I need relay to hang for an extra 2 sec
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=86167
Printed Date: April 28, 2024 at 3:10 AM
Topic: I need relay to hang for an extra 2 sec
Posted By: porschemaniac
Subject: I need relay to hang for an extra 2 sec
Date Posted: November 25, 2006 at 9:51 AM
I am using the grounded mute wire from a handsfree kit to trigger a relay. Basically 86 gets 12V switched and 85 gets the mute wire. My need is to get the relay to be sluggish so it hangs for 1-2 seconds or so. I realize I could use a timer circuit, but is there any quick and dirty way to get the relay to not chatter so much (my cell phone drops the mute several times while initiating a call, such as between rings, and this is very annoying). Any suggestions really appreciated. I know how to put a cap across the coil to get the relay to drop out after a short while - but is there any way to sort of do the reverse and make the relay think it is still grounded at 85 for a little while even though the mute has gone high for a second? Porschemaniac
Replies:
Posted By: master5
Date Posted: November 25, 2006 at 6:07 PM
The chatter seems to me like feedback from the relay coil. did you try a "quenching" diode yet? Put the cathode (stripe) on 86 and the anode to 85. Now this will not prolong it but it will drain the coil and hopefully prevent the chatter. Let me know. -------------
Posted By: porschemaniac
Date Posted: November 25, 2006 at 6:28 PM
Thanks very much for the response. Yes, I do have a diode across the coil. It is not really "chatter", but dropping out of the relay for a second when the mute wire repetitively goes high between rings. It is an issue with the bluetooth kit and phone - but i'd like to solve it at the relay by having a 1-2 second hold on the relay coil. Any ideas?
Posted By: master5
Date Posted: November 25, 2006 at 7:02 PM
Instead of putting a cap across the coil..try putting it on the mute wire with a resistor (rc circuit). I do not know the values off hand but it should cause a delay you desire once the right values are used. -------------
Posted By: porschemaniac
Date Posted: November 27, 2006 at 8:45 AM
A sample circuit on how to do this would really help me. Thanks.
Posted By: master5
Date Posted: November 27, 2006 at 2:54 PM
https://www.the12volt.com/installbay/forum_posts.asp?tid=84785&PN=1 If you read through this thread it will give you some ideas and other links to building RC (resistive/capacitive) circuits. Lots of good info there but it might take some experimentation. If it helps keep in mind a relay coil draws aprox. 150 milliamps @ 12v, that might help as a starting point to determine the delay time length. Caps and resistors are cheap enough so buy a bunch and knock yourself out. Good Luck -------------
Posted By: hotwaterwizard
Date Posted: November 30, 2006 at 8:58 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: November 30, 2006 at 9:03 PM
------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: Ween
Date Posted: November 30, 2006 at 9:58 PM
hi, isolate the phone kit mute wire from your relay with a diode, 1N4001 (band towards phone kit). add capacitance across the coil of the relay. the value you add depends upon the several factors (resistance of the coil, drop-out voltage). if it's a bosch or equiv., i'd start with around 1000uF and adjust from there. 25 Volt rating should be fine. the relay should remain energized for a brief period of time even after the mute lead goes high. hope this helps mark
Posted By: master5
Date Posted: November 30, 2006 at 11:28 PM
Post back if you try either one with the results, I am curious.
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Posted By: ss-installer
Date Posted: December 01, 2006 at 9:00 AM
the last bluetooth kit i put in just ran betweenn the radio and speakers. it muted itself, didnnt even need a mute wire. Parrot brand kits usually come aftermarket color coded on speaker leads.
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Posted By: porschemaniac
Date Posted: December 01, 2006 at 9:29 AM
Fabulous suggestions! I tried the simplest - an electrolytic across the coil (+ side of electrolytic to + side of coil) and it works! I only had a 220uf handy but am geting about a half second with a miniature relay. So I'm looking forward to trying a bigger value. ss-installer, you are quite right about the Parrot kits. They have a built in mute switcher which cuts the headunit audio and substitutes Parrot audio - very slick. But for this install with Bose amp I'm using a special harness from www.parrotkits.com which has a black box that requires using the mute line. It is no fault of their harness that the Moto phone drops the mute from high to low several times while initialting a call. Their differential converter box works great by attenuating Parrot audio before sending it on to the amp. If anyone installs Parrot kits, their harnesses are the way to go.
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