single positive pulse to constant on/off?
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=125166
Printed Date: May 15, 2024 at 5:53 PM
Topic: single positive pulse to constant on/off?
Posted By: james82
Subject: single positive pulse to constant on/off?
Date Posted: December 20, 2010 at 4:14 PM
I'm looking for the cleanest way to take a single positive pulse from the OEM alarm/central locking system to toggle power additional sensors and warning LEDs etc.
The pulse is provided when doors are locked, and unlocked. I want to toggle the power to other devices from this. I believe this can be done with a single relay? But I can't find a latching relay that does this apart from one made by VW which they used in early cars to switch between dipped and main headlight beams.
I would like to use the least amount of relays etc and I would also like to keep drains down. I believe the wiring diagrams shown on this site so far requires the relays to be constantly energised for them to work?
An advice welcome!
Thank you.
Replies:
Posted By: oldspark
Date Posted: December 20, 2010 at 6:16 PM
Posted By: hotwaterwizard
Date Posted: December 20, 2010 at 8:40 PM
------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: December 20, 2010 at 8:55 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: December 20, 2010 at 8:57 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: oldspark
Date Posted: December 20, 2010 at 8:58 PM
But that's 2 buttons!
Otherwise I would have provided the normal SPST latching relay wiring.
(It can follow the input power, else an optional switche to engage, or an optional switch to break. The same topology as your SCR diagram except with an SPST relay...)
POST EDIT - the same as your 2nd diagram with a single relay; though I include diodes towards 86 to prevent cross-powering (instead of the otherwise redundant relay in the last 2-relay version).
That circuit is often used to limit switches - eg, water level systems.
Posted By: hotwaterwizard
Date Posted: December 20, 2010 at 10:22 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: December 20, 2010 at 10:29 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: james82
Date Posted: December 21, 2010 at 2:47 AM
Oh wow lol... I was thinking more along the lines of a mechanical latching relay!
Posted By: oldspark
Date Posted: December 21, 2010 at 2:58 AM
The problem is the single input/switch.
Two switches is easy.
Posted By: james82
Date Posted: December 21, 2010 at 3:24 AM
Isn't this a mechanical latching relay that only requires one pulse to alternate?
Posted By: oldspark
Date Posted: December 21, 2010 at 4:11 AM
I think so - it's the "standard" VW/Porche hi/lo relay.
Posted By: howie ll
Date Posted: December 21, 2010 at 11:13 AM
Why not a cheap simple OMRON latching relay, available from R/S here or Farnell and probably Mouser in the US, you have 1 and 2 pole changeovers, you can feed either a constant 12volts or ground and switch the other side of the coil via - lock triggers (or of course vice versa), will give you a constant pos or neg going on way when car is locked an going a different way when unlocked with no battery drain.
-------------
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: body80
Date Posted: January 14, 2011 at 8:43 PM
DEI relay.
I've used in with an aux out from my car alarm to trigger strobes. Pulse it once turned the strobes on pulsed it again and it turned them off.
Google Pulsed latching relay
https://cgi./DEI-611T-12-VOLT-ACTIVE-LATCHING-SWITCH-RELAY-TIMER-/140333447156#ht_2711wt_905
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