Atlas GP15 & 8-40CW Diesels

Sounds like you're looking at the old models, and the new ones?

There are some that are DC only. There are older models that have TMCC inside and are AC only. The newest can have DCC inside.

Engineer Joe,

According to the website this must be old as the hills as this doesn't have cab crew members. Would the MTH Z 1,000 power pack work with this?

Better avoid it as I want DCC eventually,DC for temporary.

Thanks,

Al Hummel

I'm not sure which one you're looking at? If it says TMCC, then yes, an AC pack is needed. Some came as DC only without a decoder.

 You can take any of them, and add a DCC decoder to them. I believe they all have a DC motor(s) inside.

http://www.atlaso.com/odash840b1.htm

lists both DC and with TMCC 2 rail for example.

The two rail scale GP15 is DC only.  An MRC Tech 2 will run it just fine.

There's two DC motors inside.  Unfortunately it runs a little fast.  I've been thinking of wiring the motors in series to slow it down, like a lot of folks do with Williams stuff, but haven't gotten around to it.

Rusty

OK. Went back to Atlas website & recorded the info they list,which is as follows.

3RAIL TMCC ITEM#0326-1. 3RAIL ITEM #0301-1.2RAIL DC ITEM #0351-1.So the key is hopefully being able to get the item no. It's listed as 2 rail so how could it be anything but DC,unless they added TMCC.

Thanks to all.

Al Hummel

Yes, TMCC was added to Atlas engines back some years in two rail. I believe Lionel said they wouldn't support it anymore. Atlas stopped installing it in their two rail. I'm just not sure of the exact time line. You don't see them come up for sale very often.

 I have some of the TMCC equipped Atlas engines. It's a shame they didn't sell better as they sound and run good to me. There were so few available that I went with DCS after trying DCC.

I guess this statement is where I got messed up too. I thought you were looking at older models. The statement about AC, only applies to the older TMCC equipped two rail models.

To make things more confusing, the newest models can have DCC onboard!

So it matters what year model or exact model number you are looking at exactly to know what to run it with.

There is a post on the old Atlas forum about this.  Jim Weaver states in that post that older 2-rail tmcc equipped locomotives could be run on DC by changing a switch, losing all command capabilities in the process.  He further states that later 2-rail locos did not have this capability as the electronics became too complex.

I have no idea when the change was made or which models it affects.  I know that at some point Atlas also offered 2-rail locos with QSI dcc.  So you would need to know the specific model number for the loco you are interested in.

Jim

Engineer-Joe,

The number on the loco is,0351-1 which according to Atlas' spec's is 2 rail DC. What the original owner may have added,I don't know. i'm pretty confused on all these systems of control.Lol

Thank you for your help.

Al Hummel

The model #0351-1 is a Chessie System RD#1508 2 rail DC, TMCC was only offered in the Tman line at that time on 3 rail models the GE 8-40B was available with TMCC in a 2 rail version although not noted on most 2 rail TMCC models the RS-1 and the SW1200 RS copy states AC/DC operation* [DC operation requires Power- Inverter sold separately] hope this helps.

I bought a DCS System with TMCC & was reading on the box today-it says 24VDC,plusfor AC it has,o.22VAC,190VA&12.0AMP It's starting to sound like it'll run DC,AC,& engines in 2rail equipped with TMCC? Am I wrong? ( According to the wife I'm wrong on most things).

Al Hummel

I believe the marketing concept of TMCC 2 rail was to encourage 3 railers  to try 2 rail operation with there existing TMCC control equiptment.

There was more to it than that. DCC systems for O scale at the time were expensive, while TMCC was inexpensive and simple (1 wire to common) to implement, although it required an AC track power source. To improve the signal, placing a .1uF capacitor between the common (ground) rail and the hot rail would allow the TMCC signal to jump onto both rails without shorting the track voltage (frequency too low to jump the capacitor).

For some reason, people equate the number of rails with the control system. The rails are merely a delivery mechanism (outside of keeping your trains off the ground). The fact is, that you can use any system with any number of rails if you keep track of what's hot and what's not.

Well here goes.

TMCC works well on two rail by itself. I had trouble with it interfering with DCS at the same time on the same rails. I'm sure it was just me. I could get it to work but with only one TMCC 2 rail Atlas engine, why would I bother? At the time, I couldn't find any more available. With MTH into S scale now, I'm sure they get it to work together.

 You can't mix DC and AC engines. Well you could, but it gets complicated. Maybe using an AC transformer for supply and into the TIU, outputs fixed 1 and 2 would be AC, with full bridge rectifiers on the variable channels 1 and 2 outputs (dc) could run them at the same time on different tracks. Is that what you were asking?

 The TIU can be used with DC only on the two fixed channels.

 If you want to run TMCC equipped, you would use AC. Engines without decoders would be just DC. MTH's can be run with either. I've heard newer TMCC and Legacy can run on DC but I don't know the distinction in models. Lionel doesn't support any O scale two rail anymore so there's no new ones (legacy) out there.

I'd edit that one a third time but it keeps getting worse. I'm just spitting out stuff.

Rusty,

I called Atlas & they told me I MUST run the GP15s on variable DC not Straight DC or the diesel will race out of control,which proved correct.

Now for MTH 2 rail diesels do I have to do the same,use variable DC? If not I'm lost on control systems. I don't know what to buy,as all MTH control systems seem to be pointed to AC power.

On a similar subject,how much should a modeler pay for used MTH 2 rail GP38-2's?

Thank you,

Al Hummel

Extreme LOLsome very good information though.