Before I travel the 110 miles to Savannah to pick up my new Digitrax Empire... system, I hope someone can answer a couple of questions regarding something called, "boosters". I want to be as informed as possible before I plunk down any more dineros$$$. And, this forum has been good for me, so far, during the construction of my HO guage layout.
What are "boosters", exactly? Why, and how often would one need to install them? Are they simple to wire - in parallel; in series/or not? Thanks...
"G. Flash"
The command station sends a digital pulsed signal to the booster which adds a constant voltage DC current to the track. The booster is just what it sounds like. It boosts the current and signal together to the track which in turn gets sent to the decoder which puts motion or functions from the digital signal. The Command station is the brains and the booster is the muscle. Depending on the load that's placed on the system will determine how many boosters you will need. Our clubs modular layout uses a booster for each main track and 2 boosters for the third track and all the sidings and yards. They are all 5 amp boosters. My friends Digitrax system uses 2 five amp boosters on his 40 X 50 foot layout. We generally run 19 trains simultaneously during an op session. Sometimes more sometimes less. Any typical home layout will only need 1 five amp booster split into sections by different power districts. You will need a different power supply for each booster. Do not use a 10 amp power supply for 2 boosters. Match your boosters to the power supply.(5 amp to 5 amp). A ramp meter hooked into the boosters output will let you see how taxed the booster is. Tonys trains has them or maybe your not so local shop will have them.
http://www.tonystrains.com/products/tteexclusive_measure.htm
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
You might also consider joining this Digitrax DCC group with a lot of Digitrax specific information as well as connecting to other system decoders. They have a list of over eight thousand members, though a lot come and go.
http://groups.yahoo.com/group/Digitrax/
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Every DCC system needs one (and only one) command station and one or more boosters. The DB150 that is the heart of the Empire builder system contains a command station and a 5 amp booster. They are both inside the same DB150 case. The command station puts out a low current version of the DCC signal. The command station also communicates with other devices that are connected to the system e.g.throttles.
The booster 'boosts" the low current signal from the command station so that it can run trains. The command station in the DB150 can be disabled via a jumper wire so that only the booster works. This allows additional 5 amp boosters to be connected to the one and only one command station. They will also boost the low current signal from the command station. Instructions for doing so are in the manual but really not a concern unless you would need more than one 5amp booster to run your layout.
Martin Myers
locoi1sa The command station sends a digital pulsed signal to the booster which adds a constant voltage DC current to the track.
The command station sends a digital pulsed signal to the booster which adds a constant voltage DC current to the track.
This is not correct. For practical purposes it doesn't really matter, but the booster takes a DCC signal, which may be at track voltage, or not, and send it to the rails at track voltage (digital pulsed signal, not pulses with a DC component), with the current capacity of the booster.
My biggest point is that there is NOT a constant DC voltage in the DCC signal. Rather it is a bipolar signal that is recitfied by the decoder to generate the DC that is used to run the train. That's why there's no direction to the signal, unlike regular DC.
Jeff But it's a dry heat!
Since you are heading to the hobby shop to purchase the system,be aware that the DT400 throttle has recently been superseded by the DT402 throttle. Unless you are getting a really good deal on a set that they have had on the shelf for a while, make sure you are getting the new throttle.
Simon Modelling CB&Q and Wabash See my slowly evolving layout on my picturetrail site http://www.picturetrail.com/simontrains and our videos at http://www.youtube.com/user/MrCrispybake?feature=mhum
locoi1sa The command station sends a digital pulsed signal to the booster which adds a constant voltage DC current to the track. The booster is just what it sounds like. It boosts the current and signal together to the track which in turn gets sent to the decoder which puts motion or functions from the digital signal. The Command station is the brains and the booster is the muscle. Depending on the load that's placed on the system will determine how many boosters you will need. Our clubs modular layout uses a booster for each main track and 2 boosters for the third track and all the sidings and yards. They are all 5 amp boosters. My friends Digitrax system uses 2 five amp boosters on his 40 X 50 foot layout. We generally run 19 trains simultaneously during an op session. Sometimes more sometimes less. Any typical home layout will only need 1 five amp booster split into sections by different power districts. You will need a different power supply for each booster. Do not use a 10 amp power supply for 2 boosters. Match your boosters to the power supply.(5 amp to 5 amp). A ramp meter hooked into the boosters output will let you see how taxed the booster is. Tonys trains has them or maybe your not so local shop will have them. http://www.tonystrains.com/products/tteexclusive_measure.htm Pete
There is a great deal of inaccurate information in this post.
DCC is not DC, it is square wave AC. The command station controls the spacing of the waves to provide a digital communications signal for the decoders.
The device commonly called a booster is actually a slave command station. It provides the same voltage as the command station but the signal embedded on it is generated by the single command station which it receives via some kind of communications buss. With Digitrax it is called Loconet. It does not boost the voltage or signal from the command station; it powers a separate electrically isolated section of the layout. The limit is determined by the number of trains on it's particular section of the layout.
The size of the layout is irrelevant. The command station has a current limit. The number of trains and other electric loads such as lighted cars determines it's capacity. Most layouts do not need any boosters, just a single command station. Some club layouts that are running many trains do.
Using a 10 amp power supply on a 5 amp booster will not hurt anything. It will also not increase the 5 amp limit of the booster.
Dave
Lackawanna Route of the Phoebe Snow
Vail and Southwestern RRMy biggest point is that there is NOT a constant DC voltage in the DCC signal. Rather it is a bipolar signal that is recitfied by the decoder to generate the DC that is used to run the train. That's why there's no direction to the signal, unlike regular DC.
I'm confused, as usual. I thought the booster supplyed a constant DC voltage to the track and the command station signaled the dedcoder what to do with the power. That is break it up into pulses and send it to the motor, or supply power to the lights or sound.
Lee
This is how it was explained to me and what I got from reading everything I could get my hands on about DCC. I have a medium size layout under construction with one command station with a two track mainline and one branch line each having it's own booster, not so much for the sake of running more trains or having more power but each section is isolated from each other therefore each line has it's own circuit breaker protection built in to the booster. It may be a little overkill but I figure the added insurance is worth the extra cost.
Using separate boosters to isolate sections of the layout sure will work, but the cost is astronomical. There are much cheaper ways to do it .
http://digitrax.com/prd_powerman_pm42.php
yankee flyerVail and Southwestern RRMy biggest point is that there is NOT a constant DC voltage in the DCC signal. Rather it is a bipolar signal that is recitfied by the decoder to generate the DC that is used to run the train. That's why there's no direction to the signal, unlike regular DC. I'm confused, as usual. I thought the booster supplyed a constant DC voltage to the track and the command station signaled the dedcoder what to do with the power. That is break it up into pulses and send it to the motor, or supply power to the lights or sound. Lee
The DCC signal is the power, or the other way around, if you want to look at it that way. It's made up of square/rectangular pulses that are high and low for the same time, so the average voltage, relative to the midpoint, is zero. That's why you can set a DC loco on the tracks and it doesn't move. However, you have probably noticed it hums, that's because the motor is getting driven alternately forward and backward for short, equal periods. The length of the pulses is varied to create a serial digital signal that the decoder uses to determine what actions to take.
The good thing is that to use it, you really don't need to know how it works.
As far as the initial poster's question goes, I think the booster in the command station he is getting is most likely more than sufficient for his railroad. As has been said, there are ways to break the layout into sections using a single booster that are more cost effective than adding more boosters.
Vail and Southwestern RRThe good thing is that to use it, you really don't need to know how it works.
I think that is the problem most of use have. If we can understand what voltages and an scine waves are seen at the track everything else would make more sense. Would not it have been easer to supply voltage to the track and send information packets riding that voltage? Just an idle thought.
Inquiring minds would like to know.
yankee flyer Vail and Southwestern RRThe good thing is that to use it, you really don't need to know how it works. I think that is the problem most of use have. If we can understand what voltages and an scine waves are seen at the track everything else would make more sense. Would not it have been easer to supply voltage to the track and send information packets riding that voltage? Just an idle thought. Inquiring minds would like to know. Lee
OK, you asked for it!
There would be a couple of disadvantages to putting voltage on the track, and adding the signal to it. First, if you put DC on the track, the left and right rail would have meaning. By using the bipolar signal, and recifying it, the polarity of the power is "known" to the decoder, so forward and reverse are defined by the decoder, and not by the rails. Secondly, using the bipolar signal means the amplitude of the signal is huge, it's since it is as large as the power. That makes it quite immune to interference. If it was a small signal added to a DC voltage it would be much more susceptible to noise, especially with a little noise making motor in every locomotive. The other advantage of the DCC method is that it allows the use of a DCC locomotive, though this is becoming a less used feature as time goes on.
If one had an oscilloscope, and looked at the DCC signal at the rails, it would actually be simple to understand, and pretty easy to decode. Have a look at this: DCC signal from the NMRA horses mouth. It might make things a lot clearer!
One thing nice about Digitrax (and many of the other systems too) is you can start small and easily add boosters etc. later. I've been using my Zephyr for maybe 5 years now and so far it has all the power I need. At first I used just the Zephyr and it's controller, over time I added a UT-4 walkaround unit, and just added a UR-90 infrared receiver to go wireless (most Digitrax throttles are set-up for infra-red, just need to add a 9V battery) and will be adding more in time. If as the layout expands I need more power, I'll add a booster. For me, I'd rather do it a step at a time as needed.
This is what some old, pre-DCC systems did, and no, it is NOT better. It is in fact, far far worse. he reason is that the control signal would have very little amplitude, adn easily be lost within motor noise, dirty track and wheels, and dirty power pickups. The huge advantage of DCC is that the signal and the power source are one in the same. The DCC signal is a square wave (nothing to understand - it's well, square (ok actually rectangular)). It is equally centered about a zero reference point, meaning half is positive relative to this reference and half is negative. Peak to peak it's about 14.5 volts for typical HO system, more for large scale and less for N and Z. The amount of time the signal is at either peak determines if the data bit is a 1 or a 0. Below a certain threshold, it's a 1, anythign over a certain threshold is a 0. Combinations of these 1's and 0's send the commands to the decoder to control speed, direction, and function outputs. The frequency is variable, because the 0 bits are longer duration that then 1 bits, but the overall frequency is high enough that commands can be set for hundreds of locos without making it too slow to respond.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Just to clarify the earlier response. I just wanted to give a simple explanation on what a booster does. I did not want to confuse the OP with a whole dialog with technical terms and language that would not be understood. It was not my intention to confuse. Square wave DC is not the same as AC. AC has a consistent frequency (spaces between high and low.). Square wave DC signals are not spaced consistently. That is what gives the decoder the information it needs.
Hope this helps.
locoi1sa Just to clarify the earlier response. I just wanted to give a simple explanation on what a booster does. I did not want to confuse the OP with a whole dialog with technical terms and language that would not be understood. It was not my intention to confuse. Square wave DC is not the same as AC. AC has a consistent frequency (spaces between high and low.). Square wave DC signals are not spaced consistently. That is what gives the decoder the information it needs. Hope this helps. Pete
SOoooooooo The command station triggers the booster to mimic the command stations out put. The command stations out put only reaches the booster, which then replicates the signal and sends it on to the track with a higher current draw possible? If that's the case then a lot has been cleared up for me.
Thanks
DCC waveforms from Alan Gartner web site.
http://www.wiringfordcc.com/dcc_waveforms.htm
This is sure to confuse some folks.
locoi1saSquare wave DC is not the same as AC. AC has a consistent frequency (spaces between high and low.). Square wave DC signals are not spaced consistently.
Phoebe VetUsing separate boosters to isolate sections of the layout sure will work, but the cost is astronomical. There are much cheaper ways to do it . http://digitrax.com/prd_powerman_pm42.php
Oh absolutely but I'm thinking of future expansion down the road, unfortunetly I am having to build this pike in sections as negotiations keep breaking down with the other owner of or should I say owner of all this STUFF in the rest of the basement. So far it's cost me a brand new washer & dryer from Lowes but her stuff is still here whats wrong with this picture?
Phoebe VetThe device commonly called a booster is actually a slave command station. It provides the same voltage as the command station but the signal embedded on it is generated by the single command station which it receives via some kind of communications buss.
I agree with you. In my attempt to put it into words that the OP would understand, I phrased it poorly.
His question about whether to wire it in parallel or series indicated to me that he didn't understand how boosters are used and I was trying to clear that up.
I never thought about the signal generator as a separate device in a common case. To me a command station has that circuitry and a booster doesn't. On that I stand corrected.
Allegheny
Ha. Remember this. Whats hers is hers and whats yours is hers. To you its train stuff to her its the junk you play with. My basement is unsuitable for a layout. I waited years for one kid to move out. They moved out and I thought Yah I have the whole upstairs for my own. Well surprise surprise. They move back in and then back out and then in again. Its not so much the in and out but when they move out they leave more stuff behind. Now most of the upstairs is storage for their stuff. One of these days there is going to be a big dump run I told them. Luckily I took the large room for my train stuff. Quick build benchwork before they move back in again!
LOL
CSX Robertlocoi1saSquare wave DC is not the same as AC. AC has a consistent frequency (spaces between high and low.). Square wave DC signals are not spaced consistently. You're right that square wave DC is not the same as AC, but the DCC signal is not square wave DC. There is no DC component to the DCC signal. It IS square wave AC. Having a consistent frequency is not a requirement for being AC.
DCC very much has a DC component but not in the normal sense that most folks are accustomed to. DCC uses a differential baseline encoding technique across the A/B outputs. What this means is that the bipolar or unipolar pulses on each rail are 180 degrees out of phase with each other and maintain a DC differential voltage. The DCC signal is essentially encoded over a DC component that can easily be extracted. Telephone companies have used this technique for years to power line repeaters. It is this DC differential component that is used to provide the power to the motor, lights and other load devices. Otherwise large filterting capacitors would be needed on each locomotive to maintain the current flow to the load when the waveform signal would normally drop. The signal is not AC. We've been down this discussion road here many times before.
Here's the NMRA Standard . Section 2.2.1 is the booster output section.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
jbinkley60...What this means is that the bipolar or unipolar pulses on each rail are 180 degrees out of phase with each other and maintain a DC differential voltage...
Save yourself some time and travel and money in the long run and get the super chief.
http://www.digitrax.com/prd_scfx_set.php
Railcon44
CSX Robertjbinkley60...What this means is that the bipolar or unipolar pulses on each rail are 180 degrees out of phase with each other and maintain a DC differential voltage... The two rails do maintain a differential voltage but with a constantly ALTERNATING polarity, hence it IS AC. It is not what most people think of when they say AC, it is not a sine wave and it is not a consistent frequency, but neither of these attributes are a requirement for a voltage source to be AC.
Your statement about alternating polarity is partially correct and limited to whether the manufacturer chooses to use bipolar vs. unipolar encoding. You can't tell the difference unless you know the refence point and place a scope on the rails. If they choose to use unipolar encoding then the signal never crosses the zero reference point and thus never changes polairty with respect to the reference point.
The NMRA spec says:
bipolar signal must appear differentially on a two-wire cable with a signal amplitude of no less +-8V and no greater than +-22V. The Command Station output must be capable of supplying +- 8 volts into a 1K-ohm resistive load, so that multiple Power Stations may be connected to this output.
A unipolar signal must appear on a two-wire cable, one signal, one ground, with a signal amplitude of no less +8V and no greater than +22V. The Command Station output must be capable of supplying +8 volts into a 1K-ohm resistive load, so that multiple Power Stations may be connected to this output.
You can see that the unipolar method had no negative component and does not cross the zero reference point.
Personally I am not sure why the NMRA chose to support both encoding methods. Either are valid and boosters are supposed to support both to maintain compatability.
jbinkley60The NMRA spec says: bipolar signal must appear differentially on a two-wire cable with a signal amplitude of no less +-8V and no greater than +-22V. The Command Station output must be capable of supplying +- 8 volts into a 1K-ohm resistive load, so that multiple Power Stations may be connected to this output. A unipolar signal must appear on a two-wire cable, one signal, one ground, with a signal amplitude of no less +8V and no greater than +22V. The Command Station output must be capable of supplying +8 volts into a 1K-ohm resistive load, so that multiple Power Stations may be connected to this output.
jbinkley60Your statement about alternating polarity is partially correct and limited to whether the manufacturer chooses to use bipolar vs. unipolar encoding. You can't tell the difference unless you know the refence point and place a scope on the rails. If they choose to use unipolar encoding then the signal never crosses the zero reference point and thus never changes polairty with respect to the reference point.
Once you get to the rails, you don't know or care whether it's bipolar or unipolar, since you don't know, or care what the reference point is. At the rails, with respece to each other, it looks the same. By writing the spec the way they did, the NMRA specified a signal with no "ground" or reference at the rails, allowing for a differential signal with no reference other than itself.
Thinking about it that way, I guess one could say that it has characteristics or DC, AC, neither, or both. It's a differential signal that can supply enough current to be used for power.
Another Engineer Jeff.....
The only reference available to the decoder is the two rails. If it was not AC at the rails then zero stretching to run a DC engine would only work in one direction. If you put a scope on the two rails you will see AC because first it flows from rail A to rail B then it flows from rail B to rail A. Except when you are using zero stretching, it is symmetrical.