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Pgordon
Member
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Posted: Monday Sep 17th, 2007 03:34 pm |
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Now that all the flash parts are available for Comfort G2, it’s likely that I’ll be doing some major work on the panel again soon. As ever, the biggest PITA with this is that as soon as I power-down the system, my main siren goes off. Clearly I therefore need to provide a 12V hold-off to the siren to shut it up whilst I’m working on the panel. Normally, I frig some Heath-Robinson-esque arrangement that involves disconnecting the siren cable from the SIREN terminals on the mainboard, and twisting the bare wire-ends round a temporary supply (usually a wall-wart, since I don’t usually have enough slack cable to pull them down to reach the battery)...
Frankly, this is pants.... it takes a couple of minutes to complete the above bodge, during which the siren is blaring, and it almost always “falls off” during the work in progress, setting it off again... (and It takes a minute or two to reverse the bodge at the end as well).... Net result, - my neighbours aren’t very happy with me!
Therefore, before I embark on the next round of work on the panel, I want to sort out an easy, reliable, and straightforward way of managing the siren hold-off. I’m envisaging something that just involves flicking a switch mounted somewhere inside the main enclosure.
When work commences, the requirements always include:
- cutting the mains power
- disconnecting the battery from the mainboard
- connecting a hold-off supply to the siren
Clearly, it would be a simple matter to break the cable from the battery, & insert a switch to cut the input to the mainboard. I also want it to switch the battery terminals over to supplying the hold-off to the siren... – Presumably, I shouldn’t connect the battery to the siren cables whilst they’re still connected to the SIREN terminals on the mainboard, - as otherwise I’ll be pumping 12V INTO the mainboard on those siren terminals... – not sure what the effect of that might be....
So I’m after suggestions how to achieve this easily... – I’d need to supply both + and – to the siren, so I guess I’d need to switch *both* battery terminals, even though I’d only need to cut one of them to remove battery power from the mainboard.... so I guess at least I need a DPDT switch on the battery output leads to switch them both from the mainboard to the siren... – what about the issue of the 12V then being connected to the SIREN outputs? – could I just put a diode in the + lead between the switch & the SIREN connection?
The layout I'm contemplating is shown in the attached JPG. The 12V FROM the battery is connected to the centre poles in this diagram, - the BAT & SIREN points are the terminals on the mainboard where the battery & siren are connected to Comfort. When switch is in position 1 (leftmost), the + and – terminals from the battery are connected to the usual battery in terminals on the mainboard, as per normal. When switched to position 2 (rightmost), the battery is disconnected from the battery in terminals on the mainboard (thus achieving 1 of the 3 requirements), the 12V battery supply is instead rerouted to the cable going off to the siren, thus providing the hold-off required to keep it silent. The diode is inserted in the cable before it enters the SIREN terminal such that current is able to flow OUT of the terminal, but not IN to it.....
Does this make sense? – would this be feasible? – any thoughts? – alternative suggestions?
TIA
Paul G.
Attachment: Comfort siren hold-off.jpg (Downloaded 55 times) Last edited on Monday Sep 17th, 2007 03:40 pm by Pgordon
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Pgordon
Member
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Posted: Monday Sep 17th, 2007 04:30 pm |
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| Also had another idea, just using a 3PDT switch, conected as per the amended JPG below... Attachment: Comfort siren hold-off 3PDT.jpg (Downloaded 55 times)
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slychiu
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Posted: Tuesday Sep 18th, 2007 02:14 am |
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Both these schemes should work
It wont comply to the new EN50131 which you Europeans have introduced though - the burglar would be able to do the same thing
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Pgordon
Member
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Posted: Tuesday Sep 18th, 2007 09:43 am |
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Thanks Chiu.
The toggle switch will be inside the main panel enclosure though, so methinks that by the time a burglar has access to the siren hold-off switch, I would already have a few more pressing things to worry about!
Can I take it that, with the 3PDT switch method, it is OK to just break the SIREN+ line (or whatever it's called) to the siren when the switch is thrown, and not bother to also break the other line... - It wouldn't be hard to break both lines to the siren terminals, but obviously I'd then have to use a 4PDT switch instead...
Paul G.
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ident
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Posted: Tuesday Sep 18th, 2007 10:34 am |
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There should be no problems with breaking the SRN+ to the siren only
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Pgordon
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Posted: Tuesday Sep 18th, 2007 10:42 am |
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ident wrote: There should be no problems with breaking the SRN+ to the siren only
Cool. Thanks. 3PDT switch now ordered. I'll mount it on a piece of stripboard with some terminal blocks just like the ones on the main board, and mount it on some pillars inside the enclosure on one of the available mounting positions.
I'll let you know how it works.
Paul G.
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Pgordon
Member
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Posted: Thursday Dec 27th, 2007 02:47 pm |
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Got the bits in front of me, - just wondering before I start assembly, is there any particular gauge wire I should use? - I ask because the battery connection cable from the spades on the battery to the BATT connector on the mainboard (JP52 is it?) are a fair bit chunkier than any of the other 12V cables in the case....
I think given the length of this existing battery cable, and the spaces available in the case where I can mount this board, I *may* need to extend them slightly... in so doing should I be concerned about what gauge wire I use?
Cheers.
Paul G.
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ident
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Posted: Friday Dec 28th, 2007 01:10 am |
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The siren may take about 1 Amp, hence the cable needs to be able to take that current without melting. The gauge of the battery cable is more than enough for several times that current.
However the function of the siren hold off is to charge the internal siren battery not to drive the siren, so the wire gauge should not be an issue. The siren sounds only when you remove the voltage.
Make sure the wire does not become warm in normal operation
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Pgordon
Member
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Posted: Friday Dec 28th, 2007 06:52 pm |
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Well, Ive constructed the board, will get round to fitting it tomorrow hopefully... I've made it as small as I possibly could, and I've mounted it "double-decker" style using tall pillars over the top of an ADM01.
I've attached a small photo of it in case anyone's remotely interested!
Cheers.
Paul G.
Attachment: IMG_1315.jpg (Downloaded 32 times)
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Pgordon
Member
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Posted: Sunday Dec 30th, 2007 03:32 pm |
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OK, first problem! - after installing & testing the switch, it didn't work... - everything is 100% hunky-dory with the switch in normal mode, but when in "hold" position, with the panel powered down, the siren still went off... - couldn't immediately see why, - I measured the voltage across the SRN+ and SRN- terminals in this state, and I was getting the 12V from the battery, via my switch (actually, I'm measuring 13.8VDC from the battery...) so what gives?
Well, I returned everything to the normal state, measured across the SRN terminals again, and I see that the Comfort Mobo is only providing 3.8V to the siren....
So my question is; Is the voltage difference what is causing this not to work? - I guess I could test this by rigging up a variable PSU set to as close to 3.8 as I can get (I think 3.5 is available) - will this be close enough?
One thing that kinda makes me think the voltage difference is at least having some effect is that I got 2 entirely different siren sounds between when I was giving it 13.8V and when I was giving it nothing at all... My next thought is to use a little DC-DC converter allied to my switch. - I have one lying around here, but it only offers 3.0V and 4.5V output settings, which are fairly close, but not exact...
Any thoughts / advice anyone?
Cheers.
Paul G.
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Pgordon
Member
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Posted: Sunday Dec 30th, 2007 03:55 pm |
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Right I tried with a wall-wart, but the the closest settings I could get were 3.0V or 4.5V. I tried both, and neither worked, - producing the same result; i.e. when either of those voltages were applied to the siren, the sound pattern changed but didn't stop... I'm guessing here that its sensing the different voltage as a tamper condition?
do (can?) DEOL settings apply to the siren? - I know I have DEOL's fitted and set on all my zone sensors, but I don't know if it's even an option for the siren...
Or, could it be the tamper circuit? - I didn't fit the siren myself, so I don't know for certain how it's wired... might I also need to ensure that I maintain a voltage at the TAMP terminals as well?
Paul G.
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Pgordon
Member
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Posted: Sunday Dec 30th, 2007 07:18 pm |
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Hmm.. double-checked the installation manual, and it definately states the SRN terminals at JP9 are 12V... - howcome I only measured 3.8 during normal operation?
Confused....
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admin
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Posted: Monday Dec 31st, 2007 02:20 am |
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I cannot see where you get the 3.5V from
The voltage across the SRN+ and SRN- terminals should be about 12V when the siren is not sounding (normal for Siren Reverse)
Note that SRN+ is connected to the 12V supply and SRN- goes to about 1V in normal mode
Do you switch off power to Comfort in the Hold mode? This may cause problems if the battery voltage is going back to the siren terminals through your switch. Does it work when power is on?
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Pgordon
Member
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Posted: Monday Dec 31st, 2007 12:00 pm |
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Yes, I have all power to the mainboard cut when I switch to the hold position, - that's pretty much the point of the excercise, - so I can work on it (swap firmware chip etc.)
I just double-checked the readings, with the switch in normal mode - i.e. not actually doing anything - the battery terminals are connected to the BATT connection on the mainboard, and the siren is connected to the SRN connections - these *just happen* to be going through my switch...
I get 13.8V measured directly across the bettery terminals, and exactly the same at the BATT terminals on the mobo.
I get 3.87V directly across the SRN+ / SRN- (JP9) points on the mobo, and exactly the same at the JP9 and SRN blocks on my switch.
The battery is connected and charging, the system is working absolutely 100% perfectly, - no sirens are going off!
When I want to work on the panel, I FIRST cust the mains power. Clearly this has no effect on the system as it carries on working off the battery... Then I flick my switch over to the hold position, this has the desired effect of powering down the system as the battery is disconnected from the BATT terminals.. in this state, I measured:
11V at the SRN+ / SRN- points on the mobo, and on my JP9 & SRN blocks on my switch... = clearly I'm putting the battery voltage back IN at the mobo SRN terminals... - this isn't what Id expected, and I guess could be the cause of the problem? curiously I also measured a small voltage (about 0.7V) at the BATT terminals, so it is possible that the voltage at the SRN port is somehow bleeding back through the main circuitry?
I'll remove the switch & double-check how its wired, - I don't think I deviated from the design described in the JPG, and I did fairly thorough continuity testing of the switch connections once I'd made up the board... perhaps I'll swap it for 4PDT as I mentioned previously, so that I can break the SRN- line as well, which should be absolutely guaranteed to ensure there is nothing being left connected to the SRN terminals on the mobo when I flick the switch..
That being the case, can you confirm that this scheme *should* work to keep the siren silent? - i.e. will the loss of other signals from the mobo (e.g. TAMP) also cause it to sound?
Cheers
Paul G.
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admin
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Posted: Tuesday Jan 1st, 2008 02:40 am |
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Suppyling 12V to the siren through the switch should be sufficient to prevent the siren from sounding. The circuit should work as far as I can see. Try the 4Pole switch as you suggest
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