Newbie Question - DCC and LGB

JimmyB

JimmyB

Phase 1 complete, roll on Phase 2
23 Feb 2018
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I don't mean to sound patronising, this is how I started with Hornby OO digital starter set many years ago.
Dave, not patronizing, very helpful, I assume this was the Zero!
 
idlemarvel

idlemarvel

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13 Jul 2015
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Dave, not patronizing, very helpful, I assume this was the Zero!
No not the Zero, not that far back, pukka DCC. I didn't have the spare time or cash to play with trains until the kids left home and I retired from full time work, about 13 years ago. I started with OO gauge and Hornby were the only company to sell a complete DCC system including trains, track, transformer, command station/controller and PC software to control trains points and signals. The software was a bit clunky, and support even more so, but it worked most of the time (Hornby RailMaster) :)
 
R

robboz4

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6 Dec 2018
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I placed an order for this Pololu one as I need the higher voltage for the LGB track. The regular shield is only 12volt. It should arrive tomorrow so stay tuned for the next Q&A session.
 
John S

John S

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5 Nov 2017
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Exeter, Devon, UK
I placed an order for this Pololu one as I need the higher voltage for the LGB track. The regular shield is only 12volt. It should arrive tomorrow so stay tuned for the next Q&A session.
Er! Nope.... the 12V limit ONLY applies for the supply to the UNO, that is the MAX INPUT the internal voltage regulator can handle.

Re post #43 and post #54, by cutting the trace VIN on the underside, breaks the link between the Motor Shield and the UNO, the UNO is now powered separately by a 5V supply or by a supply not exceeding 12V.

The Shield has a seperate DC IN, it has the capability to handle a MAX INPUT voltage of 24V, more than enough for an LGB engine, within the the 2 Amp limit set by the controller IC.

There is a high power version solution that can handle 43 Amps* and 40 volts, several people on this forum are using this option very successfully.

*Need to take that figure with a pinch of salt, realistically somewhere between 5 Amps and 15 Amps top......................

Both of the above are considerably cheaper than the Pololu choice.
 
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robboz4

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6 Dec 2018
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OK! After soldering the pins and terminals, and creating jumpers plus recompiling DCC++ for the Arduino, to use the Pololu board, I'm only slightly better off. If I try to identify the engine on the track with power on AND the engine noise is idling, the sound gets interrupted but I always get the 308 error. So now I'm baffled. I did manage to use the earlier configured switches to try sounds on/off etc, but they fail now.

Also another anomaly is that the analog LGB power source. No matter how I wire the track (main or programming) when I apply power from the software (JMRI or DCC Controlller) the alternate track turns on ( the LED lights on the Pololu board.) - the one without the track connected. or engine. if I turn down the analog control to zero and then back up, both tracks turn on and the engine powers up. But I always get errors trying the JMRi program. And I can confirm on my system there is a bug in JMRI where if you try to access a function on an engine and it fails, JMRI loops on that last DCC++ command for ever. Even if you power off the track. A reboot fixes it. Commands do seem to go through, like power on/off but that last command is just being resent.

So to answer an earlier question about diving in the deep end - sure. It's only a small micro running a protocol it shouldn't be that difficult for me. I have quite a few home-brew devices happily running that i have built. But it's alway good to ask experts who have blazed a trail!

So off to read more and probably buy a power supply. I might try one of the switching ones you see on Amazon. They seem cheaper than the LGB one.

Cheers ( definitely need a beer!)


Dave
 
ntpntpntp

ntpntpntp

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24 Oct 2009
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If I try to identify the engine on the track with power on AND the engine noise is idling, the sound gets interrupted but I always get the 308 error.
Dave
That doesn't sound right. To "identify" a loco by reading CV values you need to be using a programming track in service programming mode - the track power is never on continuously on a programming track.
 
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robboz4

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Well JMRI says I was in service/programing mode. I had the track connected to the programing track not the main track and the engine on that track. I don't have two tracks only one. According to the schematic the M2A and M2B should be the programming track.
So lets' get back to basics of working with no engines.

I have and Arduino with DCC++ code connected to a Pololu MC 33926 Motor shield. I'm powering it from an LGB 50081 24volts @1 amp turned up full.
I have one track connected to the programming track.
I have 24Volts DC input - measured.
I turn on the track power from the software and both sets of power LEDs come on the motor shield. I have ~53volts AC on each output. I'm using a old digital voltmeter set to AC to measure. So that indicates power is on both tracks. I din't both with an engine for this test.

I then downloaded the Pololu demo code just to test out the Arduino and board. It failed. So looks like I may have a bad board. Will try again one the replacement arrives...

Sorry the thread is getting long. Perhaps we should terminate it and I'll start another when/if I have further issues with a new board.
 
Greg Elmassian

Greg Elmassian

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8 Mar 2014
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So you are saying that the 53 volts ac is appearing on the programming track? If so, something wrong, no matter what JMRI is telling you, refer to last sentence in post 66.

Hope you solve it, sounds like you just isolated a hardware problem.

Greg
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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Hope you solve it, sounds like you just isolated a hardware problem.
I too how you solve it...

I just hope the '53v' figure is an anomaly, else you may have damaged the decoder as well? :(