Voltages for N vs HO

Power pack output is usually rated in "VA" or "volt amps", roughly equivalent to watts (wattage isn't exactly volts*amps for AC). NB that this is the _total_ power output on both DC and AC circuits. If you don't use the AC side, you can draw more amps on the DC side.

There is no difference in voltage between HO and N: both are supposed to be 12V max, and locos are supposed to be designed to reach their prototypically maximum speed at 12V, but few locos do. In practice, many (most?) HO and N scale locos reach their maximum prototypical speeds around 9V.

But there is a difference in power between N and HO. In the Olden Days (before high-precision gear trains and high-efficiency motors), the difference could be substantial. A typical DC motor drew 1/2 amp or more in an HO engine, and about 1/4 amp in an N engine. So p/p for N gauge could be made at lower power ratings.

Nowadays, the difference is less. I've seen recent O scale locos draw less than an amp, an unheard of thing 40 years ago. The minimum power output for any scale in my experience should be 7VA (about 1/2amp at

12VDC), although this will be just barely enough for a small O scale or G scale loco. Note that if you use an underpowered power pack, it may run hot, and the circuit breaker may trip.

HTH

Thanks for the info. Thi is great. I am stting up HO and needed a pwer pack. Found one at a Flee MArket (770N ) for $3.00. It looks new. M