Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Suggestions for turntable indicator lights.

3892 views
7 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    July 2004
  • From: Lewiston ID
  • 1,710 posts
Suggestions for turntable indicator lights.
Posted by reklein on Thursday, January 31, 2008 10:00 AM
I just finished a scratchbuilt turnatable and have used a decoder to power it and the MRC auto reverser to handle the polarity thing. Now instead of an indexing device I would like to have a light come on when the TT track is lined up with its leads. Any suggestions will be welcome. I was kinda looking for a simple contact on the TT to turn on the light, or perhaps at dwarf signal at each lead that comes on when the track is alined. Prototype usage is not necessarily required.
In Lewiston Idaho,where they filmed Breakheart pass.
  • Member since
    December 2004
  • From: Pa.
  • 3,153 posts
Posted by DigitalGriffin on Thursday, January 31, 2008 10:07 AM

How about having the light light up when the turntable isn't moving?  Would that work for you?

How many volts are you running through your turntable motor?

 

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

  • Member since
    July 2004
  • From: Lewiston ID
  • 1,710 posts
Posted by reklein on Thursday, January 31, 2008 12:32 PM
The TT motor is on 12 V from the decoder. I need the light to light up when the tracks are alined.
In Lewiston Idaho,where they filmed Breakheart pass.
  • Member since
    November 2007
  • 1,089 posts
Posted by BlueHillsCPR on Thursday, January 31, 2008 12:52 PM

Without seeing the application I would suggest as a possible solution using a roller lever switch mounted so that it would be tripped when the tracks align.  Another option would be to use an infrared detector circuit which might be more precise and easier to initially setup and adjust.

Just throwing ideas around. My 2 cents [2c]

  • Member since
    December 2004
  • From: Pa.
  • 3,153 posts
Posted by DigitalGriffin on Thursday, January 31, 2008 1:45 PM

 reklein wrote:
The TT motor is on 12 V from the decoder. I need the light to light up when the tracks are alined.

I think it's safe to assume that if the table isn't moving it's going to be aligned with some track.  So I think this circuit is what you are looking for.  It's about $1 in parts.  6 cents for the NPN transistor.  50 cents for the Full bridge rectifier, and about 40 cents in resistors and lights.

 

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

  • Member since
    July 2004
  • From: Lewiston ID
  • 1,710 posts
Posted by reklein on Thursday, January 31, 2008 2:47 PM
Nope,sorry. The turntable at this stage has no indexing whatsoever. You control the rotation of the table using the the digitrax throttle and it will rotate until you turn off the throttle. You align the tracks by eye. I want a light to come on when the tracks align. I'm thinking of an LED at each lead track that will light when a contact on the TT touches the leads to the LED. I need a stop distance of +/- 1/32". I'm trying to develope a system for a nearly blind freind who can see a small point of light across the room but cannot see details. Currently he has a Mickey Mouse indexing system that sorta works. Eventually he has to put his fingers on the TT to "see" if its aligned. Thankyou though for your contribution.
In Lewiston Idaho,where they filmed Breakheart pass.
  • Member since
    December 2004
  • From: Pa.
  • 3,153 posts
Posted by DigitalGriffin on Thursday, January 31, 2008 3:11 PM

 reklein wrote:
Nope,sorry. The turntable at this stage has no indexing whatsoever. You control the rotation of the table using the the digitrax throttle and it will rotate until you turn off the throttle. You align the tracks by eye. I want a light to come on when the tracks align. I'm thinking of an LED at each lead track that will light when a contact on the TT touches the leads to the LED. I need a stop distance of +/- 1/32".

oh...tricky...

Idea #1:

Just my suggestion but maybe you could use a tomar shoe (bronze phosphur on the bottom of the turntable.  You could then paint a line about 1/64" wide using conductive paint in the turntable pit to complete the circuit.  This would be the least favored way as you would have to line the paint up carefully...and I mean carefully.  You would also have to narrow the shoe to 1/64" wide.

Idea #2:

Line up the table using IRDOT sensors or photovoltaic cells.  This would require some electronics knowlege.  But upshot is you can adjust the placement of the sensor.  AND you could get the circuit to cut the power to the table once it lines up!  Sort of like a stepper motor.

 

 

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

  • Member since
    August 2006
  • 50 posts
Posted by yesterdaysradio1 on Thursday, January 31, 2008 7:00 PM

Hello,

   Search Turntable Drive. You will see the Geneva Drive that I built. One Micro switch can be added  that will trigger a light when the bridge is lined up. The Geneva Drive is very accurate. it is used to transport movie film. Hope this helps ypur friend.

 Jerry

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!