LCD lights work only one direction ????

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roya
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LCD lights work only one direction ????

Postby roya » Sun Jul 24, 2011 9:38 am

Hi can anybody tell me how to wire up LED lights i want to use these to show that a section of track is live but it will only work in one direction when i change the direction the light goes out any ideas please

jus
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Re: LCD lights work only one direction ????

Postby jus » Sun Jul 24, 2011 10:02 am

LEDs by their very nature only work when the current flows in one direction, hence their symbol in electronics diagrams. To have a light that shows if the track is live in either direction, your best bet is to remove the LED and put in a standard bulb. You could wire in a small device to switch the current if you wanted to, but it would be a fiddly process, and not 100% reliable as the more components you use, the more there is a chance of failure.

If you wanted to show the direction of travel on a given section, then LEDs are perfect. Just wire one up the way you have, and then wire the other in reverse. This way you can tell which direction you will travel.

Hope this helps
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peroni
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Re: LCD lights work only one direction ????

Postby peroni » Sun Jul 24, 2011 10:18 am

The only other easy way is to use Bipolar leds (Red/Green), it will light up green in one direction and red in the other direction.

A bipolar LED for general indication and other purposes. These LEDs have a standard 3mm body with two leads, but contain two LEDs back-to-back. When the LED is connected positive to the long lead, the red LED lights, and when connected positive to the short lead, the green LED lights.
You can buy these in a variety of colour combinations, red/green, yellow/green, red/blue, red/green etc.

http://www.rapidonline.com/Electronic-C ... -LED/29341

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Flashbang
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Re: LCD lights work only one direction ????

Postby Flashbang » Sun Jul 24, 2011 10:44 am

roya wrote:Hi can anybody tell me how to wire up LED lights i want to use these to show that a section of track is live but it will only work in one direction when i change the direction the light goes out any ideas please

Hi
There are two basic methods of wiring indication lights....
One of them can only be used if your layout is DCC. Here the rail power can be used if wished to illuminate the appropriate LED on the mimic panel.

The more convention method and suitable for both dc and DCC too, is to use a point motor operated change-over switch, such as the Peco PL10 motor with a PL13 change-over switch fitted onto it.
If the points are operated by surface mounting motors such as the Peco PL11, then a small Microswitch can be used and is placed on one side of the point so as its actuating arm in pushed in by the points moving tie bar (Stretcher bar) as the point move over.
Then which ever type of switch is used and via its change-over contacts, the LEDs are fed.

There is some ideas on wiring of both switch operated and DCC powered indication LEDs on this web site... Link to conventional wiring If you're not take directly to the item, use the sub menu at the top of the page and select 'Mimic Panel Indications'.

For DCC then this page item will help.... DCC point indications Again if you're not taken directly to the item, use the sub menu hyperlinks 'Point Indications on DCC '.
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roya
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Re: LCD lights work only one direction ????

Postby roya » Sat Jul 30, 2011 8:14 pm

Many thanks for your input I’m going to try a grin of wheat bulb and see how that works not to sure how bright it will be ???????????????

locoworks
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Re: LCD lights work only one direction ????

Postby locoworks » Tue Aug 09, 2011 10:19 am

would feeding the LED through a rectifier work??


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