First off I just want to say hey. I've taken circuit classes in college but never really applied the knowledge to real life stuff so I'm slowly making my way around.

My problem is this... my car has side mirrors that fold in and out but they are currently not hooked up to do so. They both have a (+) and (-) 12v wire and fold in or out dependent on which way the current flows. The trick is I want them to fold out when the car turns on and fold in when the car is turned off. I already have a relay to use which directs current one way when on and another way when off. This would work by itself if I didn't care about the motor being burnt up so i need SOMETHING that trips it when the mirrors are all the way out or all the way in and won't let them move until the reverse action is triggered... all of this with the turn of the key. Any help would be much appreciated. Thanks!

 

Do the mirrors have cutout sensors on them? If you run them out, does it stop and the current stop flowing? Also does it do that when you bring them in?

You could use a microcontroller that is timed to run them in and out. Use the ignition wire to signal when to run them in and out. But you would need a programmer to program the microcontroller. So you already have the relays setup?

You would need a regulator to limit the power to the micro, use a 12F675 (or 12C629) to a transistor to drive the relays.

Can you draw up what you have in paint and post it?

 

You need a microprocessor for that job. I tried to figure it out analog but it is too messy.

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The mirrors DON'T have cutout sensors on them... and I've been tempted just to try and add something to do that. So no, once they're out (or in) the current does not stop flowing.

I do have the relays but they are from another project so I'm not stuck to using them.

I'll draw something up in just a little bit but I'll go ahead and say that my problem lies in just getting the current to STOP flowing when they reach extension or rectraction. Something that would detect a voltage surge and trigger a relay would be ideal. Is there anything like that small enough for a car?

 

One option is a microcontroller, tie the ignition to an input (after you drop the voltage from 12 to 5volts of course), and have it software timed to drive the delays.

You did not fill in your location. This weekend if I have time I can draw it up for you. Practice for me in Eagle cad. Is this an add on to a car that came without the feature enabled on the car?

I just did a pic for a Range Rover, to add auto headlights ON via ignition.
The 2004 did not have the feature, the 2005 has it. We bought the 2005 switch and hid a microcontroller in to add that mode. Friend of mine comes up with all kinds of cool ideas like that.

Range Rover are odd cars but people in the States buy them.

 

Location added

A microcontroller sounds like it could definately do the trick but I have NO Earthly idea how to even begin use on one of those... I'm assuming that's what Eagle CAD has to do with? How much are microcontrollers BTW?

This is an add on to the car that did not previously have it, although there is an option for it from the factory. What brings me to knowing that this is possible without a microcontroller is that others who have added this feature simply needed a different window control unit and they didn't need to get anything reprogrammed. (i.e. - a circuit in the window control unit... which is fairly small I might add) But they also don't get what I'm trying to achieve.

 

ok, here's what I drew up. The switch is just a simple Radio Shack DPDT relay here:
http://www.radioshack.com/product/in...entPage=family

As I eluded to before, I believe this would work if I wasn't worried about the motors frying.

Attached Images

Mirror Circuit.JPG (17.1 KB, 20 views)

 

here it is, the relay is a simple DPDT 10VDC/10A plug-in relay from RadioShack. Like I eluded to before, I believe this would work (correct me if I'm wrong) if I wasn't worried about frying the mirror's motors... which of course I don't want.

Attached Images

Mirror Circuit.JPG (17.1 KB, 12 views)

 

If you can't make up your own solution, you could try a power window automation module, like the ones for alarm/autostart/etc.They will have a input for each direction, and sense current to protect/limit the motors.They are reasonably cheap off Ebay, just make sure you get one that does both directions (ie. up/down or in/out in your case)

 

great idea... could that work without actually pressing the button on the window automation module? And how come nobody knows what goes into that type of circuit?

 

There are no buttons on the module itself, it has inputs that can be connected to whatever you want.Inside the module is usually a microcontroller that does the current sensing and motor control.

 

So if I found one with an auto up AND an auto down I could use it and probably just use some sort of trigger to connect the pins? Say the trigger could be the door locks? How would I get the ignition to activate this?

 

Eagle cad is to draw a schematic and make the PCB layout. Pics are in the $75-1.50 range for what you are tring to do.

I have made many pic boards in the 1" x 1" range or less. Also, just solder a chip socket to the wires and plugged in the chips on some items. How small is small?

If you are trying to make just one see what the window module cost. If you are making many, the PIC/micro version will probably be cheaper, depending on the time you have to spend as well.

 

I'm just making one. So since I can find many window control modules online for less than $20 is that the way to go?

 

Why not just wire in a circuit breaker / Proxy switch that will trip when the motors current draw spikes from the motor hitting the end of its travel path?