LED Dimming ?

Submitted: Wednesday, May 19, 2010 at 23:44
ThreadID: 126583 Views:2080 Replies:4 FollowUps:1
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Has anyone used dimmers on their LED lights?

I have great bedside lights which were installed by BT. The only problem is when one of us wants to read and the other wants to sleep they're just too bright.

Has anyone know about dimming them or alternatively rigging some sort of adjustable shading on the lamps.

BT tell me they haven't done this.

Regards, Nigel.

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Reply By: GoinThere - Thursday, May 20, 2010 at 18:50

Thursday, May 20, 2010 at 18:50
Hi Nigel,

We have used a "blue" plastic leaf you can buy from a newsagent - A4 size, and cut it in a spiral shape which can be held over the LED light buy glueing some velcro so as to be able to attach/remove as needed. Still provides a good reading light while giving off a soft blue glow outside.

Terry
AnswerID: 580478

Reply By: Boystoy - Friday, May 21, 2010 at 01:03

Friday, May 21, 2010 at 01:03
Hi Nigel,

You must have good eyes, or else there has been a vast improvement in LED's in the past few years. Most people complain that they are not bright enough.

LED's output brightness is a function of voltage. If you want to make a simple regulator (dimmer) the construction is very simple & the parts are cheap.
You need to make a trip to Jay-Car, Dick Smith or Tandy & purchase a 317T adjustable regulator (about $2), a 220 ohm resistor, a 2000 ohm potentiometer, and a suitable knob. The lot should cost about $5-$6.

The ‘input’ pin of the 317T is connected to +12v. The ‘output’ pin is connected to the 220 ohm resistor and to your LED. The other end of the 220 ohm resistor is connected to the top terminal of the 2000ohm potentiometer. The bottom terminal of the potentiometer is connected to -12v (ground). The centre terminal of the potentiometer is connected to the ‘adjust’ pin of the 317T.
Pin connections of the 317T are; looking at the device face up, pins left to right are ‘adjust’ ‘output’ ‘input’

This is about as simple as you can get, have a go even if you have never played with electronics before. At worst you are only risking a few dollars, & it won’t go ‘Bang’. The staff at the store will also help with pin identification and any other help you need.

Good luck

Neil
A Bushtracker (or BT) is a "Boys Toy"

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AnswerID: 580479

Follow Up By: Motherhen & Rooster - Friday, May 21, 2010 at 10:06

Friday, May 21, 2010 at 10:06
Hi Neil

I find the direct bright light from the LED much better for reading. As my office light gets duller with the years, i now have a small LED desk lamp beside the computer - and i can see again! Our first LEDs in the bedside lamps were from BTi in cool white (bluish) and a very direct beam so it only lit up part of the page; i could cope with this and it didn't disrupt the other wanting to sleep. We have fitted warm white spreaders in the rest of the van and find they give a good natural light; much better.

Motherhen
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Reply By: Deleted User - Friday, May 21, 2010 at 10:48

Friday, May 21, 2010 at 10:48
Search ebay for item number 280504861024.

LEDs are current dependent devices and require a variable current controller to vary the light output. The ebay item above does not say how it works but I assume this would be the case. A variable voltage device will only work on a LED that has a resistor in series for current limlting.

Most LED lamps assemblies these days are current limlted which allows them to be connected to a wide range of voltages. This has the added advantage of being more efficient with less heat loss.

Our van is entirely lit by MR16s flush mounted in the ceiling. The bed lamps are also MR16s and are just warm to touch. A lot of them are required for good light distribution but are functionally excellent.

Unlike fluros you can guarantee they work every time. I do have fluros for external lighting as I have not found a suitable LED alternative.
AnswerID: 580480

Reply By: Lost and Frowned - Friday, May 21, 2010 at 19:09

Friday, May 21, 2010 at 19:09
I'm amazed and very appreciative for the ingenuity and expertise you've provided.

Not only very helpful but educational as well.

It looks like next trip I might avoid the, " aren't you going to sleep tonight gibe'.

Thanks again for your help.

Regards, Nigel.
AnswerID: 580481

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