DDC CV question

[Anonymous]

There is an article in the current 'Model Railroader' about installing a Soundtaxx card in a Bachmann Consolidation. The author references setting the chuff rate with the loco operating on the 6th step of 28 steps.

My command station's default is set for 128 speed steps. Assuming I don't want to change that, if I want to duplicate the author's settings, do I perform a mathematical proportion calculation (approximately speed step 27 out of 128) or is there something more to it?

[jnichols]

First off, I'm not sure which decoder the article was referring to, so I'm not sure how to help, but I'm guessing it's the plug and play DSD100LC series so here goes...

The concept is to set the chuff rate for the locomotive at about 15% of it's speed range, this will yield a more usable rate from stopped to full throttle. Without BEMF, there is no way for the decoder and drivers to stay synced up. If you want a dead on 4 chuffs per revolution, you will need to install a cam setup with that decoder...

Now if it's not the PnP decoder, ignore my post... [:D]

Jeff

[selector]

For what it's worth, my CV settings for chuff with a 100LC never seem to be consistent from one power-up to another. I even get different chuff rates for reverse over going forward.

Mine is set at 128 speed steps, and my CV setting for the P2K 0-6-0 is around 47.

[JohnT14808]

I have another question:

In shopping around for decoders, I am finding lots of sellers. I need just a basic decoder to handle speed, forward/reverse and lights. Nothing fancy. My question:

If I purchase an off brand decoder, does CV2 on one brand equal CV 2 on other brands? I have a Digitrax programming guide, and am planning on using it to program the decoder I purchase. Can I do this using Digitrax CV values for the CVs that I want to set on this off brand decoder??[?]

Thanks.

[cacole]

If a decoder complies with the NMRA DCC Standards and Recommended Practices, every CV will be exactly the same between them except the CVs that control sound, because the NMRA standards were adopted before sound decoders came onto the market. So CV 2 on one brand should be exactly the same on every other brand, because it is one of the NMRA DCC standards.

[jrbernier]

cacole,

This is not exactly true. Basic CV's are 'registered' and can be considered 'common'. Many of the lighting effects/sounds/special functions can vary. If you are looking at common stuff like basic headlights/starting voltage/etc; yes they are pretty much standard. Most decoder manufacturers publish complete CV maps for their decoders.

Jim

[BRVRR]

cacole,
Jim is right on. In my experience, decoders come with a manual or information sheet that gives you the basics for programming that particular brand of decoder. If there are no instructions, you can usually download the manual on the INTERNET. Even the $10.00 Lenz LE1000W comes with an instruction sheet.

[Anonymous]

I would say to avoid the cheap Bachmann/Lenz decoders - they don't have BEMF and sound not unlike a cordless drill's control circuitry (a whining noise that appears at all speeds). The pre-programmed speed curve in the three I have is terrible too - there's a huge jump at about speed step 3 or 4 which makes switching work almost impossible (as well as smooth starts and stops). They can be tamed by fitting them to Athearn BB locos (my three will be fitted to these rather than throwing them away) but in future I'll be buying TCS T1 decoders - the same price but silent and with "Dither" (their BEMF equivelent).

[JohnT14808]

Thank you all for your comments on CVs. I appreciate it. I had been looking at the TCS T1 but was not sure if it came with basic programming instructions like you can find in the digitrax DT400 manual.

[Anonymous]

The TCS decoders come with pretty good documentation, and their website has a downloadable "Easy Programming Guide" that's worth getting. I have a couple of TCS decoders, and they're really good values for the money. Plus, their support is excellent -- I have an older T1 that was having problems with their dither and using a speed table, so I dropped them an email, and they offered to replace it for free with one with the latest software version that doesn't have that problem. Now that's customer service! Plus, they have a 1-year 'no fault' warranty, so even it you screw up the decoder when you're installing it, they'll replace it no questions asked.

[Anonymous]

What would be the purpose of purchasing an "off brand" decoder when Digitrax has what you want for under 20 bucks?

QUOTE: Originally posted by JohnT14808

I have another question:

In shopping around for decoders, I am finding lots of sellers. I need just a basic decoder to handle speed, forward/reverse and lights. Nothing fancy. My question:

If I purchase an off brand decoder, does CV2 on one brand equal CV 2 on other brands? I have a Digitrax programming guide, and am planning on using it to program the decoder I purchase. Can I do this using Digitrax CV values for the CVs that I want to set on this off brand decoder??[?]

Thanks.