Transformer Power

[SteveWard3928]

I have a 2 Amp transformer arriving today (My layout is under 300 feet)  to replace the generic that came with a starter set.  I want to learn how to figure the Amps of this generic transformer.     This is what I am reading on the transformer:
Input: 120VAC
60 HZ
28 W
OUTPUT:  17 VDC
MAX OUTPUT:  11 VA

I am guessing it is somewhere between .5-1.0 Amps.  Does anyone know the formula used to calculate the Amps?   Thanks for any insight.    Steve


Thanks for the info. Right now I am just running my 4-6-0, tender, boxcar and caboose.  No extra lighting is involved...so far.  However I have to wonder if this generic "Hobby Transformer" Model #6609 is really putting out 1.65 Amps.  That seems a little to powerful to be the one that comes with a starter set.

[Chuck N]

I think the "11VA" is the number that you start with.  That is the highest number you will get if you multiply the volts coming out by the amps being used.  For your power supply Volts X Amps = 11.  So if you are runnint at 11 volts the unit can handle a 1 amp load.  If the voltage output is 1 volt it will handle 11 amps.  The higher the VA the better the power supply.

At the full 17 volts out put you will have 11/17ths of an amp.  Barely enough for a one motor engine let alone a smoke generator and a car with lights.

Most of us use 10amp or higher power supplies.  Your new 2 amper won't run much at all.  It will overheat and cut out frequently.  I have 2 10 amp power supplies and one 15 amp.

If you have 300 feet of track you are most likely to be running long trains with larger engines having more than one motor.  When planning your power needs figure on one amp per motor.  For most engine motors that is a little on the high side, but it is better to have more power than not enough.

Lighted cars will also add to the current draw.
Chuck

[Loco Bill Canelos]

Hi Steve,

This is the formula  Amps = Watts / Volts. (Amps = Watts divided by Volts)

That would make yours 28/17 = 1.65 AMPS

[glennk28]

I have found that a popwer supply givingb at least 5 amps is essential for most large scale locos, particularly those with more than one motor like the Shays, and other logging locos. If you are into electronics, a good supply can be built using a Lionel #0133 transformer with abridge recitfier and revertsing toggle on the ouitput.  The variable transformer that is part of the 1033 serves as speed conrtol, and the 85-watt output is more than enough--giving over 5 amps. 

These transformers can often be found at flea markets for $5-10.   

[Mcapp]

GlennK28

I have one of these 1033 transformers, how do I convert it to DC power so as not to damage the motors?

mcapp

[glennk28]

connect a bridge rectifier--the 2 "squiggles" on the bridge go to the transformer output asyou would connect it for Lionel use.  , the + and - are the DC output.  Then a DPDT toggle cn be wired as a reversing switch. Linn Westcott"s Book "How to Wire Your Model Railroad" has diagrams.  the Lionel throttle will control the train thru the rfectifier and toggle.  gj