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Just another modeller
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QUOTE (ChrisE @ 20 Oct 2008, 15:57) <{POST_SNAPBACK}>I have an indoor G scale layout that I want to DCC equip. I need to be able to operate the railway from a number of locations & I do not want trailing wires. Whilst G Scale can use up to 20v it currently runs at perfectly adequate speed/power from an old H&M Clipper which has "controlled output 12v DC" and which at full power & with my largest loco running at full speed gives an actual track voltage of 14.5v. The largest loco draws 1.25 amp, at startup with a heavy load, if I bang the throttle open & 0.75 amps when steady running at full speed - which I never normally use. The power of the Clipper at 1.5amps appears adequate.

The most economical transmitter type DCC system appears to be the Dynamis. I have a number of questions about it which hopefully someone can answer.

1. What is the actual measured track voltage of a Dynamis system when under load?

2. What is the voltage loss through a DCC loco decoder?

3. I note that I can't read the decoder with the Dynamis. Why does this matter? How do I get round it?

4. What is the user experience of the Dynamis system now that it has been around for a while?

5. Is there a better alternative without spending a lot more money given that I want wireless remote control.

Thank you.

Chris, your line "I need to be able to operate the railway from a number of locations" says do not use the Dynamis - it needs to be in direct line of sight of the IR receiver and no more than about 20 degrees off axis to communicate properly - if it loses contact, then it will shut down track power.

Personally I think a wired system and several layout panels to plug in a would be a thousand times better than a dynamis "running reliability" wise if you intend to move around much.....

Being able to read CVs is actually important if you want the best from DCC - those who can't do it will never understand what they are missing. You could use a 3rd party product like the SPROG and your computer to read CV's, but then add the cost of Sprog+dynamis and you are well above the base dynamis price and still compromised for reliable wireless communication.

To be honest if your budget is limited then the answer is there is NO 100% cost effective answer!

The best DCC radio system by a country mile is made by NCE, but you will have to buy it direct from the US as its not approved for a UK retailer to sell it - no problem for a private buyer to buy and use, but a big fine for a retailer to buy and sell within EU!

The next nearest may be the Lenz Set 100 + the Lenz XPA which will let you use any DECT portable phone as a controller - but then you are again so close to a directly imported NCE radio system I wonder at the compromise...

As to your other questions re voltages, track voltage varies by brand but the output voltage of every DCC system will run your G scale just fine. You will get a drop of appx 1 volt between rail voltage and motor...

Richard
 

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Just another modeller
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QUOTE (upnick @ 20 Oct 2008, 19:47) <{POST_SNAPBACK}>A word of warning with any illegal frequency system if it should conflict with the emergency services the equipment WILL be confiscated and destroyed and could lead to a fine to the user of it.

***Nick, Brian: Sorry but that is a little extreme: You could have the unit in the same room as a medical unit and not interfere - or in the same tin box for that matter!

Before such comments you should understand what is being talked about:

For a start, read the specs for the NCE radio power... 0.00035 of a watt from memory (350µ watts). Despite this with the current software it has got great range for train operation and it is faultless in poeration.

Do you really think I would make a recommendation that could compromise a list member - there are hundreds of many brands - including NCE, Easy DCC and Digitrax radio systems working quite happily in UK every day, and the courts aren't full of recalcritant railway modellers.

Digital radio is nothing like older analog radio issues. frequencies are super tightly controlled as is the content of the digital signals.

Anyway.... actually its NOT illegal for a consumer to import and use use anyway - it is merely illegal to cause inconvenience or conflict problems for others including neighbours, something an average power tools radiated energy and an overloud car stereo system does far more than such a system ever could.... and something an average mobile phone does on almost the same band on a grand scale compared to an orchestra of any 1000 + Radio based DCC systems (an average mobiles transmitted RF power peaks at better than 10,000 times the output of an NCE radio system).

Come to think of it, a standard DC locomotive, a portable CD player and an Ipod all radiate with far, far more energy too!!

Talking about different spectrum allocations in different countries doesn't work either:

FYI the spectrum allocations are pretty well the same here in AU as they are in UK, especially in that band area, and the CE regulations are mirrored and the NCE passes with no problem.... in fact the officer from the spectrum management who did a routine audit on my CE paperwork a year or two ago made the comment that given the power, the purpose it is designed for etc it was a narrow judgement call whether it actually needed Any approval for the radio part of the system at all!

He was more interested (quite correctly as that is not as tightly controlled in any DCC unit) in the possible radiation from the command bus and higher power booster circuitry in fact!

The ONLY reason its not fully licensed for UK is the excessive cost of obtaining EU approvals, which is ridiculously high compared with using fully approved CE laboratories in other parts of the world.

Richard
 

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Just another modeller
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QUOTE (ChrisE @ 20 Oct 2008, 17:30) <{POST_SNAPBACK}>I doubt it. The loco that I referred to above is a two driven bogie/ motor diesel and has a stall current of 2.5 amps plus. That leads me to think that even with one motor it would be very marginal with a 00 designed chip. My single motor locos run at nearly the same current. I await being told that I am wrong but I think most OO loco decoders are unhappy at anything above 1 amp.

***With a slip current of 1.25 and a running current of 0.75 you could use a standard TCS chip (1.3 amp continuous motor drive, 2 amp max) quite reliably however a full stall may cause grief. For single motor G scale ex europe a standard TCS chip will be fine, but I'd not try an esu, lenz, bachmann or hornby.

For 2 motor drives 2 standard chips are fine, one pwer motor. Some adjustment of back emf to have it turn off after initial slow speed starts - say at about speed step 8, would stop any back EMF interaction at running speeds but preserve speed step one slow running quality.

There IS an advantage in using a V3 LokPilot XL though - it is designed for higher current large scale and it has a full stay alive built in so no stalling on dirty track or dead frogs ever - its a really nice decoder but a little expensive, and certainly the one I install into G scale often by choice.

Richard
 
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