have a mix of PS14 (14VDC) and 18VDC supplies on the same Loconet? I don't know if that will iintroduce any problems.
PED mfm37 ..............Now the UP5 doesn't really operate on any voltage. It is just a set of jacks. The front jacks will power throttles that are plugged into it but the UP5 does not draw any power. ................. I don't understand this part of your comment. The UP5 has a circuit card and it must draw its power from somewhere. I have assumed it was from the sync lines in the Loconet originating at the command station. Although that is low power, it can run a limited run of UP5 and limited number of throttles. However, it quickly can become exausted thus the need for some power infusion along the way....typically by a PS14. This ties to my question about adding power supplies along the Loconet line. Can I have a mix of PS14 (14VDC) and 18VDC supplies on the same Loconet? I don't know if that will iintroduce any problems.
The UP5 is basically a passive LocoNet distribution device, with optional abilities to show track power status via the Status LED, and to distribute external power (if supplied) to the front throttle jacks. So the UP5 can certainly be used with no external power whatsoever.
But it sounds as if you're thinking that powering the UP5 will also power other devices on the LocoNet. That doesn't generally happen, with the exception of the throttles in the front jacks as mentioned above.
For other devices, you need to follow the Digitrax recommendations for that particular device or device family.
Generally speaking, you can power multiple devices of the same type from a single supply of the appropriate voltage and current rating, but unless you understand the intricacies of half-wave vs. full-wave rectification, you shouldn't power different device types from the same supply.
For example, I power 10 DS64's from a 12VDC, 2.1 amp supply. (Yes, 2.1 amps is overkill for 10 DS64's, but it's what I had available at the time.) OTOH, my PM42 (different device family) is powered by a separate 12VDC 500ma supply, and I supply my 7 UP5's with a 15VDC 1 amp supply since I don't bother with batteries in my tethered throttles.
OK. I understand the need to only share power supplies within a family. I do that. I also am not expecting the Loconet to supply power to any devices (DS64, PM42, etc) other than throttles. If I have a tethered throttle (no battery installed) on a long Loconet cord plugged directly into my DCS240 command station (no UP5 anywhere on Loconet), where is the throttle getting its power?
Fromt he Railsync lines. Which is why after more than a couple of throttles you need power to the UP5's, because the throttles without batteries will put too much of a load on Railsync and the voltage will drop (it is after all only going over thing telephone wire)
Something I always recommend - if powering multiple panels (and I see no reason why you can't do this), run a TWO WIRE DC power bus and tap off to 2.1mm plugs to plug in to the jack on the side of the UP. The "Digitrax" way is to daisy chain ONE wire from the hole on each UP5. Where do you think the other half of the circuit goes? Through the ground wire in the Loconet cable - same problem of thin wire, high current - lots of voltage drop. Less than just the Loconet cable for both sides, but if you plug power into the jack on each UP then both sides will be supplied with a full pwer bus. I'd also fuse each drop, you don't want an individual UP5 to be capable of drawing say 5 amps from a single large power supply that drives them all. A shorted pin or some other fault without some limit to the current each UP5 can draw could easily fry a throttle or cause other mischief.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy beat me to it - He was posting as I was still typing. But my answer would have been exactly the same, because that's how it works.
The only thing I will add is to mention the steering diodes on the UP5 board. They function to route the power from either the Railsync, the track power, or the externally-supplied power to those front throttle jacks without feeding it back into anything else.
So if you for example provide external power (and Randy has described the preferred method via the 2.1mm jack - Mine are daisy-chained using zip cord and 2.1mm plugs), the steering diodes prevent it from feeding back into the Railsync lines.
Thanks. With Randy's info plus the diode info, It all makes since to me now. I was concerned that a power supply on one UP5 might feedback into the Loconet and cause problems elsewhere on Loconet. I had planned to daisy chain power to UP5's using the Digitrax one wire method but Randy's info convinced me to use the power jack for power input.
There's another option, but it ends up suffering from the same voltage drop issues as relying on Railsync, because again the power flows through just those thing phone wires. It's shown here on the RRCirKits page:
http://www.rr-cirkits.com/Notebook/LocoNet.html
To do that, you have to have a branch of Loconet that connects ONLY panels for throttles - no devices that need Railsync can be on that branch, because instead of Railsync is has a fixed DC power supply. And the other branch can ONLY be boosters because the Loconet data is left off and it carries only Railsync and ground. Dick Bronson came up with this before the LNRP was introduced - and is more or less assuming DIY panels instead of actual UP5s. I would recommend the power bus with 2.1mm plugs over this option.