Preseli PeteHow many transformers will I need?
the question suggests you may not be aware of how locomotives can be controlled using today's tech.
early locomotives were controlled using a transformer to reduce the AC line voltage (~120 VAC), a (selenium) bridge rectifier to convert to DC and rheostat, an adjustable resistor to further reduce the voltage to the track. The resulting track voltage determines the speed of the locomotive
more modern DC controllers used semiconductor diodes and transistors to provide regulated voltage to the track.
And while there are various other approaches, a more common one is to use pulse width modulation (PWM) which rapidly turns on and off the full supply voltage resulting in an average voltage for controlling a DC motor.
but the other advantage of PWM is that the full voltage supplied even for a short time overcomes the "stiction" of a motor at very slow speeds to keep it turning
PWM is also used in Digital Command Control (DCC) systems where a small electronic decoder is installed in the locomotive and is connected directly to the motor. The decoder applies the desired PWM voltage to the motor based on commands sent across the tracks.
a single DCC system (NCE, DiGitrax) can control many locomotives at the same time, while DC controllers that simply control the voltage to the track require isolating track blocks and using switches to connect individual DC controllers to each block
greg - Philadelphia & Reading / Reading
Hi and welcome to the forums!
We're going to need a bit more information to understand your question and how best to reply. A small layout generally needs only one system to power all the trains, assuming the power is sufficient for all the trains. We do try to power the trains separately from lighting, streetcars and such.
A "transformer" is kind of an outdated term from when I was a kid and ran big old Lionels. Technically, a transformer is a device used to "step down" the high voltage used in your house for lights and power tools to something more reasonable for model trains. Pretty much every device I use to power my layout has a transformer in it, so I usually just call them all power supplies. One supply runs the Digital Command Control (DCC) system that runs all my trains. One, an old train transformer called a power pack back then, runs my turntable. Others run building illumination including pizza shop signs. So, my power needs are often specific to what's on the layout.
Oh, in the past this forum, like most, has been bothered by trolls, bad actors who generally insert even more advertising than usual. To avoid this, all new users go through a short period of "moderation" to make sure they're really here to talk about trains, which will delay your next few posts. It's nothing personal.
It takes an iron man to play with a toy iron horse.
Hi Pete and welcome to the forums!
I'm not familiar with that plan as I don't have that book, but generally speaking for DC it comes down to how many trains you want to run at the same time. You'll want one transformer per train.
Hopefully someone with some knowledge of your track plan will chime in.
Cheers!
Mike
I am about to build plan 1c from the PECO setrack n gauge planbook. How many transformers will I need?