Found this on the Soundtraxx Group on Yahoo. Applies to more than just Soundtraxx, too, if you like the idea of the Lenz keep-alive option for the Gold decoders.
http://www.members.optusnet.com.au/mainnorth/alive.htm
–Randy
Thanks Randy. Hard to read the schematic, but it sounds rational. I might ask for assistance on this one.
A point not mentioned in the article (but implied and assumed) is that the “keep-alive” capacitance must be isolated from the track. The capacitor must be installed on the decoder side of the decoder rectifier. It CANNOT be placed across the decoder input. If the command station “sees” the extra capacitance it will result in “smearing” of the DCC packets. Enough capacitance will cause decoder inability to decipher the DCC signal.
Very informative and useful article. Thanks Randy.
yours in signaling
Fred W
Yeah I’d have to look at the actual decoder. I can’t see that both sides of that diode mentioned would be the proper pickup points, unless that happens to be a Zener diode to limit the output voltage of the bridge rectifier - there’s be no reason I can think of to place a regular diode across the DC terminals of a bridge rectifier.
The key is the diode and resistor used with the capacitor - this is what is missing on QSI decoders and causes the current inrush problem.
–Randy
Maybe I’ll bring it in July…
Chip,
I use several Soundtraxx LC decoders in F7 sets. If you are using the decoder in diesels, you could probably use the same ‘fix’ that I use. Since I usually run my F7s in pairs, I tied them together electrically with a 2-conductor Miniatronics plug/wire. It eliminated the stutter. If you are installing the decoder in a small steamer, maybe you could modify the tender for electrical pick-up. The steamers I installed the LC decoders in are all 4-6-2s or larger. No problems there.
Just thought I would throw in my 2-cents.
Hope it helps.