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Car Window Auto Drop & Raise

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Paulusx2

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Hi, total newbie to this site - hoping that I can get some assistance with a device I'm trying to put together.

Modern convertible vehicles have a device that drops the window 10mm when you open the door and raises it to the seal when you close it. I own an older convertible car which does not have this capability and therefore, the windows don't always seal correctly. When I was much younger I used to make simple electronic gadgets therefore, I thought I'd make a 'window drop module'.

Attached is the schematic that I have designed - I'm sure it's not very elegant so please be gentle..... I have tried to simulate the design on easyEDA but it doesn't appear to work. Before I blew the dust off my breadboard and invested in components I thought I'd try out this site for help.

In short, my circuit is built around two 555 timer chips. The hope is that these will provide me with an output for a set duration upon triggering. Presets R1 & R2 would be used to fine tune these durations.

The 555 on the left (labelled IC2) controls the drop of the window. When the existing door switch (used to switch the internal lights) closes it goes to ground triggering the 555 to provide an output to relays 2 & 4 for 0.5 seconds. This will be long enough for the window to drop approx 10mm.

The 555 on the right (labelled IC1) controls the lift of the window. When the door is closed the door switch opens causing current to flow from Collector to Emitter in TR1. This will trigger the 555 to put an output of 1.5 seconds to relays 1 & 3. This duration is longer than the drop signal as it needs to ensure the window is pressed against the seal. I have added R3 & C3 in an attempt to delay the lifting action to ensure the door is fully closed, This will ensure that the window won't start to lift before the door is completely closed.

SW1 is a reed switch that will be fitted inside the door to disable the device if the window is already down when the door is opened or closed.

The fuses are existing within the car and are primarily there to assist my integration into the car - assuming that I can progress the project that far.

As I said, it's been a long time since I last played with any electronics so I'm guessing there is a much simpler way to achieve my goal but I have hit the limits of my knowledge now. Any help or guidance would be very gratefully received.

Many thanks,

Paul.
 

Attachments

  • Window Drop Circuit v1.pdf
    28.3 KB · Views: 233
Is it ok to stall the window motor when the window is fully closed, or does the car have a limit switch which arrests the window travel?
 
Thank you for your reply. There are no clever electronics that senses the window is up and shuts down the motor off.
 
Looks ok, you might be able to do the whole thing with just one 555, but it probably isnt worth the effort they are not expensive.
I wouldnt fiddle with the reed switch, if the indow is allready down, operaing the motor isnt going to do any harm for 0.5 sec, ok with the window close timer being longer than the open eventually after a load of closes the window will be up, but thats not going to harm anything.

Beware if the battery is low it will take longer to open the window 10mm.
 
Thank you for taking the time to respond Dr Pepper. Good point about battery condition affecting the performance of this module. Also, weather conditions may have an impact (motor needs to work a little harder in the cooler weather).

Thanks to your positive comments I'm feeling more confident in my design and believe my failure to simulate on EasyEDA is probably down to my inability to drive the software.... Again, thank you for taking the time to respond.

Paul.
 
No problem.
Its a simple circuit, probably just as difficult to simulate as build.
Build it on breadboard and use a led as the winder motor.
 
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