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Dimmer

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  • Member since
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  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Saturday, April 3, 2010 7:00 PM

 Probably got lucky then, they DO make dimmers for inductive loads that would work OK with a transformer, but the common kind sold for dimming incandescent lights is not going to work and will have the results mentioned above.

 I'd say use the diode method, it works well, is cheap and simple and nothing gets hot. I did that on an N scale layout I built a long time ago and it worked very well.

                                    --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
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Posted by jeffrey-wimberly on Saturday, April 3, 2010 3:58 PM

rudywa
Was the dimmer between power and transforer or the transformer and lights?

Between power and power pack.

Running Bear, Sundown, Louisiana
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  • From: Utah
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Posted by rudywa on Saturday, April 3, 2010 2:53 PM
Was the dimmer between power and transforer or the transformer and lights?
  • Member since
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  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
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Posted by jeffrey-wimberly on Saturday, April 3, 2010 1:46 PM

Mark R.
I'm thinking you got lucky - I would NOT recommend controlling a transformer with a dimmer !!!

Maybe I did get lucky. It was an older Bachmann trainset power pack and an analog type dimmer that worked with a potentiometer. I used it wired inline with the power pack for over a year without the pack even getting warm. All it did was supply current to structure lights.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
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beatus homo qui invenit sapientiam


  • Member since
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  • From: Brisbane Australia
  • 568 posts
Posted by Alantrains on Saturday, April 3, 2010 4:06 AM

 

yes you're right. I smoked a 12volt transformer by plugging it into a light dimmer. Lots of unpleasant smoke and a dead 2 amp transformer! Put your bulbs in series (2 at a time will halve the voltage) its much safer.

Alan Jones in Sunny Queensland (Oz)

 

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  • From: Ontario Canada
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Posted by Mark R. on Friday, April 2, 2010 6:35 PM

jeffrey-wimberly

 The way I did it years ago was to wire a lamp dimmer in line between the wall socket and the power pack I was using.

I'm thinking you got lucky - I would NOT recommend controlling a transformer with a dimmer !!!

All phase control dimmers are non-linear loads. A non-linear load is one where current is not in proportion to voltage. The non-linear load on dimming systems is caused by the fact that current is switched on for only part of the line cycle by a phase control dimming system. This non-linear load creates harmonic distortion on the service feeder. Excess harmonic currents cause conductors and the steel cores of transformers and motors to heat. Sometimes the heating of the distribution transformer can be a problem, because transformers are rated for undistorted 50 Hz or 60 Hz load currents. When load currents are non-linear and have substantial harmonic content, they cause considerably more heating than the same undistorted current.

You could be asking for trouble should sufficient heat builds up causing the core to break down. A definite fire potential would be at stake here !

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

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  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
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Posted by jeffrey-wimberly on Friday, April 2, 2010 8:29 AM

Doc in CT

 If you buy the "wall wart", double check the voltage with a meter.  I checked a 9volt the other day and it was pumping out 15volts !!

Many of the wall warts will put out a higher voltage without a load. The voltage indicated on the label is the voltage expected under load.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
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Running Bear Enterprises
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  • Member since
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  • From: Enfield, CT
  • 935 posts
Posted by Doc in CT on Friday, April 2, 2010 8:11 AM

 If you buy the "wall wart", double check the voltage with a meter.  I checked a 9volt the other day and it was pumping out 15volts !!

Co-owner of the proposed CT River Valley RR (HO scale) http://home.comcast.net/~docinct/CTRiverValleyRR/

  • Member since
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  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
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Posted by jeffrey-wimberly on Friday, April 2, 2010 7:00 AM

JoeinPA

jeffrey-wimberly

 The way I did it years ago was to wire a lamp dimmer in line between the wall socket and the power pack I was using.

 

Jeffrey:

That reminds me of an acquaintance who was using a variable transformer (Variac) set to 10 volts to power his lights.  He failed to lock down the adjustment knob and it got bumped and "migrated" to a much higher voltage with an interesting fireworks display from his pike.

Joe

I never had that problem. Being the careful fellow that I am I taped the dimmer knob in place so it couldn't be moved.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
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beatus homo qui invenit sapientiam


  • Member since
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  • From: Pittsburgh, PA
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Posted by JoeinPA on Thursday, April 1, 2010 3:06 PM

jeffrey-wimberly

 The way I did it years ago was to wire a lamp dimmer in line between the wall socket and the power pack I was using.

 

Jeffrey:

That reminds me of an acquaintance who was using a variable transformer (Variac) set to 10 volts to power his lights.  He failed to lock down the adjustment knob and it got bumped and "migrated" to a much higher voltage with an interesting fireworks display from his pike.

Joe

  • Member since
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  • From: Orig: Tyler Texas. Lived in seven countries, now live in Sundown, Louisiana
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Posted by jeffrey-wimberly on Thursday, April 1, 2010 12:42 PM

 The way I did it years ago was to wire a lamp dimmer in line between the wall socket and the power pack I was using.

Running Bear, Sundown, Louisiana
          Joined June, 2004

Dr. Frankendiesel aka Scott Running Bear
Space Mouse for president!
15 year veteran fire fighter
Collector of Apple //e's
Running Bear Enterprises
History Channel Club life member.
beatus homo qui invenit sapientiam


  • Member since
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  • From: Northern VA
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Posted by jwhitten on Thursday, April 1, 2010 9:18 AM

JoeinPA

jwhitten

 

Be careful not to burn your fingers!

(Or anything else-- that's asking for trouble if you're not certain what you're up to.)

I guess my problem is that I continually assume that people use common sense.

Joe

 

 

I find that, despite its moniker, common sense usually ain't.

 

John

Modeling the South Pennsylvania Railroad ("The Hilltop Route") in the late 50's
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Posted by JoeinPA on Wednesday, March 31, 2010 3:16 PM

jwhitten

 

Be careful not to burn your fingers!

(Or anything else-- that's asking for trouble if you're not certain what you're up to.)

I guess my problem is that I continually assume that people use common sense.

Joe

  • Member since
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  • From: Northern VA
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Posted by jwhitten on Wednesday, March 31, 2010 12:14 AM

JoeinPA

 The simplest way would be to place a high watt resister in series with one of the AC feeds.  The value (Ohms) of the resister would be determined by how much dimming you want.

Joe

 

 

Be careful not to burn your fingers!

(Or anything else-- that's asking for trouble if you're not certain what you're up to.)

Modeling the South Pennsylvania Railroad ("The Hilltop Route") in the late 50's
  • Member since
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  • From: Dearborn Station
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Posted by richhotrain on Tuesday, March 30, 2010 7:29 PM

Allegheny2-6-6-6

 No the simplest way is to go buy a wall wart transformer for about $10.00 in a lower voltage. If you are not 100% sure of what your doing with electricity it's best off you don't mess with stuff like that. The way my luck runs I would have the FD in my dirve way the next day drowning  my layout with a 2" line.

That's the way I would go too.   Why take chances if you don't know what you are doing?

Alton Junction

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Posted by Allegheny2-6-6-6 on Monday, March 29, 2010 10:02 PM

 No the simplest way is to go buy a wall wart transformer for about $10.00 in a lower voltage. If you are not 100% sure of what your doing with electricity it's best off you don't mess with stuff like that. The way my luck runs I would have the FD in my dirve way the next day drowning  my layout with a 2" line.

Just my 2 cents worth, I spent the rest on trains. If you choked a Smurf what color would he turn?
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  • From: Christiana, TN
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Posted by CSX Robert on Monday, March 29, 2010 11:32 AM
You could use multiple pairs of standard silicon diodes, each pair wired in parallel but with opposite polarity, and the multiple pairs wired in series with each other. Each pair of diodes would drop the voltage by ~0.7 volts.
  • Member since
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  • From: Ottawa, Canada
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Posted by jkeaton on Monday, March 29, 2010 10:05 AM

Or, put a diode in series with the lights, if half-voltage would do the job for you. One plus - no resistor heat to deal with.  Negative - only half-voltage as an option.  (yes, actually half-wave DC, but the effective power is half of the AC supplied)

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  • From: Pittsburgh, PA
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Posted by JoeinPA on Monday, March 29, 2010 8:35 AM

 The simplest way would be to place a high watt resister in series with one of the AC feeds.  The value (Ohms) of the resister would be determined by how much dimming you want.

Joe

  • Member since
    August 2005
  • From: Utah
  • 83 posts
Dimmer
Posted by rudywa on Sunday, March 28, 2010 10:46 PM

Any of you Electrical experts know how to take the 19v AC output on my power pack usually used for accessories, dim the output with a variable knob so the bulbs last longer, I use the DC on spare packs to dim lights but I would like to be able to do that with my 19v AC leads.

Thank You

Actually, I think I found a workarpund, many bulb types require different volts so I found these Cables Unlimited AUD-6000 that I can cut off the leads like Miller Engineering power packs, then I can select any one of 6 different voltages on the powerpacks to match bulb or less. -Thanks

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