[SPROGman]

QUOTE (Doug @ 25 Jul 2007, 15:07) <{POST_SNAPBACK}>I have just tested - with the long wave radio - the effect of removing the capacitor.

Note, I have never had interference problems before on TV and radios in the house due to the trains in the garage. I do listen to BBC on the Internet in the garage, so the long wave radio has been gathering dust over the years.

I placed the radio right next to the terminus at my turntable. I tuned in (BBC Radio 4) and got quite a good amount of static when I powered up the DCC system. I ran a Hornby steam loco that had a capacitor at the motor terminals on address #0. A little more static and whining on the radio. I snipped the capacitor and there was a considerable drop in static. I wonder why?
The subject is complicated enough, without bringing DCC address 0 into the equation ;-) Any loco with capacitors fitted for EMC will only have been tested on DC. To see the difference between cap/no cap you need to test with a DC controller.
QUOTE I added a Lenz Gold decoder and the static increased a bit. Not quite as much as without the decoder. Reconnecting the capacitor whilst the decoder was in place made no difference to the static.
The decoders PWM motor drive is drawing current at a different frequency from and asynchronously to the DCC waveform (ie not in time with it). As you add more chipped locos (each slightly out of phase with the others, and drawing different currents) you end up with quite a complex current waveform which leads to more (or at the very least different spectrum) noise. Try adding more chipped locos and operating them at different speeds with different loads.

I would like to know what constitutes a representative layout for the purposes of EMC approval of a DCC booster. Anyone?

Andrew

 

[SPROGman]

QUOTE (Doug @ 2 Aug 2007, 16:30) <{POST_SNAPBACK}>Compliant, Conformant & Compatible. 3 words designed to confuse the best of us. What chance do we have when the spin-doctors use them sans-souci.
The only term that actually has any defined meaning wrt NMRA DCC is conformance. Equipment that has been submitted to the NMRA and passed is awarded a comformance warrant and is allowed to carry the "(american) football" logo.

The terms compliant and compatible mean whatever they mean, as defined by whoever is using them.

Andrew

 

[SPROGman]

QUOTE (Doug @ 6 Aug 2007, 14:10) <{POST_SNAPBACK}>Generics/Sagentia (Cambridge) was involved in developing the Digital Scalextric technology http://www.sagentia.com/Resources/Case%20s...scalextric.aspx

I'm not sure if they were involved in the Digital train products.

If not them, who else?
I think this link was posted on MRF a while back:

http://www.britishdesign.co.uk/index.php?p...project_id=1927

clicking through the actual company involved:

http://www.productresolutions.com/whatweve...ct/product4.htm

"Here we teamed up with Hornby to design a ground breaking digital control product range known as DCC Systems". No comment.

Andrew

 

[SPROGman]

QUOTE (Richard Johnson @ 10 Aug 2007, 09:19) <{POST_SNAPBACK}>No problems - hope we get to the bottom of it eventually.

If you can find one lying around an old laptop power supply is a great option for a small layout: 3 amps at appx 18vdc and well regulated.... Much more stable than any AC supply will ever be!

Richard
Agreed wholeheartedly with that. I can never understand why anyone would pay nearly £50 for a nicely packaged Lenz transformer when you can get a switch mode power supply for half that or less from somewhere like Rapid Electronics here in the UK.

Virtually anything [1] (and I would bet all DCC equipment) that works on AC will work on DC but you need to calculate the DC voltage required as approx 1.4*AC volts to account for the AC being quoted as an RMS figure.

Andrew

[1] The only things that will not work are things with an internal transformer or anything that needs the 50Hz frequency as a timebase.

 

[SPROGman]

QUOTE (Gary @ 20 Aug 2007, 10:00) <{POST_SNAPBACK}>All I can say is that its an unusual law that does not provide for giving a manufacturer or consumer protection or requiring that a level of protection is maintained at all times in the event of modifications made and/or instructions issued by a third party. Gordon H in his analysis above claims that for technical reasons you are going to provide a lower level of EMC protection if you rely purely on a decoder. Unless of course he is wrong.

And that it is entirely wrong of 30+ members of the NMRA to agree that they do not instruct customers to remove capacitors when it is patently obvious that they do! Unless of course ZTC have missinformed the public.

Happy modelling
Gary
Please provide a reference for this agreement by 30+ members of the NMRA. It does not appear to be minuted in the DCC working group minutes http://www.nmra.org/standards/DCC/Minutes/minutes.html and, in any case, I doubt that 30+ members of the NMRA would all be DCC manufacturers. Many members of the WG are not manufacturers.

Andrew

PS There's no such thing as the DTI police. CE regulations are enforced by Trading Standards. Radio and TV interference is investigated by Ofcom, and only following a complaint from someone experiencing interference. I defy you to provide a reference to a documented case of anyone in the UK having action taken against them for causing interference with a model railway.