Speculative notion

[thor]

Reading about peoples experiences with power supplies and looking at the prices of some of the better ones makes me consider building my own. I just spent some time searching the web and you can buy some very nice hefty transformers and variacs for a decent price, might be better to roll my own, so to speak.

I prefer big low geared control knobs to those strange handles anyway and analog meters to digital ones, reckon it would be possible to build a bulletproof unit with all the bells and whistles for less than I'd have to pay for a model train one. Just an idea...

Years and years ago I had a German made controller my dad bought for me, it was a massive steel box about 9" cube with a big knob on it that my EE friend tells me was, in fact, a variac as against a resistance controller which he also tells me are pretty bad at low voltage settings because they limit the current too much (I'm not an electrical genius but I can follow a diagram).

I told him about the business of pure sine waves I read about here and he said that in that case use a variac with a voltage limiting stop instead and you'll never have to worry about not having enough power for the job. I dont know enough to really make sense of this so I'm still researching my options.

[Jumijo]

Thor,

You're already over my head! But good luck building that transformer.

Jim

[phillyreading]

Thor, have you tried a local train show or a model train auction? Buy an old 275 watt ZW and repair it, for me two or three ZW's have more than enuff power for any layout, if you are losing power to the far side of a layout add a set of parallel jumpers, sometimes depending on the size five sets of jumpers are needed & you can use a buss wire 14 AWG or larger due to voltage drop. A friend of mine says he powers every section of Gargraves track with hook-up wires and does not have a voltage drop any place on his layout.
I feel it would be safer to buy a power unit than build one. Also have you done price comparisons to see if you are saving money?
Lee F.

[BillP1]

Thor -

As long as you have a positive stop to guarantee that you will not be able to advance the voltage beyond 18 to 20 volts, I see no reason why your "variac" approach wouldn't work.

Don't forget to put an appropriately rated fast acting circuit breaker (or fuse) in series with the lead to the center rail.

----------------------------- Bill

[thor]

phillyreading:-As far as pricing goes

xfmrs offered me:-a 20 Amp unit 6.5" x 9" x 7.5" weighs 22 lbs and would cost $ 330 plus shipping..

[thor]

.

Don't forget to put an appropriately rated fast acting circuit breaker (or fuse) in series with the lead to the center rail.

----------------------------- Bill

Good advice Bill, thanks!

Like I said, I'm no expert but I'll definitely take advice on the safety issues and I'd use a GFI for sure. The reason why I wanted to build a monster was that the garden layout idea will soak up some power and I like to do things right the first time and not have to worry about them ever again which was Dad's approach too. That variac he bought me is probably still going, it lasted me 20 years of hard use and the only reason I don't still have it is I was living in England then and the voltage is different.

My POS Lionel controller that came with the train set (admittedly a bottom feeder) has been nothing but trouble and reading all the posts about controller issues was what made me think about the possibility of building my own.

However 20 amps is welding level power (well almost) so I'd want to make quite sure it was as idiot proof as possible since there's no isolated secondary winding on a Variac and a fault could conceivably make the lines go 'hot' with full power.

I was hoping for some feedback from some more knowledgeable types, thanks again.

[Anonymous]

Sounds to me like something a "Goober" would make to burn off his Kudzu patch, fire his still or burn down his hound dog barn![:D]

[Anonymous]

I would like to point out that a standard variac does not provide any isolation between the input and output. For safey. you must use a conventional stepdown transformer (18 to 24V secondary) between the variac and the train layout.

Daniel Lang

[ben10ben]

A variac controlling a secondary transformer would be the safest option. Just be sure you put a stop on the variac so that it doesn't go past 120 volts.

I think that you can find everything you're looking for in the Right-of-Way transformer made about 15 years ago. It is, I believe, 200 watts per chanel, has two great big control knobs, and an analogue amp and voltmeter for each ouput.

[Anonymous]

Ben
Have you been to West Jefferson,N.C. lately ? The site of a dontown mural depicting the N&W's "Virginia Creeper". I believe your Grandfather lived there at one time.

[lionelsoni]

Listen to Daniel. Don't use a Variac or Powerstat (both trade names) by itself. They are what is known as autotransformers, in which there are no separate primary and secondary windings, only a single winding. One end of that winding is the common. If it is not connected to the ground side of your power wiring, it and all your track is connected to the hot side. This is as dangerous as the DC reducers that Lionel sold before the war.

A typical Variac has a control range of over 120 volts in less than one turn of the handle. You would use only a smidgen of that anyway to control your trains. It would be very difficult to adjust.

The separate stepdown transformer that Daniel and Ben suggest will solve both problems, providing isolation and making the control range of the Variac useful.

[thor]

Thanks everyone for the advice. I like the sound of that Right of Way unit, who is the manufacturer? I found a couple of decent train controllers elsewhere during my searching but what I didnt like was their hardware - I dont like sliders and itsy bitsy little controls, I really wanted something with a big knob preferably low geared like radios used to have on their variable tuning capacitors.

I DO take advice from those who know more than I.

[ben10ben]

Thor,
The transformer of which I spoke was made by a somewhat obscure brass importer known as Right-of-Way Industries in the early '90s. They went out of business when the owner took deposits on an F-7 he was going to produce and then never delivered. He was also kicked out the TCA, by the way, over the same ordeal. The transformers, as well as many of their other products, turn up on Ebay from time to time.

[overall]

I used a Variac with an Lionel SW transfomer plugged into it. I then ran the wires to the track from the SW in the usual manner. I would set the SW to about 60 % of it's range and then controlled the voltage by turning the knob on the variac. It worked really well. It allowed me to run trains at slower speeds than I could have otherwise.

Never ever try to use the Variac directly connected to the track. Energizing Lionel track at 120 volts ( the top voltage on a Variac ) will smoke any trains sitting on the track and maybe cause a FIRE. It could SHOCK you if you were to touch it yourself.

George

[darianj]

If you have the know-how and feel confident...I say go for it. Sometimes doing it yourself gives the best satisfaction.

[lionelsoni]

Not that it will make any difference to the train, but a Variac or Powerstat can usually put out a little more than the voltage put in, like 120 volts in, 0-140 volts out. This makes them useful for correcting a power line's voltage to 120 when it is low as well as when it is high.