If I understand what I read in the instructions...you hook up track power to the PM42 Quad Power Manager(s)...then come out with 4 different buss lines for 4 different isolated areas or districts. Sooooooooo...as opposed to the old one buss line for the whole layout you now have 4. Is this correct ? Can it really be just that simple ? I am in the process of prewiring my layout before I set down the plywood and want at least this part done right. TIA
George, While I have not wired my layout yet, my understanding is that it is that simple. The 'key' is that the length from the power supply to the PM42 + the length of one of the busses + the distance to the end of the track of your farthest feeder should not exceed 30 feet. So you might want to mount it in the center of your layout. There is good information in this forum on the distances of the 'busses' and all sorts of all stuf. DCC is easier than it sounds ... Paul * edited to include the length of the track section etc
Yup. That simple. Like the circuit breakers in your house, the PM42 provides protection to 4 segments of the layout. The protection built into your DCC system protects the overall system from overcurrent. The PM42 protects the locos and rolling stock and limits the impact of any given short to that layout segment alone.
Yes, it is that simple. What is a PITA is getting the wires soldered to the correct connections. It is very easy to have a very small drop of solder touching between pins giving a short. You will be so glad when you finely finish. I have to re do both of mine as I have made enough changes to the layout that rewiring is now a must. I do not look forward to it. But it must be done.:crying:
I also recently re-wired everything on my modular layout which involved ripping out ALL of my old DC wiring, soldering new feeders to every piece of rail (on the bottoms of the rails) and installing 12ga. low-oxygen red/black zip speaker wire for the power busses, with 14 ga. low-oxygen stranded sub-busses, connected to all those 6" long 22 ga. solid core feeders. Took me about three months to do a 9' X 20' modular layout, with 8 modular sections, 4 of which are new and didn't involve any demolition. I divided the layout into three power districts, each mainline is its own and the Park City Yard and branch are another, and called them Red, Yellow and Green lines (innovative eh??). I built a "Portable DCC Power Board" which includes a PM42 between my command station/booster and my three power districts, and it was as simple as described. I had no problems soldering 12ga. wire to the PM42's "socket", even though 12 ga. wires are too big to be inserted into the oval holes of its metal connectors. Digitrax recommends using 16ga. wire between your command station/booster, and then 14 ga. minimum wires for everything else. I guess I'm just a 12ga. kinda guy. I don't see any recommendation or requirement anywhere on the Digitrax site for Paul's stated 30 foot rule. Everything I read says that 50' is the longest recommended power buss length. That means you can place your command station/booster in the middle of two 50 foot lengths of busses (as per Digitrax's instructions) for a total run of 100'. Nowhere was it mentioned that that recommendation was chopped 20 feet if you put a PM42 between the command station/booster and your track feeders. I would be interested in where you (Paul) found that recommendation. My thought is that buss length may be shorter with smaller, lower quality wire. Although Digitrax states that it's the voltage drop of 1-something volt in 50 feet that's the problem, I'd say the bigger problem would probably be signal strength, which is vastly enhanced by using quality wire. So, don't scrimp on your wire...any of it, when planning for DCC. I picked up a 500' roll of top-quality, low-ox, black/red zip wire at eBay for less than 70 bucks...including shipping. I don't know if that deal is still valid, but I'm going to guess that it still is. It is also offered in 14 and 16 ga. for slightly less. Here's a photo of my "power board" which is portable since my layout and I go to various shows in the Intermountain area of Utah, Idaho and Wyoming. One thing I have noticed is that if there's a short on one power district, they ALL go dead for a second. I've still got to mess with the response time before the Evanston Show on the 3rd of August. Cheers! Bob Gilmore
Bob, Ther 30' rule of thumb is from http://www.wiringfordcc.com/track_2.htm and some other stuff I have been reading. Lots of overly technical information but for me, the take away was 30' from the power supply/booster to the farthest end of a 'circuit' with 12awg busses and I would be a happy camper. Paul
The length is dependent on the amount distortion of the waveform and the loss of power. The distances quoted by sources are assumptions based on non-optimal conditions. It is affected more by the material characteristics of the wire. In addition to low oxygen content, there is also the purity of the copper, how many strands in the wire and what the twist rate of the wire is. With good soldering and high quality wire, 300 foot and longer power districts can be done. The theoretical mathematical limit of the power district is close to 1/4 the wavelength of the carrier frequency. In the case of DCC, that is around 37,500 meters assuming no losses. Since that is not possible due to the track and wire characteristics, the limits become empirical based on the quality of the signal and the amount of power in the waveform. The "Quarter" test is pretty valid. If that short does not trip the power, then your length is too far and the signal is too degraded for the system to acknowledge. Unfortunately the best way to know the quality of the signal requires both an oscilloscope and a spectrum analyzer. Not things on very many peoples garage shelves. So the restrictions in length are more or less what give you acceptable operations. But there is another twist, when they say 50 feet or whatever, they are usually talking about powering one track element. if you power multiple tracks from the same bus, the actual electrical length is different than the physical length of the bus. So results will vary again here. Heck results can vary based on what alloy is in the track that you use. If you intermingle track manufactures and the alloys are a little too different, they will cause corrosion and eventually could stop conducting at that joint. As Bob Gilmore said "So, don't scrimp on your wire...any of it, when planning for DCC", is great advice. Go with the highest quality materials, and take care in soldering, and watch out for incompatible alloys, and life will be so much easier. Last but not least, if you can afford a RampMeter by DCC Specialties, it is well worth the investment! It can help diagnose DCC issues quickly and easily.
Ok...this is where it gets confusing for me... Digitrax recommends using 16ga. wire between your command station/booster, and then 14 ga. minimum wires for everything else. Ok...trying to wrap my head around the fact that the larger the wire gauge...the smaller the wire. That being true....buss wire (16ga.) is smaller then feeder wires (14 ga.) ? It all just doesnt even sound right...hmmmm.
George, After reading all of the material on the link I posted earlier and a lot of other reading material, I decided on 12ga stranded from the Command Station to my PSX DCC (PM42 equivalent) and 12ga stranded from there for my 4 busses. I will use 22ga solid as feeders to the track. I have not yet decided what I will use for Wabbits & Tortoises or anything else that I will be adding. Paul
George, Make life easy on your self. Your layout inside the RV will not have enough length to worry about. Just get a quality 16 gauge wire and 22 gauge feeders and be done with it. Never mind the Digitrax recommendation, it is a generalized statement. It may cost a little more, but you will save your sanity in the end. Checkout www.powerwerx.com, good quality wire for what you are looking to do.
I used what I had the most of. That was 12ga. for the main buss to the PM42s and then 14ga for each section of the PM42. Then the same for the track feeders. I just removed some of the strands on the track end to make each piece thinner for soldering to the track sections. Worked just fine for 4 years.
As I previously wrote, I'm using premium 12ga. Low-Oxygen, ultra-pure 61 strand copper speaker wire as my main power buss. Off of that, I use 14ga. sub-busses, which my 22ga. solid core copper track feeders get attached to. That's three gauges of wire, with the 14ga. premium copper wire not longer than four feet, and the 22ga. solid core track feeders not longer than 6 inches. Here's a funny photo of my red feeders (this doesn't show the black feeders) before I stripped insulation off the tops, flattened and bent the wire, then tinned the tips to be soldered to the undersides of each piece of my code 55 and code 40 rails, with a maximum run of 3 feet of Railcraft and Micro Engineering flex and hand-laid code 40. On longer pieces of rail, the feeders are soldered close to their center for a maximum Nickel Silver rail run of approximately 1.5 feet. Soldered rail joiners are now only for mechanical rail alignment. View attachment 46541 In this photo you can see the red/black 12ga. zip wire, the 14ga. sub-busses and all those red and black 22ga. feeders. Also visible is my 12VDC power line, which powers both my Tortoises as well as my Digitrax UP5 Loconet Panels. Definitely neater and exponentially more organized than my previous DC wiring! Since my layout is modular, it's a real plus to be able to put each module on its side on a 6' table to do work on the underside. Although the switch to DCC seems daunting, the wiring is actually much more simple than what I had done in DC to allow parking trains, de-consisting, simply traveling from east-bound to west-bound trackage. Of course, DCC allows me to do things and run trains in ways that are simply impossible with good ol' DC. It was a lot of work, but it was absolutely worth it to convert to DCC...even spending a week on one module sorting out several phantom shorts. Hope these photos assist you in your DCC project! Cheers! Bob Gilmore
Thnxs David... ^5 As much as I value everyones input...I value your electronics input the most...with you being a self procalaimed electronics nut and all...LOL. Thanks again
George I am not self-proclaimed, Arizona State University, UCLA and CAL have all conferred those credentials to me. I have been a working Electrical Engineer for a long time.:happy:
Didnt mean to disrespect your credentials David. I just seem to remember a reply on some thread where you professed your love for it all. Maybe self proclaimed was the wrong terminology. You just know more on this stuff (electronics) then I do/will in my little pinky. OK...I'm impressed enough that I seek out your replies on many threads...sue me...LOL.
Hey, those sheepskin factories can confer all the degrees they want on you, but only YOU can decide if you are a "nut" ... (spoken one degreed EE nut to another, of course...)
I am not a nut, but I have such a deep passion for my work! Does that make me a nut? And I wouldn't go so far as to call them sheepskin factories..... I Just loved keeping it all in the PAC-10! And studied where I was working at the time.
David...I got the 16 gauge wire for the buss wires from http://www.powerwerx.com/ today. Do you solder the 16 gauge wire to those really small terminals on the 44 pin connector for the PM42 quad manager ?? Seems like really big wire for such small pins ...lol. I'll be running the buss wire starting tomorrow. I also bought a spool of 22 gauge for the feeders.
George, I soldered 12 ga wires to my connector without any issues. I went one step further and wired every usable connection to barrier strips. All wires have spade lug connectors soldered to them. This allows me to attach / detach wires with a screw driver. Jumpers provide more connections if needed. I also mounted the connector to an aluminum L bracket and added a 12V DC power supply jack. Everything is mounted to a board which in turn is mounted to the bench work. This approach has worked extremely well for me. Hope this adds to your perspective. Jerry
