# Voltage fun

Discussion in 'FAQs' started by gromit, Jun 28, 2002.

1. ### gromitNew Member

I've read quite a bit about model railroading so far, but one thing confuses me. I've read that some powered track can run at 12V, 18V or even 24V powered track. Do you require locomotives that are comptiable with each of these voltages, or will any locomotive run fine so long as the voltage meets it's mininum power requirements?

Is there a limit to the number of trains I can run on the track? In theory, if I have enough track powered with say a 5 amp power supply, how many trains can I have running the same direction on the same track?

I'm a little confused on this point. Anyone?

-Gromit (the source of stupid questions)
2. ### VicActive Member

Hi Gromit, "There ain't no stupid questions....only stupid answers"

99.9% of HO model trains are 12V DC so don't be concerned about that.

Your question about current consumption (draw) is a very reasonable one. The # of locos that can be operated on a given power supply is dependent on the current draw of each loco.

EXAMPLE: You have 4 locos and a 2 amp power supply Each loco draws .25 amps under load. 2.0AMPS/.25 current draw= 8 locos that the power supply can handle at one time. So you could safely run all four of your locos at once.

There's some other factors to this but they are not of a big concern so the above is a good rule of thumb. Just keep it under the max.

Hope this helped!
3. ### 60103Pooh Bah

Gromit:
To complicate Vic's reply a bit, Not all locos take .25 amp. If you get older locos or some of the big open frame motors, they may pull up to 1 amp. (1 amp used to be the rule of thumb for HO.)
The 18 and 24 volts may be for DCC. I think Z takes a lower maximum and G may take a bit more.
I think in theory that motors should accept voltage above the nominal value, but it would cause the trains to run even more too fast than they do now. (Does anyone understand what I just tried to say?)
4. ### VicActive Member

Hi David, I understand what you are saying The .25 Volts was just an example so that it would give a large number in the end result for illustrative purposes.

I think that the 18 and 24 volts that you are reffering to is input voltage to the DDC system and while some systems may put more than 12 volts to the rails the end result from the decoder to the motor etc is a maximun of around 12 volts. High quality can motors can't stand much more than their rated voltage/current becuase of the heat that is generated under a load.

Guess we have confused the H*** out of Gromit.... all he asked was what time it was and we told him how to build a clock!!!!!! But "great minds" always work in unison!!
5. ### 60103Pooh Bah

Gromit/Vic:
I've just retired after working for actuaries for over 30 years. You get used to specifying all the little variations that might crop up, and eliminating misunderstandings by making the end result totally opaque. Like lawyers, but with these guys the bill adds up correctly.
6. ### VicActive Member

Hi David, Know exactly what you mean....I retired after 32 years as an examiner for an insurance company Talk about having to "dot the i's and cross the t's" Just like a lawyer....only a whole lot less pay