switching problem

[Harry Bloomfield]

I have one which has been running for 15 months so far without failure.

Problem is the unit is battery powered and at the top of a pole. Reed switches need much less power.

[Owain]

You close the doors. The cupboard is in darkness. Note - the photocell is inside the cupboard. The light is *outside* the cupboard shining in (AIUI)

Owain

[Bolted]

That, and it is on a timer.

[Dave Plowman (News)]

But Bill says he's using a timer - and I assume an electronic one which would not have an inductive input.

[Bill Wright]

Yes, but this wasn't about the cupboards it was about the reed switches on the gates.

Bill

[Recyclist]

I'd assumed that the light would be in the cupboard! If the light is

*outside* the cupboard, then I'm afraid I think the whole idea is over- complex and a bit ridiculous. But if the OP does take your advice to fit a photocell, then a timer is pointless and wasteful. T

[Dave Plowman (News)]

Ok. But was the one you had problems with used within its rating? Any switch will fail if you exceed that. They're basically signal rather than power switches.

>

[Bolted]

The original post suggests the light will be outside, shining in. I may have read too much into that, but I am in the middle of installing something very similar with some directional ceiling spots which will come on when cupboard doors underneath them are opened. (I've gone for NO reed switches, in series, FWIW).

What difference does it make where the luminaire is - as long as the light gets into the cupboard.

Yes, if the light is outside, but not if the light is inside (because your point would otherwise apply!)

[Peter Watson]

Fit a security type PIR in the cupboard and take the switched feed out of it via the two door switches (wired in parallel) perhaps?

PIR then implements the timing period for you...

[mlv]

Hi Bill,

I haven't got time to plough through this thread right now, but have you resolved your light circuit problem?

It seems quite straightforward (your door switch contacts will have to be wired in parallel).

A simple DE (Delay on Energisation) timer is all you seem to need. No need for any relays.

What timer have you obtained (manufacturer and type/model number please).

What supply and voltage are you using (e.g. mains 230V, 50Hz).

I'll sketch you out a circuit over the next day or so and email it direct (if you have registered a valid email address).

[Dave Plowman (News)]

You need to read Bill's requirements more carefully...

[Bill Wright]

No. The cabinet maker has agreed to make the panel at the top of the unit removable, so I will be able to re-do the switches if neccessary, so I thought I'd see whether the present disadvantages matter in practice.

If they are in parallel, to start the timing period the supply (or trigger; it doesn't matter which) must be removed and then restored. So both doors must be shut and then one or both opened. That's OK unless you've left a door open and the timing period has ended when you want the light on. It means that you have to shut the door then open it. Ideally I wanted the light to come on if one door was opened, even if the other had been left open previously.

Well, it's a multifuntion timer from RS, set to Delay on Energisation.

Mains.

That would be very kind. You can email via the wrightsaerials.tv website.

Bill

[Toby]

Did you see my post earlier - surely that would work, wouldn't it?

Toby...

[John Rumm]

Give us the part number and we might have a fighting chance of designing something that does what you want!

[Bill Wright]

Sorry. I couldn't find it last night because we do the RS stuff on a different PC and the backing up had not been done that puts everything on this PC as well. 331 0928, set to function 421.

Bill

[Razoo]

Yes, as Dave Plowman implied, I had missed the requirement for the light to operate for the timed period when the second door is opened, despite the first door had been left open and the light having.already timed out.

It's a tricky little circuit. I assume that the door monitoring switches are single-pole normally closed, with the contact held open by the closed door(s)?

Are the door monitoring switches available with a changeover contact?

Can you post the RS Stock number? There are so many timer functions listed, it would be helpful to know what functions you have available.

I think that the most simple solution electrically (although possibly not the best solution financially) would be to use two interval timers (RS timer function 421 - On Pulse). These timers will work with the SPNC door monitoring switches you already have to give you the circuit logic you want. It's a very simple circuit using just 2 SPNC door switches, 2 interval timers and the light.

Would you still like a circuit sketched out to show the two interval timers, or is it obvious enough?

Suitable interval timers are RS Stock no. 160-262 (Tele Enya - Function Wu, £23.39), RS Stock no. 300-5913 (Broyce, £22.00) or RS Stock no. 330-6654 (Broyce, £19.60). RS Stock no. 300-5913 is a dedicated interval timer (i.e. not multifunction), and it is the one I would choose as it can't be accidentally set to the wrong mode.

[Dave Plowman (News)]

I don't think they are, either push to make or push to break - hence my idea of using alarm reed switches which are. But only if used to trigger an electronic timer due to low power handling.

You could fit more than one switch I suppose, but there's a danger of the rather strong springs making the door open.

[Andy Luckman (AJL Electronics)]

I have recently started playing with Microcontrollers (PICs). This looks like an ideal application for one, just a bit of easy software to knocjk up and it will do anything you ask. The 16F630 I use is under £2.00. Outputs will drive a relay directly and they can be battery powered if need be.

[Dave Plowman (News)]

Yes. I've got some literature and breadboards for these and I'm sure they'd do lots of clever things. Just need the tuits. Might be the answer to my 'fading' problem on another thread.

[Andy Luckman (AJL Electronics)]

Well I am still a beginner and by no means an experienced, but I have so far written four assembler programs into one controller, and it is all working fine (ish). It is for a pair of electric gates. We had a commercial unit but the software was terrible and wouldn't work logically for the customer's requirements. So I designed my own!

Feel free to call me if you wish and I might be able to give you some pointers.

To start off, I bought a PIC Kit 1 from Microchip. It comes with some PICs to play with and a set of tutorials. It also programs and tests them.

There is free development software which has to be run BillyGoat side on

inc debugging tools and a simulator. They give you a C compiler too, whatever that might be :-)

There is Acorn software available, but I found it was so close to Microchip assembler, it was better to use that and save £100!