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Q: Are the Voltages on the Rails Dangerous to Children?
The maximum voltage regarded as safe for human contact is nominally anything less than 32 volts. The maximum "safe" voltage was 48V, but that has been reduced over the last few years. For this question, AC and DC are considered to be the same risk. Anything over 48 volts is considered "high voltage" and as such, is not allowed in this application.
However, there is more danger from heat generated by shorting the tracks with metal objects, such as bracelets or necklaces. Fortunately, your booster should detect the short and cut the current. Before that happens, the metal may get warm or even hot. The child may be scared and even slightly burned, but not seriously harmed. If operating properly, the booster should disconnect the track power the instant a short occurs.
This is yet another reason to test your wiring to make sure your booster's short circuit protection works on all sections of track. The simplest method is a called the quarter test, where a coin is used to short the rails together. If the reaction is not instantaneous, the wiring to that section of track needs work.
Q: Can I Quickly Change from DC to DCC and Back Again?
Yes, simply wire for multi-cab control as you normally would for DC. However, do not use common rail wiring. Also, use #14 or better bus wire (see Track wiring for details). When you want to change from DC operations to DCC, simply hook up the booster in place of one of the cabs and switch all blocks to that cab. When you're ready to go back to DC, simply flip to the block toggles back to the DC cabs.
- Running Analog and DCC power on the same layout is dangerous, as a mistake will destroy something. Run your trains using only one method at a time.
Once you experience Digital Command Control, you will soon forget about analog operations.
Q: Can I use Other Brands of Boosters on my Digitrax System?
Yes, but they must be connected in very specific ways. Only the Uhlenbrock Intellibox systems can be directly connected over the Loconet. Any other system will require you to make special cables to connect the other boosters.
Q: Can One Command Station Control Multiple Layouts?
Short answer: Yes. It's possible to control two (or more) separate layouts using a single command station. For instance, if you wanted to operate an N scale layout inside and a G scale outside. Most systems combine the command station and booster into a single unit. Either case, you connect one layout as normal, that is, connect the command station/booster to one layout. Then, you simply purchase a second power supply and booster for the other layout. The second layout will receive it's commands through the throttle network (LocoNet, XpressNet, etc). This allows you to have same, or different voltages for different layout sizes.
Assume we have an N scale layout in the garage. Since power requirements are low, we purchase a DCC system that outputs about 2 to 3 amps, and the voltage is set for N scale. We setup this layout as described in other parts of this website. A year later, we want to setup a G scale, or garden railroad in the backyard. To do this, all we do is purchase another power supply and booster for the second layout. Because the power is independent of the layout, we don't need to worry about the higher voltage from the garden railway making its way to the N Scale layout. To get the commands from the command station to the garden railroad booster, we simply connect the throttle network (such as ExpressNet, or LocoNet) to the booster. We now have two railroads being controlled from any throttle, at any location, with a cost savings by not having to purchase two command stations.
Q: Can an unmodified locomotive operate together with a DCC locomotive at the same time?
The standard allows for this, although some care needs to be exercised in its use. We refer to this type of operation as analog compatibility mode. The signal is symmetric around the 0 volt level which provides a 0 volt DC component. By expanding the length of the zero bits on the positive side of the signal a positive DC component can be added. Likewise, by lengthening the bits on the negative side of the signal a negative DC component can be added. Only the 0 bits can be lengthened in this manner.
The result is a non-zero average DC voltage which will run an unmodified locomotive. However, since the complete signal gets to the motor, the stretched zero side causes the motor to turn, and the following instant the unstretched side (the opposite polarity) tries to reverse the motor. The longer (stretched) side wins, but motors do run more noisily and generate more heat. Some high precision can motors (the ironless core type) may be permanently damaged. (See the following question.)
Q: Can the UT-4 be upgraded to UT-4R?
Q: Can the digital decoder send information back to the command station?
In service mode the digital decoder can acknowledge a packet with a brief pulse of current. This can be used to find out the digital decoder’s address, for example - send a packet asking the digital decoder if it is address 1 and wait for a response. If no response, try address 2, etc. There is currently no defined way to send information back to the command station in normal running mode, although some work is being done in this area to determine what is feasible. See the extended packet format RP for a description of feedback in service mode.
However, some systems like Digitrax can have limited feedback locomotives, called transponding.
Q: Can you control things other than locomotive speed and direction?
Yes. The baseline packet in the standard only provides for basic locomotive control since that is all that is essential for interoperation. The extended packet format RP defines packets that can be used to control 32,000 different accessories such as lights, sound, turnouts, etc.
Q: Can you run a digital decoder equipped locomotive with a conventional 12-volt DC power pack?
This is an optional feature of digital decoders provided for by the standard. If a digital decoder supports analog operation, and it does not see a digital signal on the track, it reverts to analog operation and can be controlled as if no digital decoder were present. Decoders can be confused by some forms of very narrow pulsed power and extreme care must be taken to ensure that the packs maximum output is less than the decoder’s 24 volt maximum.
Q: Does every layout block need transpoding installed?
Transponding does not need to be used over the entire railroad. Software such as RR&Co's Train Controller need only identify an engine in a start block of a schedule. This can be done at the computer's keyboard so transponding is not necessary. It simply can automate the process. All of the detection is done by the BDL boards and the identity of the train is tracked in the software.