Power Packs

[Anonymous]

I would like to know what pulse,and momentum
mean,and do they damage motors in any way?
Thanks Larryc

[BR60103]

Hi Larry
Pulse power is a bumpy form of electricity. If you take AC, which changes direction 120 times a second, and run it through a bridge rectifier, you get DC that you can run trains on. The current goes always the same direction, but it now goes from 0 to 12 (or whatever) volts 120 times a second.
If you modify the rectifier so that it only passes one half of the current, you get a pulse of electricity for 1/120 second followed by 0 volts for 1/120 second. This batters your motor around to get it started without the "jackrabbit" start we usually get.
Pulse power used for too long a period at higher speeds is said to heat up motors and destroy the magnetism.

Momentum refers to making trains behave as if they have the mass/weight of the prototype. It has various parts and methods; the end result being that when youstart your train it takes time to get up to full speed and when you shut off power it takes time to stop. The main ways to do this are flywheels and electronic controllers. Flywheels are heavy metal cylinders attached to the drive train or motor that keep spinning after power goes off. (They are also good for overcoming dirty track.) The electronic controllers have circuitry in them so that power comes up slowly and goes off slowly. There may be added bells and whistles (!) like brakes and adjustments.
Momentum ususally only damages equipment when you can't stop at the end of track.

David