Using an n scale decoder in HO

[Southern1970]

Hi all, I have a spare loksound 73199 decoder and was wondering about hardwiring it into a HO Proto sw9/1200, or a Walthers trainline GP-15.  I’ve read that the loksound 58823 has 1.5 amps, but the 73199 only has 0.75 amps.  Would this be enough in either HO locomotive or should I just wait to save up for the 58823?

[peteski]

Hi all, I have a spare loksound 73199 decoder and was wondering about hardwiring it into a HO Proto sw9/1200, or a Walthers trainline GP-15.  I’ve read that the loksound 58823 has 1.5 amps, but the 73199 only has 0.75 amps.  Would this be enough in either HO locomotive or should I just wait to save up for the 58823?

As you mentioned, the deciding factor as to what scale model a DCC decoder can be used in is the motor's current rating.  I'm in N scale and I don't know what are the specs for your locomotive. The current rating for the H0 motor in your locos might be specified on the locos box insert or on the documentation included with the loco.  Older H0 locos had motors that needed a lot of current, but many newer models have more efficient motors.  If the motor is rated for less than 0.75A then you could use the 73199 decoder.

[ednadolski]

I think you should be able to test the stall current draw of the motor with a DC ammeter.   Just to speak for myself tho, I would prefer to wait for the fully rated hardware.

Ed

[jdcolombo]

FWIW:

For the past three years, I have been converting a friend's HO-scale diesel (and steam) fleet to ESU LokSound decoders.  The diesels are from a wide range of manufacturers: Atlas, Walthers, LifeLike, BLI, Athearn, etc.  I have used wired LokSound micro decoders in literally dozens (maybe 100 total) of these conversions because of space limitations in the old chassis designs with zero problems.  Early in this process, I tested several of these locos with an ammeter, and found that modern HO scale motors are just as efficient as N scale motors and in general have only slightly larger current draws under load (below 1/2 amp).  Adding to this is the fact that ESU's HO board decoders are really nothing more than an ESU micro plugged in to a board that fits the HO chassis, and you have a pretty good indication that the ESU micro will handle nearly all modern HO motors.  Maybe I wouldn't do this with a 1960's Athearn blue-box open-frame motor, but everything else has worked perfectly.

That said, testing current draw with an ammeter is always a good idea.  But a lot of "maximum current draw" specifications are done by stalling the locomotive.  In the real world, a loco doesn't stall under load - its wheels slip.  So the maximum current at stall is, IMHO, an unhelpful guide for decoder selection (plus, ESU decoders have built-in fail-safes that shut down the decoder in over-current or overheating situations).  Instead, a more helpful guide is to load the engine until its wheels slip.  This will tell you whether the maximum current draw in real-world situations exceeds the .75 amp rating of a LokSound micro.

But I can tell you that none of the conversions I have done have experienced any operational problem resulting from current draw.  They all run like Swiss watches, almost always far better than they did in stock form.

John C.

[Jim Starbuck]

Again, like John FWIW,

I model primarily N scale but am also involved with an HO club layout. My HO engines are Atlas, Proto and Walters switchers into which I’ve installed Loksound v5 Micros without issue. I also have an old rescue dog Athern SW7 which was given to me on one of my first visits to the club to take home and see if I could do anything with it. After remounting the stock motor it got a Loksound v5 Micro because that’s what I had on hand. It runs just fine and sounds very good.
I have a Proto SD7 that I plugged a Lokpilot V5 Micro (the tiny one) into again, because that’s what I had on hand with an 8 pin plug. This engine runs very well and at last weekend’s open house ran for about three hours pulling a 15 car train up the 2% 6 loop helix several times with zero problems.
Whatever you choose to install is entirely up to you but all of my HO locomotives are running on smaller Loksound and Lokpilot decoders without any problems or showing any signs of overload. As a caveat the SD7 is the largest loco in the fleet with the rest being switchers so 10-12 car trains are common.The engines will pull more but that’s just the way I run them so I’m not sure what it takes to stall them. Like John pointed out, they lose traction before the motor stalls.

[peteski]

. . .
The engines will pull more but that’s just the way I run them so I’m not sure what it takes to stall them. Like John pointed out, they lose traction before the motor stalls.

During normal operations there is no possible way to stall the loco's wheels (and motor).  Only way to stall it is to physically jam the drivers (which does not occur during normal operations).  Plus the stall current is also measured with full 12V applied to the motor. That is another scenario which rarely occurs during normal operation.  At voltages less than 12V the stall current will be proportionally lower.

[oakcreekco]

It's been a while, but I  installed numerous Digitrax (non plug and play, no sound) N scale decoders in HO Atlas (Kato build) locos.

No issues, excellent running, some nice lighting fx used too.

Match ratings and with a good drive, operate away.

[wvgca]

sure, why not ??
be sure to leave a little room so you aren't really close to the full amperage draw of the locomotive  ..

[jdcolombo]

sure, why not ??
be sure to leave a little room so you aren't really close to the full amperage draw of the locomotive  ..

That's the problem - what is the "full amperage draw" of the locomotive?  My initial message above indicates that stall current is NOT the correct measure of this, and yet that's the specification you'll usually see (if any) in locomotive tests.  My own measurements indicate that modern HO scale diesels (and steam) do not draw over 1/2 amp under full load with the wheels slipping.  And remember that in normal operations, that won't happen, because you'll offload some cars or attach a helper.  And all that in turn means that any decoder with a .75 amp continuous rating (nearly all N-scale sized ones) should be just dandy for HO installations.

John C.

[Southern1970]

Thanks everyone for your input. Really appreciate the advice.

 I will try it to hardwire the loksound 73199 into one of the HO locomotives, next chance I get.

Cheers
Allan

[woodone]

call me old school, But I still lock the motor and test for the current draw. Whenever I work on an HO locomotive.

[turbowhiz]

Fitting the 73199 to at least the proto SW (I can't speak to the GP15, but this applies to HO models in general) will be MUCH more difficult then need be; There are way better "fit" options, and although a hardwire install is required regardless (at least in early runs), that 73199 won't fit well at all. Typical HO applications are "shorter and wider" rather then being "long and narrow" like the N scale diesel board replacement style decoders. In general, N scale "long skinny" style decoders don't have much utility in HO scale applications just because of the shape, not because of current draw. The proto SW had a screwed in block in the frame that you removed for decoder clearance, in the front of the loco. The cab is detailed, so you loose that end, and the rest is tight for as much weight as possible. To get the 73199 you would probably need to mill the frame, and I figure there is a good change you still end up with the decoder intruding in the cab, never less finding speaker space. And those models get almost too light with the factory "decoder block" frame section removed, so yeah....

(all of this is from memory, so I might have some details wrong.... But I'm pretty sure this is how they go)

You would be much better served with a 58823 or something along those lines.

Testing current draw is always a good call, but if your Proto SW is isn't wildly out of spec I'm sure you're good. I was installing N scale decoders in those locos ~20 years ago when they first showed up on the market.

[JeffB]

Good question and it comes at the perfect time...

I've been working on a few Sn2 locomotives of late (S scale, using HOn3 track/wheelsets).  One of the locomotives is a 2-6-2 that I'd like to add sound to, but I want to put the decoder and speaker in the cab of the locomotive.  (so I don't need to run a bunch of wires in between the tender and locomotive).

I plan on powering it with a 10mm x 20mm coreless motor, (with sufficient gear reduction to make up for the motor's small size).  Being a coreless motor, the current draw is very low (<100ma), with a low stall current to match.  (I plan on using the same motor in the 0-4-4 Forney as well)

For (lack of) space reasons, I'd like to use a ESU Loksound micro decoder.  Going by the amp rating in the specs, it seems as though I should be OK as the stall current of the motor I plan on using is well below the max amp rating of the Loksound micros.

So this is a timely question...

JB