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Automatic Curtain drawing device!

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Grum

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Hi guy’s,

I have been trying to make a self-drawing curtain system, to draw the curtain’s in my flat for me when I am not there, kind of a burglar deterrent, so it looks as though someone is living there. Also it would be a really cool feature… But… when I came to actually put the thing together in my head and on paper, I find that I am ok with the mechanical side of thing’s but actually wiring the thing-up is baffling me. I realise that I am going to need relay’s etc… or would I need more!… really it is beyond me,:confused:... so I had this bright idea of asking you guy’s for help… What do you recon, anyone got any idea of how to go about it, making it as simple and safe as possible of course?

Basically I want the curtains to draw themselves automatically when it gets light in the morning and then draw themselves closed again at night.

I was intending to use two 12 Volt car window winder motor’s with gearbox (Built-in), as they seem to run very nicely and at a good speed, to do the actual drawing of the curtain’s, with a couple of micro switches on the rail, to signal when the curtain’s are either fully open or closed, as well as of course a magic eye, to indicate when it is getting light or dark. There would have to be some safeguard against jamming and overheating etc. Wouldn’t want to come home to find the fire brigade rescuing me neighbour above!
Although I mention using 12-V car window winder motor, I would like the device to be run from the household power supply.

Yours hopingly... with finger's n'all crossed :rolleyes:
 
Hi Grum,

running a simple curtain drive from a car window drive it is going to be real bulky.

Additionally you can't hook up a 12VDC motor to mains power supply of the household - if I understood correctly.

Here is an adjustable (for slow reaction) 12VDC dawn switch controlling a relay which drives the motor.

The circuit requires limit switches (NC) for the open and closed position of the curtain, to be connected to solder pads L1A - L1B and L2A - L2B which interrupt ground connection to the motor when the limit is reached.

The board is single sided and measures 57X37mm (2.24X1.44").

Boncuk
 

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I appreciate it defeats the fun of building your own BUT...

There are perfectly good curtain closing motors that run from the mains, can be run with a plug in timer or a light switch unit and have adjustable pressure "stop points" that stop the motor when the curtains are closed and also obviously stops the motor in the event of a jam. They are available left or right handed and small enough to hide behind the curtains when open.

just google "curtain motors", "curtain closing motors" or similar....granted they are NOT in some peoples "cheap" bracket but they are cheap considering the fit and forget peace of mind they provide. Trying to make one just seems too much hassle.
 
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Hi Boncuk,

Thank you very much for your very prompt reply and the diagram’s you sent me. Are these stock diagrams or did you actually sit and plan that out specifically? In either case, thanks very much. I apologise for not getting back sooner but thing’s got a bit hectic the last few days and I haven’t had a decent chance to reply.

I have had a look at your diagrams and to be honest I am having a struggle with trying to work it out by analysing it. I’m afraid I don’t really understand electronics, although always wanted to (The closest I get to it is car electric’s or repairing household electrical goods). I am looking at online symbol charts to try to see what the component symbols are and what does what but what with a chip involved as well, I have no chance really. All I can do is to build the thing and hope that it does the job but that wont be in the near future as I don’t even know where to source the part’s yet.

As for the car window motor being to bulky, as it is an all-in-one unit, it isn’t so bad and would hide behind curtain. I am sure I could find something more appropriate when I refine it later but for now I just want to get something working.
As for hooking the mains supply to it, I assumed that a rectifier (If that is the correct term) could sort out the current differences but again that is not the main concern at the moment, the main thing is to get it basically working.
You say that this is for “Slow reaction” “Dawn switch” … Can I ask what is reacting slowly exactly and when you say dawn switch, does that mean that it will only work one way e.g. only operate when it gets light. I want the thing to do all the opening and closing of the curtains totally unattended, will your circuitry do that?

I appreciate your help.
 
Hi Zipdogso,

Yes you are right, there are devices out there but they are expensive and I am not working at the moment and so that is why I want to try to build one myself, apart from also not liking being ripped-off and from what I have seen, that’s exactly what they are. Mind you, the ones you describe sound as though they simply draw the curtains for you, after you trigger them somehow, e.g. the light switch or timer, as you mentioned but for one they wouldn’t deal with the drawing open and closed, when I am away, at least for any reliable period of time but with a majic eye or light sensor etc it could. Besides yes, making it myself would please me ;-)
 
Hi Boncuk,

Thank you very much for your very prompt reply and the diagram’s you sent me. Are these stock diagrams or did you actually sit and plan that out specifically? In either case, thanks very much. I apologise for not getting back sooner but thing’s got a bit hectic the last few days and I haven’t had a decent chance to reply.

This diagram is a non-stock diagram.

I have had a look at your diagrams and to be honest I am having a struggle with trying to work it out by analysing it. I’m afraid I don’t really understand electronics, although always wanted to (The closest I get to it is car electric’s or repairing household electrical goods). I am looking at online symbol charts to try to see what the component symbols are and what does what but what with a chip involved as well, I have no chance really. All I can do is to build the thing and hope that it does the job but that wont be in the near future as I don’t even know where to source the part’s yet.

OK, lets take a look at the schematic:

As long as there is sufficient brightness the DPDT relay is not engergized meaning current flows via O1 - P1 (+12V) and O2 - P2 (ground) via the motor. If the motor reaches final position the connected limit switch between L1A and L1B should interrupt current flow. If dawn occurs the switching sequence is reversed powering the motor via S2 - P2 (+12V) and S1 - P1 (ground). Here again the current flow must be interrupted by the limit switch connected to L2A and L2B.

As for the car window motor being to bulky, as it is an all-in-one unit, it isn’t so bad and would hide behind curtain. I am sure I could find something more appropriate when I refine it later but for now I just want to get something working.

A geared toy motor would do, too.

As for hooking the mains supply to it, I assumed that a rectifier (If that is the correct term) could sort out the current differences but again that is not the main concern at the moment, the main thing is to get it basically working.

A rectifier will rectify mains voltage to 323VDC if mains voltage is 230VAC and to 160VDC if mains voltage is 115VAC.

You need a suitable transformer (15V secondary voltage, capable to supply enough current for the window motor (I guess somewhere around 5A), a rectifier and a smoothing capacitor and a linear regulator (LM317T with current boosting transistor) to make a reasonable DC-power supply.

You say that this is for “Slow reaction” “Dawn switch” … Can I ask what is reacting slowly exactly and when you say dawn switch, does that mean that it will only work one way e.g. only operate when it gets light. I want the thing to do all the opening and closing of the curtains totally unattended, will your circuitry do that?

Slow reaction is necessary in order not to have the curtain move if a passing cloud reduces light conditions temporarily.

I appreciate your help.

Welcome :) Just do the circuit as suggested with the PCB. Connect your curtain drive and it will work.
 
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I"m trying to make this circuit but am having some issues with it switching from one direction to the other. Can anyone tell me how long it is suppose to take to switch. Sorry I don't know a lot about circuits or how they work just like to automate things. Thank you
 
Hi tuke,

the circuit requires adjustment with the 500K pot to determine brightness and darkness.

You might try out the function by taking the pot to center position and shading the LDR completely which should cause the motor to turn in one direction. Exposing the LDR to light the motor should reverse.

If that works alright you should wait for real conditions (dusk or dawn) to switch the motor accordingly by turning the pot to the desired direction and position for the desired action.

For quick reaction short the electrolytic capacitor C2 (100µF) or simply omit it for testing.

Boncuk
 
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Thanks Boncuk,
i'll give that a try and see what happens. As of right now I can only get it to go in one direction. I'll keep you posted.
 
Not trying to make a pointless post but I made something similar out of lego (not kidding) when I was around 10 lol. Mechanically it was just a pulley system, geared down from a motor driving a loop of string, the string was attached to the curtains where they meet, one curtain attached to the 'top' bit of string (moving left to right) and the other curtain to the bottom string (right to left). The light sensor was nothing more than an LDR to a comparator, with hysteresis, so once it 'triggered' it closed the curtains, but one had to manually reset it to open them. Sounds horribly amateur (I was 10!) but it worked lol and the motor side of it was pretty small.
 
Thanks Boncuk,
i'll give that a try and see what happens. As of right now I can only get it to go in one direction. I'll keep you posted.

Hi tuke,

as a good method to find out the approximate trip point of the circuit I recommend measuring the dark/light resistance of the LDR you are using. The light resistance should be in the range of 5 to 15KΩ and the dark resistance several 100KΩ.

For a functional check short out the LDR to trigger the timer IC.

C3 may be reduced to 10nF.

Regards

Boncuk
 
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well I smoked it. shorted out the ldr and motor reversed but then puff of smoke. woops well I guess I'l start from scratch. I will make this work.
 
Hi tuke,

although you smoked it you know by now that the circuit works. You should check the output pin (3) for shorts (both to V+ and to ground).

Another possibility is too much current flow through the relay you used. Automotive relays have a very low coil resistance which might have caused more than 250mA frying the chip.

I also recommend to check the relay terminals for proper wiring. If the relay shorts the supply voltage you will also smoke your power supply.

Boncuk
 
Probably the relay it is an automotive type. I ordered some new parts and will make this work. I really appreciate all your help.
 
I would strongly recommend a transistor driving that relay. Even if the relays coil resistance is fairly high, the 555's 250mA output is an absolute limit.

Perhaps I am missing something, but what turns the motor off? As far as I can see, it just contorls the motors direction....
 
I would strongly recommend a transistor driving that relay. Even if the relays coil resistance is fairly high, the 555's 250mA output is an absolute limit.

Perhaps I am missing something, but what turns the motor off? As far as I can see, it just contorls the motors direction....

Hi Blueteeth,

modern relays (even power relays) draw a maximum of 40 to 60mA. So there is a fairly good safety margin for the timer IC.

There are four solder pads contained in the schematic (and also on the PCB layout). They are named L1A - L1B and L2A - L2B. Those solder pads should be connected to limit switches (NC) to open when the motor is supposed to stop.

Regards

Hans
 
Ok, finally received my new shipment of parts. Built another curcuit and it works like a champ. Now all I have to do is install it for the real test. Thanks Boncuk for all the help.
 
Hi Boncuk:

I made a curtain closer about 30 years ago before they were even on the market. Simple design. At that time I had access to a machine shop.

The drive was done by replacing some of the cord with ladder chain. Where the motor is mounted determines the working opening width. The closer to the floor, the wider the opening that's possible.

The drive pulley was about 2-3". Motor RPM needs to be about 20 and torque about 50 oz-in.

The motor I found on the surplus market did have an internal clutch. It was a 24 VAC bidirectional motor. It was mounted on the wall with a spring loaded mechanism. The motor could slide a bit to keep tension. If the limit switches failed the chain would come off. Nylon shoulder washers were used to guy the motor. The motor conviently had 3 mounting points.

So,that takes care of the drive. Alternate, more expensive methods would involve bead chain and a bead chain sprocket.

You could easily pop the chain off the drive if you had to move the curtain manually.

Now for the limit switches. They were triggered by triangular pieces of aluminum that were mounted on the traverse rod pulling gizmos. Attached to the wall was an adjustible microswitch, so a tiny amount amount of adjustment was possible for where the curtain stopped.

The power supply was a 24 VAC wall wart.

The control box had a manual and automatic mode. In the automatic mode, I used a timmer. Probably if I had to do it over again, I'd use a astrologigal timer.

It was simple and worked very well. I thought about light and a heat flux sensor. Ideally, you'dlike to base closing of the curtain on heat flux and desired temperature. Most people, however, don't like their drapes open at night.
 
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