radio on until door opens

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=90684
Printed Date: April 27, 2024 at 11:20 PM

Topic: radio on until door opens

Posted By: graymae
Subject: radio on until door opens
Date Posted: February 19, 2007 at 8:53 PM

i would like to install this feature on my 96 bmw 318ti. I have this as a factory feature on my 03 olds silhoutte, which it turns off after like 5 mins or with the door trigger. I would like to set it up th same way on my bmw to turn off in about 5 mins or with the door trigger, whichever comes first. Does anyone know how to wire this up?

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Replies:

Posted By: hotwaterwizard
Date Posted: February 19, 2007 at 9:41 PM

https://www.the12volt.com/relays/page5.asp#drto

Radio On Until Door Opened (Retained Accessory Power)

If you wish to keep the radio (or any other device that is powered by an accessory circuit) on until a door is opened, you can do so by creating a latch when the accessory is turned on with the relay shown below on the left, then breaking ground to the latch when a door is opened as shown with the relay below on the right. While this will keep the radio on, the entire accessory circuit will see 12V+ until a door is opened with the key in the off position.

posted_image

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

Posted By: graymae
Date Posted: February 19, 2007 at 11:32 PM

Thanks, but i already know how to do this part, i just need a diagram to show how to add a timer to this setup so if i dont open the doors right after turning the car off, it will turn off within like 5 mins or so.

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Posted By: graymae
Date Posted: February 21, 2007 at 12:47 PM

How could i tie in a 555 timer into that setup to control the relays, which inturn keeps the radio on for a about 5 mins if the door doesn't open but still turns off with the door trigger?

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Posted By: hotwaterwizard
Date Posted: February 22, 2007 at 8:16 AM

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

Posted By: hotwaterwizard
Date Posted: February 22, 2007 at 8:20 AM

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

Posted By: graymae
Date Posted: February 22, 2007 at 4:51 PM

ok, on the first diagram with the 555, the reset and the trigger are interconnected. Could i connect the reset to the door trigger instead? On the relay (SPDT) side is were i get a bit confused. What do i do with 85, 86, 30, 87, 87a on the relay, where do i connect them? Couldn't i just use the 555 by itself to keep the radio on for a maximum of about 5 mins if the door does open but connect the reset of the 555 to the door triggerof the car, which would turn the radio off when the door opens?

Posted By: hotwaterwizard
Date Posted: February 22, 2007 at 9:41 PM

The 555 can not handle much power it needs the relay.

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

Posted By: graymae
Date Posted: February 23, 2007 at 11:13 AM

ok, so how do i connect the 555 to the relay? where do i connect 85, 86, 30, 87, 87a? I understand how to setup the 555 to power the relay, but i don't know how to cnnect the relay to the 555. thanks

Posted By: dualsport
Date Posted: February 24, 2007 at 1:09 PM

Updated:

You could try something like this-
Uses a transistor to switch the relay on or off-
When the ignition is turned off, and no longer supplies the 12V to the transistor, the cap holds the voltage needed to keep it on.
The cap starts discharging through the resistor, and when it drops below the voltage threshold of the BS170 transistor, the relay will turn off.
If the door is opened, it instantly drops the voltage across the cap down to turn it off.

A drawback is that the relay is energized whenever the ignition is turned on; it could be modified so it only comes on once the ignition is turned off, but it'd need some extra components. Figured it'd be simpler with this setup, if that's not a concern.

posted_image

The other option is to just use the first setup with the relays, and just try not to fall asleep in the car- :)

Posted By: hotwaterwizard
Date Posted: February 24, 2007 at 8:27 PM

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

Posted By: graymae
Date Posted: February 24, 2007 at 9:53 PM

dualsport, what are the extra parts needed to make it only turn on after the ignition goes off?

Posted By: graymae
Date Posted: February 24, 2007 at 9:58 PM

hotwaterwizard, could i connect the reset output to the door trigger instead of how its setup now and S1 is where i would connect it to the ignition wire right?

Posted By: dualsport
Date Posted: February 24, 2007 at 11:57 PM

To make it turn the relay on only after the ignition is turned off, you can use the following extra parts: CD4013 D flip flop ($0.50), a CD40106 Schmitt inverter ($0.49), another 10M resistor, 1uF cap, and a diode.
You can look at mouser.com for all the parts.

Posted By: hotwaterwizard
Date Posted: February 25, 2007 at 1:22 AM

S1 just gives a ground to reset.

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

Posted By: graymae
Date Posted: February 25, 2007 at 8:35 PM

hotwaterwizard wrote:

S1 just gives a ground to reset.

So where would i connect the door trigger to shut it fh the door opens?