# Connecting Zimo MX645 to GWire receiver



## Beddhist (Dec 17, 2013)

Hi,

After several days of fruitless googling and reading manuals I have come here to ask my questions. Hopefully, some experts can point me in the right direction.

I have a Bachmann Davenport and a railtruck, a few metres of track and a few wagons. All beginnings are small. Since I don't have any electrical equipment I figure I will go for what I think will work best for me. (I'm in NZ and I haven't found anybody in the area with a G scale setup, so there isn't anywhere for me to have a look at equipment.)

I have listened to recordings of the sound for the Davenport from Zimo and that's why I want a Zimo decoder in it. I also want wireless and batteries. There seem to be two options: Airwire or Gwire.

It seems that most folks in the know prefer the NCE Gwire cab. The instructions for the GWire receiver are not completely clear to me. For one thing, I can't see in their diagrams for a generic decoder how the battery + is connected to the decoder. Do I wire that into the "common +" on the Zimo (blue wire)? The Zimo has a GND connector, but is that the "decoder common ground" in the GWire diagrams? The Zimo also has a +5V supply on the back. I wonder whether that could be used to power the GWire, but I can't find out how much current that will draw. The Zimo can supply 0.2A.

Can this combo be made to work without electronic wizardry?

The Airwire Convrtr looks like it's a very simple one to connect, but I am led to believe that the NCE throttle will not let me program the decoder, so to be safe I would have to use the T5000 with that.

I would be grateful for any advice.

Thanks,
Peter.

PS:
I asked both CVP and QSI. CVP seemed surprised that the NCE GWire cab might work with their Convrtr, but offered no further help. QSI said they didn't make the GWire throttle, so not their problem and they couldn't advise on how to connect a non-QSI decoder. (Hmmm, on their web page it says "Developed in cooperation with QSI Solutions." and "If you have a special request we can do the wiring for you or send the instructions", so I expected a little more from them...


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## East Broad Top (Dec 29, 2007)

Short answer, no. The output of the G-wire receiver is not a bi-polar square wave DCC signal, so it's not a straightforward installation. As you've discovered, figuring out how to hook the output from the G-wire to various decoders isn't exactly clear, nor is it something I've found either QSI or the individual decoder manufacturers have given any follow-up to. I've asked QSI similar questions, and got pretty much the same answer you did. I think they're relying on the adventurous spirit of modelers who don't mind experimenting and potentially turning $300 worth of electronics into not-very-effective paperweights. Yeah, that ain't gonna be me. 

In terms of the comparing the controllers themselves, I preferred the NCE throttle compared to the _earlier_ generation Airwire throttles because the previous Airwire throttles lacked any kind of informative display to show speed or other features. The T-5000's display "fixes" all of the issues I had with the older throttles, and I like the menu-driven programming on the T-5000--a definite improvement over the old way. Given the choice between the NCE and T-5000, it's much more of a toss-up. The advantages of the NCE controller really only come into play with the QSI decoders, so if you want to use the Zimo, the T-5000 is probably the better option. 

For what you're trying to do, I think the Airwire T-5000 and Convertr controling the Zimo receiver is a great way to go. I've got the Convertr/Tsunami combination in my ex-RGS Goose #6. Given what you mentioned in your other post, I think you'll find the Airwire system gives you a bit more flexibility in terms of what combinations you can use. With the Airwire transmitter, you can use the Convertr with any generic DCC decoder (so long as it draws less than 2.5 amps), the G3 motor board and Phoenix sound or any other DCC or non-DCC sound board, or the QSI with the G-wire receiver. If, down the road, you want to get a second transmitter, then you can get the NCE transmitter. 

Later, 

K


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## Beddhist (Dec 17, 2013)

Thank you very much for this clear explanation. I really appreciate that you took the time for a newbie. 

The way forward is now clear and I shall order the Airwire and Zimo's soon. 

Kind regards and have a haapy Xmas, 
Peter.


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## steam5 (Jun 22, 2008)

Peter 

I tried similar a couple of years back. Just gave up. Emailed manufactures and got nothing, they even advertised certain things, but couldn't tell me how... 

Alan


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## Dan Pierce (Jan 2, 2008)

What is the stall current of the Davenport? The MX645 may not handle that engine under a heavy load if it is the largescale engine. 
Rail truck would not be a problem with the MX645.


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## Beddhist (Dec 17, 2013)

According to this: http://www.girr.org/girr/tips/tips10/davenport_tips.html it's 1.5A. The Davenport actually has an 8-pin NMRA plug for an HO decoder. According to the Zimo web site this is the decoder to use. Here it is in action: http://www.youtube.com/watch?v=rJjNry70mZM


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## StanleyAmes (Jan 3, 2008)

Posted By East Broad Top on 22 Dec 2013 12:27 PM 
Short answer, no. The output of the G-wire receiver is not a bi-polar square wave DCC signal, so it's not a straightforward installation. As you've discovered, figuring out how to hook the output from the G-wire to various decoders isn't exactly clear, nor is it something I've found either QSI or the individual decoder manufacturers have given any follow-up to. I've asked QSI similar questions, and got pretty much the same answer you did. I think they're relying on the adventurous spirit of modelers who don't mind experimenting and potentially turning $300 worth of electronics into not-very-effective paperweights. Yeah, that ain't gonna be me. 


Later, 

K 
Longer answer is it depends. I routinely use Lenz decoders with a G-Wire receiver with no problems. Installation is relatively easy. The signal output from the G-wire radio receiver is indeed normal DCC (tested with a scope) with a few exceptions. The most notable is that the signal is 5V while many decoders require a signal of greater voltage. The other notable exception is that with normal DCC the signal and power are the same and with G-Witre the signal and power are seperate.

With a Lenz Gold decoder I hook up the Gwire output to the decoder's track input and a +- power source to the decoders +- inputs. You also need to power the G wire with +5 volts which is easiest to du using a voltage regulator.

I have several locomotives using this coonfiguration and switch between Gwire and normal DCC depending where the locomotive is being used. Several years back provisions for low voltage DCC signals were being discussed as a general DCC topic but the discussions died when the committee died. While I know this works with Lenz Gold decoders I also know this configuration does not work with all decoders in the market. I have not personally tried it with Zimo decoders.

Stan


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## East Broad Top (Dec 29, 2007)

Thanks for clarifying, Stan. That's what I figured to be the case, but have never put it on a scope to check it. Since it's not just a matter of attaching those two wires to the "Track DCC" in on a decoder to be able to run a locomotive, I figured the simplification fit the purposes of our discussion here. 

With a Lenz Gold decoder I hook up the Gwire output to the decoder's track input and a +- power source to the decoders +- inputs. 
Aye, there's the rub. Finding the decoder's "+" and "-" inputs isn't exactly cut-and-dry, nor necessarily easily soldered/attached to from the few diagrams I _have_ seen. That's what I was trying to find out myself from QSI--how easy it would be to find that on a generic decoder, but QSI didn't have an answer. Can you post a wiring diagram of how you did that? I'd love to see a web page that shows which decoders people _have_ successfully hooked up to the G-wire receiver, and how they wired them. I think it would open up a whole new range of possibilities. 

Later, 

K


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## StanleyAmes (Jan 3, 2008)

Posted By East Broad Top on 23 Dec 2013 10:03 AM 
Thanks for clarifying, Stan. That's what I figured to be the case, but have never put it on a scope to check it. Since it's not just a matter of attaching those two wires to the "Track DCC" in on a decoder to be able to run a locomotive, I figured the simplification fit the purposes of our discussion here. 

With a Lenz Gold decoder I hook up the Gwire output to the decoder's track input and a +- power source to the decoders +- inputs. 
Aye, there's the rub. Finding the decoder's "+" and "-" inputs isn't exactly cut-and-dry, nor necessarily easily soldered/attached to from the few diagrams I _have_ seen. That's what I was trying to find out myself from QSI--how easy it would be to find that on a generic decoder, but QSI didn't have an answer. Can you post a wiring diagram of how you did that? I'd love to see a web page that shows which decoders people _have_ successfully hooked up to the G-wire receiver, and how they wired them. I think it would open up a whole new range of possibilities. 

Later, 

K 
Kevin

QSI Solutions has this documented on its www site at the bottom of the page

http://www.qsisolutions.com/products/q-gwire.html

Some manufacturers have both the + and - connections clearly identified with non solder connections, others have it documented but require soldering and others really do not support this connection. Depends on the manufacturer and decoder. For example the Lenz Gold maxi decoders have a screw terminal assigned for this purpose. Thier HO decoders have a solder pad.

The AirWire/Gwire signal has a timing that is close to the DCC standards but does not conform. Still it is in range that many decoders can work with. 
The signal strength may or may not be sufficient for the decoder to function. For example works with Lenz Gold decoders, does not work with Phoenix P5s.

The lenz Gold decoders have an advantage to all others in the market as they can read the DCC signal with no track connection so they have no problems at all with a low amplitude signals.

I have not tested this with Zimp decoders.

Hope that helps

Stan


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## East Broad Top (Dec 29, 2007)

Yeah, those are the drawings I've seen. There's also this page: 

http://www.qsisolutions.com/news/09/gwire-receiver-090309.html 

The illustration at the bottom show it can be done in generic terms, but when I asked them for specifics, they had none to offer. None of this is a slam on them--they designed the G-wire to work specifically with their decoder. I wouldn't expect them to spearhead applications where it can be used with their competitions' boards. I'm surprised Zimo, ESU, etc., haven't taken a look at the G-wire receiver to see if they can make their boards work with it. Seems to me it would increase their potential market by quite a bit. Surely they've got some spare boards sitting around to experiment with. 

(I know... don't call them "Shirley.") 

Later, 

K


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## Dan Pierce (Jan 2, 2008)

The MX645 does have a blue wire for common power and there is a ground. Do not use the storage capacitor positive as this is not V+


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## Beddhist (Dec 17, 2013)

Hi folks, 

Thanks for all this valuable info. Have a nice holiday. 

Kind regards, 
Peter.


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