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I'm confused, I think I ask this every year, but this year I will write down the answer . I'm using Variable Output. My Z1000 puts out 20ish VAC. I measured it, I don't remember and now the wiring is buried under Mt Crumpett.... So

 

 

Even set to 5V, the minimum output is 9.3VAC. At 22 Vout, it reads 20VAC. Why is the minimum 9.3? It is the same on both outputs and precludes running my old Lionel, or a trolley, below breakneck speed. If the answer is " Thats what it does", I will power it with an 80W Atlas next year and dial down the V Max on the Atlas. 

 

Again, I couldn't find last years answer, or anything in the DCS Companion or Manual.

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Marty,

 

is the 9.3 volt output being measured at the track or is it the setting on the DCS Remote?

 

Regardless, the actual track voltage will be x/22 of the input voltage to the variable channel, where x is the is what is set on the DCS Remote.

 

This is discussed on page 128 of The DCS O Gauge Companion 2nd Edition.

Last edited by Barry Broskowitz
Originally Posted by Barry Broskowitz:

Marty,

 

is the 9.3 volt output being measured at the track or is it the setting on the DCS Remote?

 

Regardless, the actual track voltage will be x/22 of the input voltage to the variable channel, where x is the is what is set on the DCS Remote.

 

This is discussed on page 128 of The DCS O Gauge Companion 2nd Edition.

Barry

Thanks. Edited rest of this out, as it was my misunderstanding of Voltage and not a "problemm"

Last edited by Marty R

 

I agree with you Marty, 5 volts is just tooo much for some engines and with a brick there's not much you can do about it.  You might be better with an old post war (fuse it) Lionel transformer for that channel.

 

This is my personal opinion.... I don't trust the MTH bricks  circuit breaker wise. Tooo many posts like your over the years.

Originally Posted by Gregg:

 

I agree with you Marty, 5 volts is just tooo much for some engines and with a brick there's not much you can do about it.  You might be better with an old post war (fuse it) Lionel transformer for that channel.

 

This is my personal opinion.... I don't trust the MTH bricks  circuit breaker wise. Tooo many posts like your over the years.

That's what led to my  post. Even at a setting of 5, I get 9

 

Originally Posted by RJR:

You need a lower voltage input.  Cutting the voltage that much in a TIU or similar device alters the wave form too much. 

 

 

 

RJR - I will use an Atlas 80W transformer. I wish I had tested it before I buied the plugs under mt Crumpet. I only have enough room now to reset breakers

"Voltage" can have several meanings when applied to an AC circuit, where votlage and amperage are constantly changing in strength and direction.  Normal AC derived from commercial power (even through a basic transformer) is a sine wave.  Normally the "root mean square" ("RMS") voltage is given, whicvh is much less than the peak voltage.  In another thread, gunrunnerjohn says that "Peak voltage is about 1.4 * RMS voltage."  In Wikipedia, { http://en.wikipedia.org/wiki/Root_mean_square } the formula for a pure sine wave is given as RMS voltage equals the peak voltage divided by the square root of 2.  But if the wave form changes, then the effective voltage is altered.  Cf the Wikipedia article for more discussion.

 

Another web site with an explanation is  http://www.nuffieldfoundation....-voltage-and-current 

 

Googling or Binging "root mean square"  will produce many explanations, but the bottom line is that ince the wave is distorted from a pure sine wave, things happen.  Solution, as I noted above, is to minimize the distortion by reducing the number of volts the TIU must drop the voltage.  Most (apparently not the Lionel CW80) transformers do not alter the sine wave form when changing the output voltage.  Controllers do.

 

When the wave form is other than a pure sine wave, your voltmeter may become of questionable accuracy.

Part of the discrepancy may be from the DMM.  The TIU "chops" the sinewave to adjust (lower) the voltage.  Many hobby-grade DMMs are confused by the irregular waveform from the chopped TIU output.  There have been many OGR threads discussing this.  If you care to study this further, search for threads with the exact phrase "true RMS".

 

While it appears you have a solution using a different voltage input, another method that works is to drop the voltage at the TIU output using diodes.  Yes it's a clumsy method, but as pointed out earlier, when you chop an AC signal too much to get a lower effective voltage the final waveform starts to look fairly ugly which can confuse some electronics.  Using external diodes to lower the voltage arguably does not distort the waveform as much as chopping it.

Thanks guys, These explanations make sense. At full output, no chopping, my Fluke 287 (def not hobby grade   reads 22ish. but at 5, TIU distortion exists. I want to use the DCS hand held, but i'm starting to wonder if a simple MTH IR controller might not be simpler for a Christmas layout. it's fun to keep changing it up.

 

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