one-touch window DIY possibility?

[enildeR]

bmwman91, no doubt you're good with electronics. I was wondering if you'd be inclined to devise a schematic for a one-touch module that we could solder up ourselves? I know that there our modules out there that could be bought for 50 or more dollars, but wouldn't it be cheaper to build ourselves? I was thinking along the lines of using relays (could we get away with one relay per window?) and a current sensing circuit to disable the relay. I'm not sure exactly what relay we'd need, but I thought a latching relay would work best. What are your thoughts?

I'm asking this because I landed up getting one-touch window switches without knowing it. I didn't want take them back and get the white-base switches that I need because they're double the price I paid for the green-base switches, so I would rather put that money into building a one-touch module. Sometimes I really wish I had a one-touch feature.

At least we can have a discussion started on the topic. If no one wants to help, I'll take on the task alone, and hopefully put a HOWTO up for everyone to benefit from.

Any input from others that are good with electronics are most welcome. I'm new to the forum, so I'm not familiar with whom is an electronic guru.

Thanks in advance.

Cheers!

[Zoso]

There are many, many ways to do this project... but here are two to get your mind started:

Focus on using a flip flop with some glue logic (ands/ors/xors/etc).  The flip flop will hold the value that it is given (say down), and then the surrounding glue logic will tell the flip flop when to reset (stop pressing down) or cancel if you don't want the window to go up all the way.  I believe the 74LS family are 12V tolerant (I think the window switches/motor is 12v?).  Discrete chips like those should be very inexpensive.  (something like $.25 each)  

Another way to do it is to use a CPLD... but I think this way would be more expensive as you'd need voltage regulators and some sort of level conversion (level shifters or transistors)... but this would give you ultimate control of the windows (and sunroof) and would be a tiny system.


I've often though of designing and selling small electronic gizmos like this... but never got motivated enough to do it.

[thumper3ld]

There are many, many ways to do this project... but here are two to get your mind started:

Focus on using a flip flop with some glue logic (ands/ors/xors/etc).  The flip flop will hold the value that it is given (say down), and then the surrounding glue logic will tell the flip flop when to reset (stop pressing down) or cancel if you don't want the window to go up all the way.  I believe the 74LS family are 12V tolerant (I think the window switches/motor is 12v?).  Discrete chips like those should be very inexpensive.  (something like $.25 each)  

Another way to do it is to use a CPLD... but I think this way would be more expensive as you'd need voltage regulators and some sort of level conversion (level shifters or transistors)... but this would give you ultimate control of the windows (and sunroof) and would be a tiny system.


I've often though of designing and selling small electronic gizmos like this... but never got motivated enough to do it.

I think you should motivate yourself cuz all that up there was klingon to me. :confused:

[D. Clay]

I hate the Ferengi! They're sneaky little weasels. Right now I'm watching a Mary-Kate and Ashley movie. Now that's science fiction. As to the all the way down switches, my first thought is to steal one. I stole almost every good idea I ever had! Get a switch and a whatever from an E36 if they have them.

[Zoso]

I think the one touch functionality in the E36 is located in the window motor unit.

[enildeR]

I thought it was all connected to the ECU? At least that's what I saw on R3V, and thus the main reason I posted on here. Maybe I'll run to the dealer tomorrow and see what I can find.

[enildeR]

Another way to do it is to use a CPLD... but I think this way would be more expensive as you'd need voltage regulators and some sort of level conversion (level shifters or transistors)... but this would give you ultimate control of the windows (and sunroof) and would be a tiny system.

How expensive are we talking about?

[Zoso]

I estimate it'd be under $20 for a CPLD, mounting board, voltage regulator, and several level shifters - probably closer to $15.

[bmwman91]

I have seen people swap the E36 switches in.  I am pretty sure the one-touch functionality is within the switch.....some sort of magic if you ask me.  The Bavarian Wizards did not imbue our window switches with this magic back in the day.  Perhaps they felt it best for us to not have this ability for some reason...or to help improve the chincy E36 interior.

[bmwman91]

Eureka!

http://www.strictlyeta.net/technical/e36switches.html

Again, I am pretty sure the switches have the one touch ability integrated.

[mrjezza]

bmwman91, don't mean to be a party pooper but the article says:

"The one-touch switches have completely different wiring, and will not work."

[ak96ss]

Autoloc WC1000, one for each window, $37/ea from http://www.performancedepot.com/productdisplay.html?sku=99404&hdwt=31101&loc=101&dealer=, perhaps cheaper on eBay.

[bmwman91]

bmwman91, don't mean to be a party pooper but the article says:

"The one-touch switches have completely different wiring, and will not work."

Haha crap.  Yet another reminder that I must read things completely.

[D. Clay]

Found the money url:

http://www.mesaperformance.com/web_store/web_store.cgi?page=bmwcat/onetouch.html&category=yes&cart_id=

[Zoso]

Found the money url:

http://www.mesaperformance.com/web_store/web_store.cgi?page=bmwcat/onetouch.html&category=yes&cart_id=

Holy crap - $40 each if you want lighted buttons.  That'd be $200 to do a sedan  with an electric sunroof.