Cupboard Door/Limit Switches

[Charles Smith]

Hi

I am looking to fit a few limit switches to a few of my internal doors in the house - ie, under stairs cupboard, small storage cupboards etc.

What I want is for a light to come on automatically when the door is opened, and turned off when the door is shut.

I seem to remember a limit/limiter switch will do the job, but I can't find anywhere online that sells what I am looking for or how to actually do it!

Does anyone have any advice on how I could do it?

Thanks

Charles

[Andy Hall]

Yes.

I've used part no. 456-4643 from RS Components for this exact job. Web site is

These are a good quality microswitch by Burgess with a decent cover and are adjustable.

You simply arrange it as a switch for the light. This version turns the light off when the plunger is pressed.

.andy

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[Lurch]

On 7 Jul 2004 12:09:07 -0700, charles_smith [e-mail] (Charles Smith) strung together this:

One of the last two on the page.

Does anyone have any advice on how I could do it?

Screw switch to door, wire switch to light as you would a standard light switch.

[pjdesign]

> >Does anyone have any advice on how I could do it?

How do you know if it works? Baz

[Andy Hall]

Why wouldn't it?

In my post, I described the use of a Burgess adjustable switch, which RS sell.

I know that that works because I have done it.

.andy

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[pjdesign]

I know it should work. But do you know if the light goes out? Baz ;)

[Dave Plowman (News)]

Stick the kids in there and wait for the screams.

[Andy Hall]

I see. Clever guy.

Two ways.

I could put my video camera in the cupboard, or I can listen for the click of the switch.

.andy

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[BillV]

No normal door is lightproof so you will see some light around the frame if its on.

[Owain]

"pjdesign" wrote | I know it should work. | But do you know if the light goes out?

Well, duh.

1. Drill a hole in the cupboard door. You can see if the light goes out.

1. Put a light dependent resistor inside the cupboard. Run the wires out. Measure the resistance.

2. Put the solar panel of a sun-powered plant rotator inside the cupboard. Run the wires out. If the plant rotates, the light is not out.

1. Wire a 12 volt pilot lamp in series with the 240 volt lamp in the cupboard. (Choose the wattages so both lamps take the same current.) Ask your electricity supplier to increase your transformer tapping to 252V. The pilot lamp will go on and off with the main lamp.

2. Put an ac milliammeter in series with the lamp in the cupboard.

1. Put a clamp meter on the supply cable to the cupboard lamp.

2. Turn off all the other electrical appliances in the house and watch the electricity meter. The wheel should stop revolving if the lamp goes out. (If the meter's in the cupboard in which you're fitting the light, you'll have to take a torch with you to see that the wheel has stopped when the lamp goes out.)

1. Wrap the supply cable to the lamp round a reed relay and wire the reed relay to one of those little speech recorder chips so that the device announces that the light has gone out.

2. Find a small child that's scared of the dark. Put the child in the cupboard. Listen for screams.

Owain

[Lurch]

On Thu, 8 Jul 2004 09:43:57 +0100, "pjdesign" strung together this:

Same way you know the fridge light goes out, shut the door from the inside!

[Dave Plowman (News)]

After a fair bit of looking, I couldn't find a really neat way of doing it, so ended up with a burglar alarm reed switch feeding a low voltage relay via a transistor. Makes concealing the cables rather easier when they aren't mains ones, and the interface can be sited anywhere convenient.