stickman007

DIY "no-slam" Circuit?

20 posts in this topic

Posted (edited) · Report post

A few years back, Leadwing gave me a broken MDC "no-slam" module that basically opens the window ~1" when you open the door, and then close when you shut the door - therefore preventing the need to slam the door hard. I was never able to reverse engineer what they had and gave up. Lately I'm motivated to try again as I'm about to get another smart car! Rather than trying to figure out what MDC did, I wonder if we can just design our own like the EGR emulator circuit as a community.

 

I'm not trained in electrical engineering by any means...my degree is in Biology, but here's what I've come up with to start. Anybody wants to chime in?

windowscircuit.jpg

 

 

Edited by stickman007

Share this post


Link to post
Share on other sites

Love the idea, always wanted one for a coupe.... not as needed in a cabrio from experience. Steven from smartieparts sold a couple back in the day.

Share this post


Link to post
Share on other sites

AUGH......that reminds me of my old college days in electrical engineering....sorryI flunked out after they introduced AC and told my brain it couldn't use the picture of water running through a pipe, I need a mental picture  to fully get things into my concrete skull at times...lol

The idea is a simple one, it's the time your 555 timer operates to not over tighten so to speak your window...? OR will it open it and close it the same every time...?  Not a bad starting point that's for sure.

 

Share this post


Link to post
Share on other sites

I still have two in my coupe.  Both are working just fine.  I'm not the genius who made or installed them, but they are a nice thing to have.  Included is an "express down or up" when the window button is tapped lightly.

Share this post


Link to post
Share on other sites

The "one touch" feature I'm not sure how to do...almost seems easier to use an Arduino or Raspberry Pi. This way, its is even programmable or maybe bluetooth communication for updating? Rolling down windows with your phone on a hot day? Unfortunately, I don't know anything about programming either. Good project idea though...

Share this post


Link to post
Share on other sites

Posted (edited) · Report post

Any photos of the MDC unit?

 

I would expect the MDC unit utilizes a PIC microcontroller  and relays.

 

You would need 2 inputs, 2 outputs. i/p door open/close and window down switch, o/p window down and window up. 

 

With a 3rd i/p you could do an auto window down if you unlock/lock the doors several time within a set period of time.

 

One issue with the added relays or a microcontroller is an extra constant power draw.

Edited by Huronlad

Share this post


Link to post
Share on other sites

I don't think I even have that unit anymore...it was coated in a thick layer of epoxy, so I wasn't able to trace the circuit.

 

Just had an idea for the one-touch feature is to use a delay latch circuit that's self powering after the trigger...but it too has to be limited by the 555 timer monostable setup for around 4-5sec. This feature can be added into the circuit once the no-slam is finalized... Using microcontrollers is a good idea...will probably save a lot of unnecessary complexity, but others with more hardware programming experiences will have to take the lead.

 

I will make a detailed schematic including the 555 timers and posted it up.

 

 

Share this post


Link to post
Share on other sites

Why not use a capacitor and resistor on the relays to create a delay same way an electronic blinker works, just keeping it simple.

Share this post


Link to post
Share on other sites

Doing that will likely cause the relays to "chatter", could lead to premature failure of the relays and the window operation would not be smooth.

Share this post


Link to post
Share on other sites

Posted (edited) · Report post

No-Slam Circuit v1.jpg

 

I'm sure some of the relays can be eliminated with transistors, but I'm not sure how to do it properly. Diodes and fuses will probably be needed in a few places.

I only did the windows up side...windows down will be exactly the same, but on the 87 pin on the 1st relay.

 

Edit: made a mistake on R10k near pin 7 on the 555 timer...should be R1k (otherwise it will output for 5s instead of 0.5s)

Edited by stickman007

Share this post


Link to post
Share on other sites

Posted (edited) · Report post

I would wire the first 1A relay directly to the 555, so the timer only powers up when needed,  The extra relay/transistor does not really serve any purpose.

 

I can not recall , is the door switch either floating or connected to ground?  SAM polls to see 0V and then knows the door is open or closed?  Or is there current flow when the switch is connected to ground?

 

The up and down buttons, do they run directly to the window motor or are they just signals for the SAM?  If they just run to the SAM, 1A relays or smaller may be sufficient.

 

Edited by Huronlad

Share this post


Link to post
Share on other sites

Power goes directly to the motor after the last relay...I don't think there's any wires that goes to the SAM for windows.

 

Yes, eliminating the 1st relay would save a bit of complexity, but how would the the windows down be powered/triggered? (I still need to do some testing - I just assumed that the door switch grounds whenever the door is closed...it could easily be the other way around). Constant power to the 555 timer circuit would not draw much amperage...

 

I am looking at maybe learning raspberry pi or look into PIC micro controllers...

 

I found the original no-slam circuit in my tool box yesterday. It was not made by MDC, it was pinhead that made it - has his email on it. His circuit does seem to use a micro controller. There's a chip that has 14 pins on it that I can't identify.

 

Share this post


Link to post
Share on other sites

Was just research Raspberry Pi today...and I think you're right, it would be much more reliable, potential for expansion, and easier to program if I went with something like that. 

 

Well...I think right now, its just you and me brainstorming!

Share this post


Link to post
Share on other sites

Some folks have asked for photos.  Here are a few I took this morning.  Photo #7 is just to show relative size.  I down-sized them for the site, but full sized photos are available if anyone needs it

 

Smart no slam windows 007.jpg

Smart no slam windows 006.jpg

Smart no slam windows 005.jpg

Smart no slam windows 004.jpg

Smart no slam windows 003.jpg

Smart no slam windows 001.jpg

Smart no slam windows 002.jpg

2 people like this

Share this post


Link to post
Share on other sites

I hate electronics, but when someone does get this thing working please put my name on one...lol.   I give credit where it lies....anyone who lives in this world is head and shoulders above me, the local knuckle dragger...lol.

Thanks guys please stay on this....watching with eager anticipation....lol

The wife is going to destroy my car soon after she has to constantly reslam the door...lol pissed off is an understatement...lol

 

Share this post


Link to post
Share on other sites

I have to remind people when they get in or out of my smart or Honda ... "This is NOT an American car .. you don't  need to slam the doors!"

 

2 people like this

Share this post


Link to post
Share on other sites

I can relate....my 52 Willys had this same issue  and the wife slamed the door so hard she cracked the glass....just after it was finished....augh!!!!   It's such a pain to change it's been like that for years now...I dread having to get that glass out!  Not damaging the paint etc etc....augh!!!

 

Share this post


Link to post
Share on other sites

I think I'll will try and assemble one of my earlier prototype circuit...yes, it won't have the 1 touch feature, but I think the annoyance is the door slamming. Will report back when I get a chance to test...success or failure? (how bad can it be? Car burn down? hahahaha

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now

    Chatbox
    You don't have permission to chat.
    Load More