Using a automotive charger as a transformer for prewar engine.....???

With all the available dedicated hobby power supplies, why would anyone use such an off the wall method?

A car battery charger is 12v dc, so I don't know why someone would use it (though being a universal motor, it can run on DC). Sounds to me like someone looking to do a clever hack, given the price of hobby transformers these days I don't know why anyone would do it.

Interesting that he decided to put the speed control on the A/C input (basically a variac), rather than a rheostat on the 12 v dc output. I can't see how using the A/C input voltage control would work any better at low speed control, the voltage is stepped down and rectified and the a/c input voltage controlled variac isn't likely to be all that fine in terms of voltage 'steps', wouldn't be different than a rheostat would be *shrug*.

Yeah...what they said.

I hope I don't incur the wrath of the "power strip police" police by saying it, but using any electrical device for an application that it wasn't designed for is not a good idea. Not illegal, not a code violation (well, maybe it is) but definitely not smart.

Do you really want 50 amps worth of power, even at 12 volts, to be available at the track, without isolation?

Hobby transformers are isolation transformers where the primary and secondary windings are electrically isolated.  There is no electrical connection to the track.  

Using a Variac (trade name for variable voltage transformer) on the 120v side of a step-down isolation transformer delivers sine wave power.  A rotary light dimmer is will do the same but delivers a chopped wave.  Back in the pre-Z4000 days when our ZWs couldn't deliver enough power, many of us built power supplies this way.  I believe the ROW 400 used variable-voltage transformers in front of step-down isolation transformers.

There are a lot of step-down transformers of the "auto-transformer" design where the primary and secondary windings share the same wire.  A lower cost way to build a transformer.  This means your track is connected to house wiring.  A shock risk.  I considered re-using salvaged computer UPS step down transformers but all that I tested were the auto-transformer design.  I suspect the old car charger probably has an auto-transformer inside.

Note that Variacs, are auto-transformers.  NEVER use one connected directly to the track.  Always put an isolation transformer between the Variac and the track.

Add up today's cost of variable-voltage transformers, step-down isolation transformers, and circuit protection, and you'll find its easier and cheaper to buy the power supplies offered by the train manufacturers.

MARX / LIONEL / HIGH CURRENT / 50 AMP DC TRANSFORMER / AUTOMOTIVE BATTERY CHARGER & LAMP DIMMER - YouTube

check it out..!

OMG

Are battery chargers designed to work reliably at voltages less than 120V?  Notice the comments were turned off.

Paging Professor Darwin...

Rusty

Don't do it.  The train may run, but very soon you will be buying a new charger for your auto.

I use a Variac and a step-down transformer, but I also have circuit protection at both ends.  I agree - buy a used model train power pack.

"Whatever floats your boat!"

Why did you want DC?? 

For me my Prewar lionel 256 dual motors  runs so smooth quiet and with very little throttle compared to A/C

There is no such thing as a “DC Transformer.” The fact that the YouTuber uses that term repeatedly should tell you something about his level of electrical knowledge.

For me my Prewar lionel 256 dual motors  runs so smooth quiet and with very little throttle compared to A/C

Just get a full wave rectifier on Ebay for $5 or so and install it in between your Lionel transformer and track.  You will have DC  (pulsed).

@Arthur P. Bloom posted:

Yeah...what they said.

I hope I don't incur the wrath of the "power strip police" police by saying it, but using any electrical device for an application that it wasn't designed for is not a good idea. Not illegal, not a code violation (well, maybe it is) but definitely not smart.

Do you really want 50 amps worth of power, even at 12 volts, to be available at the track, without isolation?

Arthur you made a very wise reply. Any auto type  battery charger with a start cycle is designed to fire into what is essentially a dead short [the starter]. Some thing could go wrong and youve no way of quickly stopping it.

@DanssuperO posted:

MARX / LIONEL / HIGH CURRENT / 50 AMP DC TRANSFORMER / AUTOMOTIVE BATTERY CHARGER & LAMP DIMMER - YouTube

check it out..!

The skeleton sitting in the corner should be your first clue to run……and but fast ….😳

Pat

@Rich Melvin posted:

There is no such thing as a “DC Transformer.” The fact that the YouTuber uses that term repeatedly should tell you something about his level of electrical knowledge.

For sure Want to thank you for the BAKER gear demo. I always had this cloudy kinda blurry idea of what was going on in there, your demo really cleared that up. Thanks again. Charlie