Fixed Voltage Question

[newt]

Using insulating track and fixed voltage from my KW, my Gatemen work fine.
However, I want to run my MTH K-4 utilizing an MTH Z controller (for the bell and whistle options), which has no fixed voltage option available. Is there any way electronically to get a fixed voltage to the Gatemen that is compatible with operating the K-4 using this MTH transformer? The voltage to run the K-4 at a reasonable speed isn't high enough to fully activate the Gatemen. Thanks for any help .

[phillyreading]

Unfortunately NO!  I don't think that you can do what is called phasing with the older transformer and the new transformer.

Use the KW to power the gateman accessory and the MTH Z controller for the train. Use a track contact device that is spring loaded and depends on the weight of the train to activate the gateman, the part might be a # 154C contact.

Lee F.

[lionelsoni]

My impression was that you didn't want to use the KW at all.  But, if using it to power the gateman, using an isolated control rail, is an option, go ahead and do it.  Connect the KW's common to the outside rails and its accessory terminal to the gateman, just as you had it when running the train from the KW.  It doesn't matter what voltage, waveform, frequency, or phase differences there are between the two transformers when used in this way.

Lee and I agree on one thing, that one of us doesn't understand electrical theory at all.

[bfskinner]

Lionelsoni said,

"...one of us doesn't understand electrical theory..."

That's cold, Bob, very cold. Accurate, but very cold. 

[willpick]

Newt, here's what to do: leave your gateman hooked up as is. Since you say they work fine, don't mess with them. I'm assuming you are using one of the accessory posts and not one of the two track power posts.

      Hook up the Z controller input to one of the track power outputs(A or B)/U. Run wires from the Z controller output to the track. Set the KW's output to 18 volts, then the Z controller will run your MTH engine--- you are just substituting the KW output for the Z's output.

HTH--

[newt]

Thanks HTH for the reply. I understand how your suggestion would work, but I'm currently using the KW to
power two other lines. ( I forgot to mention that in my original post ) Doesn't your reply assume I have a KW line available and not already in use?? Thanks again for any help.
Fred

[lionelsoni]

That's how I originally read your question, Fred--that you want to get the gateman to operate somehow using the new transformer without the KW's being involved.

Of course, one way to do it is to get some other small transformer and use it for the gateman.  Barring that, I can think of two other approaches that might work:

I don't know what is in the gateman accessory; but if it is simply a solenoid, you might be able to get more action out of it by rectifying the voltage in and running it on full-wave DC.  This might work because the reactance of the solenoid coil will not impede the DC current in the way it would the AC, leaving only the coil resistance to determine the current.  You might be able to increase the current further by about 40 percent by putting an electrolytic capacitor across the DC, to get the peak voltage instead of the average.  The capacitor size needed will depend on the coil resistance, but 5000 microfarads should suffice.

Another possibility is to reduce the track voltage, compared to the voltage used for the accessory.  A simple way to do this is to put modified bridge-rectifier modules in series with the center rail, but not in series with the gateman.  Use modules rated for about 5 amperes and wire the + and - terminals together.  Then connect modules in series by their ~ terminals.  You will get a little more than a 1-volt reduction for each module.  If the new transformer uses some kind of electronic waveform synthesis, this method may produce unpredictable results.

[phillyreading]

Bob N.

I am more into motor control and three phase transformers than I am into electronics, which deal with higher voltages than most people have in thier house, that is why I say to use the proper rated switches for the proper voltage source, hope that helps you! 

Have you heard of delta-wye-delta transformer hook-ups? That deals mainly with voltages over 240 volts and three phase power for A.C. commonly used in commercial and industrial buildings, example would be a cabinet shop or Home Depot store, where lighting can be 277 volts.

Electronics may have some differant current pattern issues that I am not aware of!  I have only a basic understanding of electronic circuits and the new stuff in electronics can be baffling to say the least, computer circuit boards constantly changing every five or six months getting smaller and more complex.

Lee F.

[willpick]

Fred, I thought you were using one of the accessory posts of your KW to power the gateman, but  I found out that the KW only has 2 accessory posts at 6 & 20 V, with a "floating" 14V between them. These won't run the gateman well--6V too little, 20V too much. I'd get a small PW starter set transformer or even a 1033/1044 as these will have the correct voltage to operate the gateman.

As to using your Z controller-- do you have the transformer and the controller or just the controller? If you don't have the transformer, I would think about getting one. they aren't that expensive-- they are available on Ebay for less than 40-50$ + shipping.

Hope this helps, keep asking questions!

[jchase1970]

Ok, I'll bite?  What is a Deltat-Wye-Delta transfromer?  I've hooked up Delta - Delta and Delta - Wye and Wye - Wye, but never a Delta-Wye-Delta. 

Delta - Wye, Lets see if your talking about 240 3-phase you'ld have 240 coming in on a Delta connection which is the 3 windings in a triangle config with no common connection to all 3 windings, then outputing a Wye winding configuration where the 3 windings share a common connection and is normally drawn as a Y with the center point being the common connection and should be grounded as well giving you 3- 120v legs in a 120/208V 3 phase panel as you have a  208v phase to phase with a power factor of 1.732 giving you 120v on each phase to ground.  Now you could have incoming voltages of 480/277 which is a wye connection and step it down to 208/120 or a line voltage of 2400 delta stepping down to 480/277 then sub disturbution  through 480 delta 208/120 wye transfromers.  This is used in most commericial locations

Now Delta - Delta is used only for stepping up or stepping down voltage.  You can have a 240v/120v delta panel but these panel have every 3rd breaker slot designed so you can't plug a breaker into them, this is because you have no common grounded refrence as in the Wye config.  The best you can do is ground 2 windings the 3rd winding to ground will give you a 'wild leg' voltage of about 180v but will have no current carrying capacity.  These are used mainly in large factories with a lot of motor loads.  This lets you use 240v 3 phase motors not 208v motor and you have less amp loading on your main electrical distrubition.

Wye - Delta are almost always used on high voltage lines commonly 4160v lines, 4160wye/2400v delta.

 

 

I'm not even going to talk about ac and dc switches you'll have to read up on electrical theory to understand why dc devices have higher arc currents then ac and thus why a dc device is much heavier then a ac device at the same voltage rating.

 

John 

 

 

[newt]

Thanks for the advice. Folks have been real helpful. How did we ever trouble shoot these
kinds of problems without this forum??