Hi folks, it’s my first post on this forum and i hope you’ll be able to help me…
I’m planning to have DC braking section. It’s an easy way to have trains slowing down and stopping automatically before junction or in front on and red signal, etc…
The question is :
[:-alien]
When a loco runs from the dcc area into a DC braking section, there is a short between the two different currents and this may damage the decoder… Lenz provide the LT100 which resolve the problem but is quite expensive (I will have 16 braking section). Does someone know another cheaper way the prevent shorts between the DCC and DC current???
I posted a very similar topic a few weeks ago, and the best we could come up with is some sort of computer controlled braking section, because DCC uses about 16volts AC current, and you could burn up the decoder of a DCC controlled loco running it on DC unless it was a dual mode type decoder that was made to handle it. Good luck trying to solve this problem, because I’d love to do something similar if it works!
At a DCC session at the NMRA convention two years ago, it was strongly urged that you have no way where your DCC power could meet up with your DC power. At that time, the question was having blocks with DC and DCC on the same layout. The explanation was that the DCC would be very hard on the DC power packs.
I don’t know how Lenz does it, but with the Digitrax DCS100, when you configure it to provide a braking section with the programming track output, it’s NOT DC, it sends a global stop DCC command to that section of track which causes the decoders entering that section to stop the motor. Still a regular DCC signal on the rails.
With Lenz I guess you could use the new Gold Series decoders with the asymmetrical DCC signal to do this. Any stopping block just requires a simple and cheap diode circuit to generate the required signal. There is an explanation on Tony’s web site.
I’m just re-reading thru the quantum manual, they do a dc braking section with diodes and only in one direction if desired.
Dcc power conversion, CV29 bit 2 =1 a Dcc controlled loco will automatically engage dc power conversion when it enters a section of track that is dc powered.
Is this for all DCC decoders or just quantum?
The diagram showen uses diodes in one track to convert the dcc signal into dc there by not causing a short between to different power sources.
If you use two diodes one in each direction and seperately switched
the loco will either carry on at the same speed or stop at the decoders momentum setting.
I think I’ve got this right, it’s an idea I’m going to try, use a DPDT sw and control a signal light as well. Red light, section of track has dc on it, loco slows to a stop until sw is flicked and green light shows.
The fact is that when using a DCC braking section involving a DCS100 or so, you’ll need to have a DPDT or some kind of train detector to activate the “zero” mode when the loco is completely in the section, if a loco bridge the layout and the dcc braking section this will turn everything off!
By using a DC braking section with a LT100 (Lenz), the LT100 will cut the DC current when a short appares; protecting DC power pack and decoder from dual curents; and let the DC running safetly when there’s no short once the loco is entirely on the DC section (Its a kind of reversing loop detector working on 2 different currents). Then the loco will start slowing down…
So The LT100 is THE solution but it costs 35$ each and you need one per braking sections…
This why I was asking for another solution if someone knows one…
Ray : thanks for the jooooooooooooooooke… keep trying… you’re on the right rails…
I don’t know how else you could do it that would remain compatible with ALL decoders.
If you switched every decoder for the new Lenz Gold Series with Asymmetrical DCC, you can do even more with just a few diodes. But that doesn’t help for QSI or Soundtraxx or other brands of motor decoders. Or even previous Lenz decoders, for that matter.
In light of the cost of switching EVERY decoder, the $35 per section for the Lenz unit is a bargain.
I think some are reading too far into this. Having both DC and DCC sections on the same layout is asking for trouble. An engine will cross the gap and may stall on the gap, thus shorting both the DC cab and the DCC system. Spending lots of money to have a ‘braking section’ that may or may not prevent an issue seems like a bad investment.
I too was very interested in this back in the mid-90’s when I got into DCC. I remember a LHS that had DC, DCC, and a DCC program track all on the same shelf layout… They blew multiple decoders crossing the gaps. Most of the time I could fix the decoder for them by doing a RESET on it. Most of the reasoning for wanting to do this is ‘I have lots of DC engines and cannot afford all those decoders’. I too had lots of DC engines, but discovered that some of them did not lend themselves to conversion. When DCC/Sound decoders came out, I found that I was running my BLI USRA 2-8-2 more than the others(I wonder why).
I have about 36 DCC equipped engines right now, and the rest are ‘roundhouse queens’ and sit in the display cabinet - They have decent paint jobs, but the power/drive are not worth putting a decoder in. Last week we had a guy show up at the club with an old Mantua Pacific - He put a MRC steam sound decoder in it. It did not run well as it has only 3 drivers on the right hand side to pick up power, and 6 brass wheels on the left side of the tender to return the power to the rail.
Section B of the RP really is talking about what a decoder does when it senses changes in signal. From experience, I have seen dual mode decoder engines take off like a rocket when they lose the DCC signal(on a DCC layout) due to ‘noise’ on the rails(or even dirty wheels). At our club we have the DC enable feature turned off on our DCS200 command station. We suggest that club members also turn off DC enable on their dec