latched on/off output
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=131940
Printed Date: May 01, 2024 at 8:12 PM
Topic: latched on/off output
Posted By: mr_malina
Subject: latched on/off output
Date Posted: August 03, 2012 at 3:35 PM
I am attempting to do the following relay setup. I am wanting to use a 12V+ ignition wire to activate the setup and for it to return to a off position after the ignition looses power. Is there a way to do that with this setup or would I have to add a additional relay to the ignition wire? Thanks
Replies:
Posted By: oldspark
Date Posted: August 03, 2012 at 7:39 PM
Yes - just use ONE relay that is energised (#86) from IGN +12V.
BTW - that is not latching. It is a typical relay circuit which is on when its control or signal wire is on.
Posted By: howie ll
Date Posted: August 04, 2012 at 12:58 AM
And if you do want to latch it see some posts below.
-------------
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: mr_malina
Date Posted: August 05, 2012 at 1:07 PM
Maybe I am thinking about this wrong, I will let know what I am trying to accomplish. I am installing OEM A/C in one of my vehicles that did not come with it. I want to be able to turn on the A/C with the push of a button and turn it off with a push of a button but only when ignition is on. I also want if the A/C is on when the vehicle is shut down when it is started next time it goes to off by default. It appeared to me that I could accomplish this with relay setup pictured above, but this is over my head. It would also have to have a positive output, prefer for positive input and not worried about switch.
Posted By: mr_malina
Date Posted: August 05, 2012 at 1:08 PM
Cant read apparently ^^^
Maybe I am thinking about this wrong, I will let know what I am trying to accomplish. I am installing OEM A/C in one of my vehicles that did not come with it. I want to be able to turn on the A/C with the push of a button and turn it off with a push of a button but only when ignition is on. I also want if the A/C is on when the vehicle is shut down when it is started next time it goes to off by default. It appeared to me that I could accomplish this with relay setup pictured above, but this is over my head. It would also have to have a positive output, prefer for positive input and not worried about switch.
Posted By: oldspark
Date Posted: August 06, 2012 at 3:15 AM
That's different to what you originally described.
How's:...?
That diagram's +12V should be IGN +12V so that it deactivates with IGN off.
The " +12V out" can be the aircon if that IGN +12V has enough current rating, though I'd probably recommend the 12V out feeds another relay (#86) that connects an appropriate or new fused +12V from the battery (#30) to the aircon (#87).
The second relay not only takes the load of the "latching relay's" IGN +12V, but also allows future signals to kill the aircon - eg, aircons often turn off at low revs or idle. IE - a low RPM signal could break the 2nd relay's GND (#85) or +12V signal (#86).
FYI - that diagram exists in various places, but the12volt's capacitor value for latching relay? 8th reply includes its wiring diagram with added description.
Posted By: howie ll
Date Posted: August 06, 2012 at 4:15 AM
How can you run the AC if the engine is off?
The compressor needs the engine running.
A latching relay buy the way is what the vehicle manufacturer would use.
-------------
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: oldspark
Date Posted: August 06, 2012 at 4:33 AM
Agreed about the ac not running with the engine off, but those I have seen (ie, usually Japanese) disable the ac clutch during cranking etc.
Hence many use the "usual" charge (light) circuit with added cutouts for idle and sometimes cranking.
The Japs I have seen use normal relays, though sometimes using the DPST with NO & NC contacts for cranking interlocks etc. I have yet to see latching relays used, but you know I avoid VAGs etc.
Posted By: howie ll
Date Posted: August 06, 2012 at 4:49 AM
He wants one touch, I was thinking of items which use one momentary button such as rear defog, that requires a latcher or at least a solid state latching circuit.
This all sounds like a bit of Heath Robinson, = a Kludge to me.
Why not just buy a retro kit, there are still manufacturers in the, US, South Africa and Israel.
Heck up to 7-8 years aqo when we were still installing them we used an English supplier.
In the US try ARA.
Note unless going into a Japanese Vehicle which has ready prepared wiring, compressor mount etc. this is a 3-4 day job for an EXPERT who is that rare beast, a good mech. and a good sparks.
Under engine block, drop either alternator or power steering compressor, mount AC bracket or change existing.
Fit new drive belt.
Drill 2-3" holes (2) in bulkhead, drop AC h/exchanger in front of rad, dashboard out, loads of wiring etc. etc. etc.
And don't forget back in the day we could pull an E36 dashboard in about 20 minutes, i.e. strip from floor to windscreen.
We stopped that part in about 98, after that everything in the UK got air ex factory.
-------------
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: oldspark
Date Posted: August 06, 2012 at 5:32 AM
I missed the single button....
In that case...
... where the circuit is powered by IGN +12V.
And the output controls the relay.
I suspect it powers up in the on state (+12V out), hence connect that to a relay connected to IGN +12V...
Or any flip-flip or divide-by-2 circuit (eg, the CD4017 can be div-2 to div-10 etc).
Or an on-off switch - push-button or rotary...
Posted By: mr_malina
Date Posted: August 06, 2012 at 7:58 AM
howie ll wrote:
How can you run the AC if the engine is off?
The compressor needs the engine running.
A latching relay buy the way is what the vehicle manufacturer would use.
I do not want to run it with the engine off, sorry if I gave that impression.
howie ll wrote:
He wants one touch, I was thinking of items which use one momentary button such as rear defog, that requires a latcher or at least a solid state latching circuit.
This all sounds like a bit of Heath Robinson, = a Kludge to me.
Why not just buy a retro kit, there are still manufacturers in the, US, South Africa and Israel.
Heck up to 7-8 years aqo when we were still installing them we used an English supplier.
In the US try ARA.
Note unless going into a Japanese Vehicle which has ready prepared wiring, compressor mount etc. this is a 3-4 day job for an EXPERT who is that rare beast, a good mech. and a good sparks.
Under engine block, drop either alternator or power steering compressor, mount AC bracket or change existing.
Fit new drive belt.
Drill 2-3" holes (2) in bulkhead, drop AC h/exchanger in front of rad, dashboard out, loads of wiring etc. etc. etc.
And don't forget back in the day we could pull an E36 dashboard in about 20 minutes, i.e. strip from floor to windscreen.
We stopped that part in about 98, after that everything in the UK got air ex factory.
I never thought about a rear defroster but that might serve the purpose. I already have the system installed, all I need to do is wire it and charge it. It was a PITA and do not plan to do this again.
Posted By: mr_malina
Date Posted: August 06, 2012 at 8:11 AM
oldspark wrote:
I missed the single button....
In that case...
... where the circuit is powered by IGN +12V.
And the output controls the relay.
I suspect it powers up in the on state (+12V out), hence connect that to a relay connected to IGN +12V...
Or any flip-flip or divide-by-2 circuit (eg, the CD4017 can be div-2 to div-10 etc).
Or an on-off switch - push-button or rotary...
I am trying to look up the symbols on this diagram, I do not really understand diagrams like that (wish I did).
Posted By: howie ll
Date Posted: August 06, 2012 at 8:27 AM
X 2 with that comment, I never got involved with the heavy stuff, I just did the wiring.
Push button switch to say timer relay, ignition controlled, timer relay shuts after about 10 minutes.
If its a latching relay you can use a momentary push-push operation.
-------------
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: mr_malina
Date Posted: August 06, 2012 at 9:49 AM
howie ll wrote:
X 2 with that comment, I never got involved with the heavy stuff, I just did the wiring.
Push button switch to say timer relay, ignition controlled, timer relay shuts after about 10 minutes.
If its a latching relay you can use a momentary push-push operation.
So I would have to turn the system back on every 10 min?
Posted By: howie ll
Date Posted: August 06, 2012 at 10:21 AM
That time was an example but you should never need more than 10-15 minutes, especially not with AC.
I had a couple of Maximas in the mid 90s where the defogger switched off ex factory after 10 minutes.
-------------
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: mr_malina
Date Posted: August 06, 2012 at 11:13 AM
howie ll wrote:
That time was an example but you should never need more than 10-15 minutes, especially not with AC.
I had a couple of Maximas in the mid 90s where the defogger switched off ex factory after 10 minutes.
Sometimes during the summer I would want on for long periods of time.
Posted By: howie ll
Date Posted: August 06, 2012 at 11:19 AM
I think we're at cross purposes, I'm talking about a an electrically heated rear and or front window, you're talking about AC. No timer needed for the AC of course.
-------------
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: oldspark
Date Posted: August 06, 2012 at 4:15 PM
Those symbols in my last diagrams are inverters hat exist as integrated circuits (ICs).
There are hex inverters - 14-pin ICs with 6 inverters & 2 pins for power (which are not shown on the diagram) - such as the CD4049, but there are others as well as many way of making inverters (using other logic chips such as NAND and NOR gates, or transistor, etc).
The other symbols are resistors & a capacitor.
Using electronics or chips (ICs) there are many ways to do what you want. But that will involve soldering etc which is not liked by many.
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