Alarm question

If the resistors are in the old detector, they need to be in the new one, some you need to know before ordering the correct part, e.g. "Honeywell = Green resistors" as you can't change them, they're potted in.

But the same value resistors for tamper/fault/end-of-line will be needed as the existing ones.

should be ok.

iders although now it appears to always be the same detector triggering the alarm. I thought it would be wise to switch it for a dual detector type to remove the spider issue and assuming it has some sort of fault.

in place. Would these have to change if I change the type of detector?

I replaced all of ours for dual-tech years ago. Not because we were having any particular problems, I just liked the idea of having 2 sensors to trig ger an alarm, reducing the chances of false triggering.

If its spiders inside the sensor rather than across the face then make sure the cable entry point is sealed. I used a bit of blu-tack.

My system doesnt use resistors but my understanding (as already mentioned) is that you will need to use the same values that are used in the current s ensors.

Alan

Thanks both. So the resistors are in the sensors themselves as opposed to the alarm box?

The Texecom Elite AMDT PIR that I bought does have several resistor options. These are described in the installation manual which you can download.

Your control panel may let you choose (set) a resistor option. The settings in the PIR and the panel need to match! One option might be not to use resistors but I think that you would loose some of the tamper detection. I added resistors to two of my old PIRs when I changed to a new control panel. The others I replaced with the above unit.

Yes. AIUI the resistors set a third state (open circuit and closed circuit being the other two) so the alarm can tell if Burglar Bill cuts a cable or shorts out a detector.

Yes, they may be. But, to my surprise my new alarm box did come with two sets of different value resistors which could be used on PIRs that did not have them, and door sensors. I had already bought some on ebay!

What do these resistors do. I can well recall a bridge circuit being used to guard against both cable cutting and shorting. It relied on resistors. Two things went wrong with this ploy. NOisy resistors when they age, and condensation on the resistor making it vary. Brian

Basically that. You get one resistance when the circuit is normal, another when the sensor is triggered, possibly a different one again if the sensor indicates a fault (such as a PIR with anti-mask) and obviously open circuit if someone cuts the wiring and short circuit if someone tries to bypass the wiring.

The resistors supplied with my alarm panel have been OK so far 1% tolerance ones I think.

The reed switch contacts on doors have the resistors potted in, so shouldn't be an issue.

Thanks all for your help so far. I have now looked at the alarm literature the fitter left. I looks like the original spec was dual all around but see ms we changed most to single - I assume because they were smaller (now payi ng for it). The model number of the dual one is Honeywell DT7550 (don't ha ve model number for the single one). On the spec he left for the circuit in question (currently a single detector) is has written 5.1 ohms (I assume h e means 5.1kohms). Oddly each one seems to be different.

The dual model seems to have been replaced by a DT8016 but the resistor opt ions that come with is are 1k, 2.2k, 4.7k, 5.6k. Should I be looking for a different model which has a 5.1k one or is the nearest one (4.7k) be ok?

Thanks all Lee

What model is the alarm panel?

Thanks

It is a Honeywell Galaxy 2 series (I believe a 2-20). I have now taken the sensor off thankfully without setting the alarm off ?. There are 2 resistors in it. 1 for alarm and 1 for tamper. The markings are brown, b lack, black, brown,brown. Looking online, depending on which whether you re ad this forward or backwards you seem to get 1k or 110. Any ideas?

Sounds correct, Honeywell panels use 1k+1k (sometimes known as "green") resistors, so what was with the 5.1k resistors on the old sensor?

The 5.1 was written in the paperwork by the fitter. I wonder if this is the resistance of the circuit itself?

Probably a 1K +/-1% tolerance resistor. The 'leftmost' digit corresponds to the colour band at the very end of the resistor body. If there's any doubt, the easiest way to resolve this is to test with a cheap multimeter (it's either going to show a 1K or a "110" ohm reading). There's an order of magnitude difference between the two possibilities which the cheapest of cheap multimeters will readily identify which "Ball Park" you happen to be in. :-)

Thanks all for your help so far. The resistors were indeed 1k. I have now f itted the new sensor (Dt8016f5) but when I try to get out of engineer mode it detects a tamper on the new sensor. Any idea how I clear this? I have us ed the same resistors from the old sensor so should be the same?

Thanks.

Lee.

Worth a stab at ASCII art to show how it's wired, or a paint image uploaded somewhere?

The wiring is to a terminal block labelled as follows

T T C NC -v +v

And I have wired as follows

T - yellow T. - R1 c. - R1 and R2 NC. -R2 and Blue -V - black +v - red

The alarm itself seems to work correctly in the sense that the led lights correctly as it detects movement.

I couldn't see how the fitting detects the front being removed etc for the tamper.

Thanks

Lee.