Restricting Xfmr Output for Childrens Interactive Layout?

Don:

Our club here in the Atlanta area sets up a kids layout at various shows throughout the year.  The layout has four tracks / trains in operation with four CW 80 transformers, one on each corner.

We tried different methods to limit the maximum amount of power each transformer could send to the track and the best was to install a small potentiometer on the back of each transformer.  This allows us to adjust the maximum power level very easily.  We've used this method for about three years now and surprisingly, the kids still haven't figured it out.

Curt

You can power the transformers with a Variac or a light dimmer. One Variac, although expensive, should power two or three transformers.

juniata guy posted:

Don:

Our club here in the Atlanta area sets up a kids layout at various shows throughout the year.  The layout has four tracks / trains in operation with four CW 80 transformers, one on each corner.

We tried different methods to limit the maximum amount of power each transformer could send to the track and the best was to install a small potentiometer on the back of each transformer.  This allows us to adjust the maximum power level very easily.  We've used this method for about three years now and surprisingly, the kids still haven't figured it out.

Curt

Curt, it would be great to see a picture of how that looks and works. I am also looking at adding a similar feature at home for the Christmas layout for kids to play with. Thanks for the great idea. 

juniata guy posted:

Don:

Our club here in the Atlanta area sets up a kids layout at various shows throughout the year.  The layout has four tracks / trains in operation with four CW 80 transformers, one on each corner.

We tried different methods to limit the maximum amount of power each transformer could send to the track and the best was to install a small potentiometer on the back of each transformer.  This allows us to adjust the maximum power level very easily.  We've used this method for about three years now and surprisingly, the kids still haven't figured it out.

Curt

Curt, That sounds fantastic!  Do you have any size of pot was used, I'm thinking 10k, 2watt.

Thanks,  Don

I never let the kids near any transformer controls, always worry about the risks if they get into the wires.

I have 7 LionChief engines with remotes.

I bolt then down to the fence with photos of the engines they are running with a plastic bracket to keep them from turning the speed control too far and breaking it ( from experience)

Using the LionChief remotes allows them to run trains without touching any wires.

I power the tracks from Transformers and set them so the trains will not run to fast when the kids turn the LionChief remotes to full throttle.

Here is my latest set up but similar to what I attach to the fence for several shows each year. Click on photos for a larger view. Wood either side of the LionChief controller and screws on sides to keep them from shifting, zip straps to hold them in place. Room to slide a screw driver down the side to turn controls on and off. I have the sound buttons covered as when kids have all 7 trains with bells on drives you nuts. And they cannot tell which engines have sounds. I have a little sound engine in front of each controller if they listen close and push top of train they hear all sorts of sounds from that train.

Another option would be to use "Beep" locomotives which have built in speed limiters. It doesn't matter where the kids push the throttle to, a "Beep" will not exceed 35 scale MPH. I've also pulled the boards from some worn out Beeps and installed them in old Lionel starter set 4-4-2 locos and gotten the same speed limiting. Which was good for my grandkids when they were younger.

Don / Pete:

Our club Christmas party is tomorrow and I'll be seeing the fellow who came up with the idea of using the pot meters.  I'll ask him to give me a drawing and a parts list and post them on here afterwards.

Curt

On the store display at Henning's Trains, there is a screw in the side of the CW-80 to limit the throttle travel.  Easy to install, and very effective.

If you have TMCC and a ZW-C or L you can limit the top voltage that way.  That's what I do at home to keep the kid run trains on the tracks.

I also recommend a Variac.  Plug your transformer into the variac and set input voltage to a level that works for output voltage... $64 at Amazon. 5A = 600W of control

I would use a variac on the transformer input side. There are many on the Bay for under 25 bucks. A 1000 watt variac will handle all of your transformers and supply them with pure sine wave AC, not chopped sine waves that most lamp dimmer give.

Pete

Pete,

The Variac is a good approach for a continuous application.  The specific situation I am trying to control will be at a county fairgrounds facility, and will have a total of 12 single tracks with trains.  The transformers planning on using are small inexpensive ones, and conventional engines only.  And, only be in place for 2 1/2 weeks.  So cost is a factor.  I think the pot on the output would be best if I get the correct rating.

Don, one high power pot will likely cost more than a single used variac and you will need one for each transformer. Then you have the heat factor. Variacs are very efficient and waste very little power. True a new variac would be very expensive but there are hundreds of used one out there.

How close are you to Van Nuys? There is an eBay seller there that sells refurbished items and lists many variacs. I have purchased a few lab power supplies from them. Very reliable.

Pete

You don't have to spend a ton of money on a Variac, look in the right places:  eBay - 111840786061 for $44.99 and free shipping.

Don,

A pot(entionmeter) is usually used as a volume control in an amplifier, etc.  It is a low current device.  A typical radio shack pot will carry a watt or two.  A rheostat is usually associated with controlling higher currents.  They are significantly more expensive when you get above 10W (which will control less than a 1 amp train or burn up trying!)

Another option would be an adjustable wirewound resistor (google it).  But again, they get expensive for higher loads.

In the long run, two of the variacs I pictured would probably cost less! And as mentioned above, the transformers you use will be getting a nice pure sine wave to plug in to, so any transformer should work well, (just at a lower voltage in which will result in a lower voltage out.

Ed

Another thought.  If you're using Z-1000 type transformers, don't use the supplied brick.  Instead, use a (fused) heavy duty 12V AC transformer.  The Z-1000 will get 12V in instead of 18V, so the top output will be about 2/3 of normal.

ps. see what happens when you type S-l-o-w-l-y!

GRJ,

Reminds me of the one I had as a kid, when I played with my electric "projects".  I like the amazon new one for a few bucks more, and it has a meter!

In case it matters to you word on the street has it that Eddie Van Halen uses a Variac for his guitar amps to give them that "brown" tone.

Pete

I'll agree with the use of the variac.  You'll likely only need one to power all 12 of your transformers.  Just make sure you don't plug anything else into the 'turned down' power strip.   For dead simple and cheap, however a mechanical stop may be the way to go.  

A bit more complex route, if you were so inclined, and using engines with can motors, might be to open up the locomotives and add a string of diodes on one of the lines to the motor.  this would leave any lighted cars and such to keep getting full power while slowing the locomotive.  

TP,

I for one, find that very interesting!

Ed

Hmmm,  by reading between the lines, it appears that one or two variacs would suffice.  Not 12!  Then the Variac becomes feasible.  That definitely sounds like the best approach.  (I did type this slowly, but it doesn't help my poor punctuation.  : )  .)

I think the variac is the way to go.  I also like Ed's suggestion of the new one on Amazon, it is a nice looking unit.

One of these (500w) variacs would power 12 40W train transformers. Two would power 12 80W transformers (roughly).  I would get two. 

I agree with two, I think that would be the safe option.  You don't risk any overloads that way.

Don, Give David Riddle a call. See the ebay link above. Tell him its for the kids and holiday layout. I'll bet he would cut you a deal.

Pete

Don / Pete:

I have pasted in the instructions provided by our club's "Train Doctor Ted" who added the pot meters to our kid's layout CW80 transformers.  I've also attached a photo of the pot and wiring.  If you have questions, I will be happy to pass them along to him.

Curt

Procedure for installing an electronic 'governor' to the throttle on a CW-80 transformer.

Purchase a 100K potentiometer at 1/2 watt; same approx. physical size as the transformer's throttle pot.  The pots's shaft should be approx. 3/8".

Remove the shell of the CW-80.

Unsolder the 'RED' wire off the transformer's throttle pot.

Solder a 6 inch wire to the throttle post that you just removed the 'RED' wire from.

      New Pot

On the 'new' 100K pot, short the middle post to one of the end post and connect the 6" (Blue) wire to these 2 posts.

On the 100K pot, connect the 'RED' wire to the other end post of the 100K. (You will need to extend the length of the 'RED' wire.)

Install the 100K pot in the back of the transformer shell to the right of the transformer's power outputs.  Make sure that the position of the pot does not interfere with reinstalling the shell and the wire connections of the pot does not touch any internal transformer parts.

Doing twelve of these as opposed to plugging in a couple of variacs seems like a really easy decision!  By the time you modify twelve transformers, you have hours invested...

Not mention it seems specific for CW80s. Do we know what the transformers are?

Pete

That's a good question. What transformers are they?

With the variac, it doesn't matter.

I like the C80 mod, will use that for another application.  Think will go with the Variac, talked with David Riddle, and that will work out great.  He is relatively close to me as well, will probably be able to will call.

As far as the types of transformers......  the display will consist of 6 G-Scale using MRC xformers, 3 O-Scale using various Lionel older xfrormers, (LW, KW, 1031), and 3 HO/HO-3 tracks.  (not sure of those.)

THANKS so much for ALL yours guys help!  Hopefully someday I will know enough to pass it on.  Really appreciate this forum!

I think the kids (and adults) will get a much larger charge of actually using the transformer controls to run the train and modulate the speed, etc.  Have ing a push button to run a canned sequence gets pretty boring very quickly.  You're also creating a lot more work wiring horn and bell buttons for twelve tracks!

IMO, the KISS principle is in play here, a couple of hidden variacs to limit the maximum voltage, and the controls on the transformers function as designed, job done.

Pardon my electrical ignorance: the variac puts less than 120 v. into the transformer, so the output becomes less than say the 20 v max.(if a ZW) ? So you have to experiment to find the voltage to adjust on the variac to get the desired output from the ZW?

I thought some transformers have the ability to adjust max voltage output.

The max output on a KW can be limited to 0-14 volts by wiring the common to the 6V pin.

BANDOB posted:

Pardon my electrical ignorance: the variac puts less than 120 v. into the transformer, so the output becomes less than say the 20 v max.(if a ZW) ? So you have to experiment to find the voltage to adjust on the variac to get the desired output from the ZW?

 

Bill,

It's all proportional.  If you have a train transformer set to put 16 volts on the track with it plugged into the usual 120V outlet, when you turn the outlet voltage to 90V (using a variac) the track gets only 12 volts.  The variac reduced the input to 75%, so the track gets 75% of what it would get at full power in.

Ed

gunrunnerjohn posted:

I think the kids (and adults) will get a much larger charge of actually using the transformer controls to run the train and modulate the speed, etc.  Have ing a push button to run a canned sequence gets pretty boring very quickly.  You're also creating a lot more work wiring horn and bell buttons for twelve tracks!

IMO, the KISS principle is in play here, a couple of hidden variacs to limit the maximum voltage, and the controls on the transformers function as designed, job done.

I kind of figured that pushbuttons would also have the added advantage of being easier and less expensive to replace from overly rambunctious use that kids (or even adults) could bring into the equation with the controls.  It's a little more costly to replace transformers that end up getting their handles broken.