Classic cars forum & vehicle restoration.

[rcx822]

I'll be adding an alarm as part of my rewiring and wondering which type of alarm sensor to use. I've had no luck with microwave sensors in the past, if I set the sensitivity higher I get false alarms, set it low and I need to wave my arms and punch the air to set it off. Never could find a decent balance point, even after upgrading to a decent branded sensor. I'm wondering if ultrasonic sensors are any better?

Might not bother with a sensor at all, I'm mostly just in it for the remote central locking and there's already an immobiliser in there. It's just that after my microwave sensor experiences I'm wondering if ultrasonic is any better at all.

[Old Wrench]

It all really depends on what and how you are aiming to protect.

Perimeter Detection (Micro-Switches) on doors, boot/tailgate, bonnet are the foundation of any decent alarm system.

Spacial Protection, can use Ultra Sound (Ultrasonic), Microwave and/or PIR (Passive Infrared): the first two rely on the Doppler Effect. A wave propagated, returns at a different speed.

PIR detects a change in ambient temperature, emanating from the intruder.

http://en.wikipedia.org/wiki/Security_alarm#Ultrasonic_detectors

In order to achieve the highest possible level of true event threat detection and a simultaneous high level of false trigger event rejection, means significant cost.

The lower end microwave and ultrasonic detectors suffer from cheaper components and poor design, which is why they also suffer from high levels of false trigger.

If you are really concerned at the risk of loosing your prized asset, then fit a tracker: indeed, insurance underwriters now invariably insist a tracker is covertly installed for risk values (and car types) above certain low value thresholds.

http://www.tracker.co.uk/for-your-vehicle/car-tracking/

http://www.cobravehiclesecurity.co.uk/stolen-vehicle-tracking.aspx
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Well, apart from that, did you enjoy the play, Mrs Lincoln?

[peter scott]

Trackers are really quite cheap now and are very versatile. You can configure them to send you a text message when your vehicle shifts its position more than X feet and to continue texting its current position. You can also send it a text to control some aspect of your vehicle. e.g. lock the doors, immobilise it or perhaps sound a siren.

They work on GPS and so if your vehicle is now located in the robbers' premises you can know where it is within a reasonable radius but asking it to sound a siren when you get there might help to pin-point the exact location.

There is no need for periodic costs other than a pay as you go SIM card and this costs virtually nothing with GiffGaff.

Peter

http://www.ebay.co.uk/sch/i.html?_odkw=&_osacat=139838&_from=R40&_trksid=p2045573.m570.l1313.TR6.TRC2.A0.H0.Xtk103&_nkw=tk103&_sacat=139838
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Riley Blue]

When I went shopping in Sainsburys a few days ago I was given a voucher for a free PAYG sim and £10 top up - it's going to be used for precisely this purpose.
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David

1963 Riley 1.5
1965 Riley 1.5

[rcx822]

[rcx822]

I've fitted the alarm and it just relies on the door switches. My objective was to get remote central locking and that's built into the alarm module, so objective met. Until I find a decent sensor that is both sensitive enough and doesn't give false positives I will go without.

I've done some reading on trackers. The commercial trackers also rely on GPS to get location and GPRS to report back to base. So in theory there's no advantage over a self installed SIM card tracker. And £200 gets you a detector or blocker to both locate the tracker and disable it, so it's not as secure as you may think. Still, a thief might think twice if there's a tracker even if he knows about it. Maybe the solution then is to place the tracker in a location that they won't be able to access it, even once it's been located. They've found the tracker but can't get at it... tricky but that might be the answer to GPS detectors.

I've used two trackers, both low cost, self install, and very popular on ebay. One was the Xexun TK103 designed for cars and the other the TK102 which is a personal/universal tracker. The one designed for cars has an external GPS antenna and GPRS antenna, and can be triggered by the alarm. But this relies on a decent alarm. The other features like engine immobilisation, ability to listen and take photos are just not worth it. So this time I'm sticking with the smaller and simpler TK102 which is tiny and only requires a power feed. It in turn doesn't have an alarm trigger, but can be set up to notify you if the location changes.

These home install trackers really need to be used with decent software, communicating by SMS is tedious. The best I've found so far is gps-trace.com, which can be set to alert you if the tracker starts moving. Not as good as an alarm alert because by that point the vehicle has been compromised and is on the move, plus you will get an alert each and every time the vehicle is legitimately moved. But will see how I get on with that.

PS for anyone considering a self install ebay tracker, just make sure it's an original Xexun. Half the trackers on eBay are Xexun fakes and are not as solid. And make sure it's the model that has an internal battery. Useless without that... all the TK102 have a battery, but only the later TK103 have one.

PPS the short battery life I reported on my tracker earlier in this post appears to be a faulty battery. It has given up totally now after years of use. New battery on it's way...

[Old Wrench]

[rcx822]

I wondered what had happened to you Old Wrench.

It's a relief to hear that explanation of how perimeter switches are effective, I really had enough of trying internal sensors.

With the microswitches, fancy saving me doing the online searches and linking to one you've used?

My approach for now will be to experiment a bit more with the little Xexun, to see how reliable and consistent it is when used with an online service like GPS-Trace.com and later I may upgrade to a tracker with SMS notification of an alarm trigger. I do also think there's some scope in making the tracker difficult to access.

[Old Wrench]

Wide choice.

Start with say Rapid Online and something like this:

http://www.rapidonline.com/electronic-components/cherry-gptcnd01-microswitch-spdt-15a-250v-ac-light-force-overtravel-button-screw-50-2688

Also search Farnell, Maplin and all the usual suspects!
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Well, apart from that, did you enjoy the play, Mrs Lincoln?

[baconsdozen]

We owned a shop in Lowestoft,we spent money on all sorts of alarms and security devices yet had stock stolen and cars/vans broken into.
We then used this

never had another problem.
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Thirty years selling imperial hand tools for old machinery(Now happily retired).

[rcx822]

Wow he looks sweet!