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Would like to convert a DPDT switch

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=138764
Printed Date: December 06, 2021 at 5:41 AM


Topic: Would like to convert a DPDT switch

Posted By: swedespeed7
Subject: Would like to convert a DPDT switch
Date Posted: April 03, 2015 at 1:53 AM

Hi guys,

I'm kind of poking around in the dark here, but hopefully someone can help me out. Here's the deal:

I have a DPDT rocker momentary switch that controls a 12V motor. Press and hold the switch one direction, the motor opens a door until it's all the way open. Vice versa, door closes until all the way closed. Opening/closing takes about 3 seconds.

If the switch is kept depressed in either direction, the motor will continue to receive power and would most likely burn out eventually.

My goal is to convert the momentary rocker switch to a single push-button switch. For example, the switch is pushed and the motor operates until the door is all the way open. Press it again, motor closes the door all the way.

I'd like to accomplish this without having to modify the motor or door.

Is there a way to use relays to accomplish this? Something else? I'm somewhat familiar with the standard 5-pin relay but that's it.

If this is possible, what type of switch should I use?

Thank you in advance!



Replies:

Posted By: howie ll
Date Posted: April 03, 2015 at 2:43 AM
Use an SPDT sourced from ground feeding a pair of DEI 528t timer relays.
Often use this method for folding mirror control.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: swedespeed7
Date Posted: April 03, 2015 at 2:51 AM
Great, thanks. Can you go into more detail? Maybe a wiring schematic?




Posted By: howie ll
Date Posted: April 03, 2015 at 2:52 AM
Yes but later today.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: swedespeed7
Date Posted: April 03, 2015 at 2:53 AM
Great, thank you!




Posted By: howie ll
Date Posted: April 03, 2015 at 3:28 AM
Here you go:-motor_control.png

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: swedespeed7
Date Posted: April 03, 2015 at 10:36 AM
Thank you! So how exactly do these 528t relays work? Do they sense when the motor has finished opening? Or is it strictly a timer?

Will a single button momentary SPDT switch work?




Posted By: howie ll
Date Posted: April 03, 2015 at 10:42 AM
Adjustment pots accessible through the case, 1-90 seconds. You can see the relay contacts moving.
Method is to time the act of whatever you're controlling in either direction then add 1 second to each.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: swedespeed7
Date Posted: April 03, 2015 at 10:45 AM
howie ll wrote:

Adjustment pots accessible through the case, 1-90 seconds. You can see the relay contacts moving.
Method is to time the act of whatever you're controlling in either direction then add 1 second to each.


I see, that sounds perfect. And a single push button momentary SPDT switch will work for this? As in, I push the momentary switch once, the switch immediately releases, but the motor keep turning until open or closed position, correct?




Posted By: howie ll
Date Posted: April 03, 2015 at 10:50 AM
You need a momentary centre off SPCO (aka SPDT) as I explained a above. A single push button won't do it. You'd need two. If your existing switch is spring loaded centre off, i.e. momentary action, like a window switch then remove the power supply feed it from ground, remove the existing ground the outputs then feed the 2 X 528t.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: swedespeed7
Date Posted: April 03, 2015 at 11:12 AM
howie ll wrote:

You need a momentary centre off SPCO (aka SPDT) as I explained a above. A single push button won't do it. You'd need two. If your existing switch is spring loaded centre off, i.e. momentary action, like a window switch then remove the power supply feed it from ground, remove the existing ground the outputs then feed the 2 X 528t.


I see. So like a center off momentary rocker switch, correct?




Posted By: howie ll
Date Posted: April 03, 2015 at 11:24 AM
Exactly.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: swedespeed7
Date Posted: April 03, 2015 at 11:25 AM
howie ll wrote:

Exactly.


Thank you very much for your help!




Posted By: howie ll
Date Posted: April 03, 2015 at 11:43 AM
Here's a stylised diagram of how to rewire your existing switch, this makes it one touch either way. As I said before, this is how mirror folds and effectively one windows work.
Disconnect 12 V+ supply and rewire to the 528t's and ground (s), reconnect ground to 12V+ terminal, send outputs (originally to motor) to each 528t.:-
switch_mods.png

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: howie ll
Date Posted: April 03, 2015 at 11:54 AM
I've redone that diagram to make what you have to do more obvious:-2EF_switch_mods.png

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.




Posted By: swedespeed7
Date Posted: April 03, 2015 at 1:32 PM
thanks!!




Posted By: hotwaterwizard
Date Posted: April 03, 2015 at 9:37 PM

To convert the momentary rocker switch to a single push-button switch without having to modify the motor or door.
When Opening/closing takes about 3 seconds.
You could construct your own circuit.

posted_image



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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !




Posted By: rodsfromday
Date Posted: November 28, 2015 at 8:40 PM
hotwaterwizard wrote:

To convert the momentary rocker switch to a single push-button switch without having to modify the motor or door.
When Opening/closing takes about 3 seconds.
You could construct your own circuit.


posted_image



I am busy with autofold mirrors and was going to use the diagram howie suggested using the timers but I came across this diagram and found it much easier esp. with sourcing components.
The problem i now have is that after i energise the relay for folding, it takes forever for the capacitor to discharge in order for me to unfold. It probably wont matter if you leave the mirror folded for say a few hrs. My issue is if i accidentally activate the 'fold switch' side while mirror folded, then i have to wait for the cap to discharge before i could unfold them. Besides dead shortening the caps out, is their another way of increasing the discharge time pls?
TIA

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BMW Engineering





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