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Forum Index : Electronics : Tamper/trembler switch
| Author | Message | ||||
CaptainBoing Guru  Joined: 07/09/2016 Location: United KingdomPosts: 1985 |
Hell forum. A while back there was a discussion about various methods for detecting tampering/panel opening etc and the best way to proceed. I found some likely threads but they don't bring up the discussion - maybe too old or something: Tamper/movement Alarm ideas? Ball-switch vs Accelerometer.... ... any hoo, here's a new thread. I have just got a pack of ten of these little switches which might help.. They are formed of two leads leading to a vacuum(?) filled can. One of the leads then forms a very delicate, "wobbly" spring around the other. It seems any significant movement from any direction triggers it sufficiently - bouncy as hell but who cares, you want the signal right? https://www.ebay.co.uk/itm/10pcs-sw-18020p-electronic-shaking-switch-vibration-sensor-RDD-FH/153302967713?ssPageName=STR K%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649 a fag-packet drawing of the innards looks something like this:  maybe something else to explore? regards |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1122 |
I know this is a very old thread, but rather than create a new one; I need some sensitive vibration \trembler switches as part of my alarm system. Have received a couple of samples from AliExpress, similar design concept as above, but none of them work unless you hit the sensors with a hammer to the point of breaking them. Pulled one apart and the tiny brass spring is way too stiff and cannot possibly vibrate as it doesnt have enough mass at the end. Has anyone recently purchased something like these that are sensitive and actually work??. Cheers Mike |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 378 |
Hi Mike, what about just using a magnetic reed switch. Or even a mercury switch. I don't know exactly how you want the switches to operate but these have been around forever and still function fine. Pete |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1122 |
I want to mount the trembler switch on the inside of the main door on a 12m steel shipping container, mounted on timber posts; so that when the thieving scumbags come back and attempt a break in by bashing the outside security padlocks, the strong ringing vibrations will trigger a warning alarm prior to turning on the battery operated electric fence unit connected to the container body. I may use one of those flat piezo disks glued to the door + DC voltage comparator circuit; will have to do some tests to see what voltages are generated by the piezo. Seems a trembler switch may be a simpler solution.... Mike |
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Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 427 |
I remember a smart guy back in the 1980's who used a gramaphone stylus/needle that obvoiusly changed a mechanicle movement into an electrical impulse. He put some circuits on it so the sensitivity could be adjusted. The only drawback was that excessive bashing/vibration could damage the stylus/needle mechanicle bit. So some sort of arrangement was made to stop this. I used it with great sucess as an early alarm sytem on a motorbike. Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
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Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 580 |
Godoh,s reed switch idea has some merit, mercury switches need to be tilted a fair bit to close the contact. If the reed switch can be mounted (disguised) behind the padlock and a small magnet is glued to the padlock then it could be made to trigger your alarm as soon as the padlock is moved away from the reed switch. Reed switches, being usually in a glass enclosure are fragile so you'd need to arrange it for the reed switch being closed for no alarm. So when the switch is hit the alarm goes off too. |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1122 |
Reed switches do have merit, we use them on timber doors and driveway gates, mounting them behind a padlock would be somewhat obvious and hiding them behind the steel door wont work though the metal. May bolt a small Fake access door to the side of the container, nothing behind it except the steel wall, with a single cheap padlock. It would be an obvious to them easy entry point, once the door opens it activates the "protective devices" Mike |
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wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 990 |
I was approached by a customer to make a gas guns to scare birds, it had electronic timing a real time clock and could be programmed to meet local council bylaws. It also had a remote trigger input. A farmer bought one from our customer as his shed had been emptied out of a heap of tools one night. So the farmer set the gas gun with a switch at the door that if the door opened, it triggered a blast sequence. There is a solenoid click a quiet whooshing sound and then a shotgun sized blast that would easily waken the dead and scare them back to death. Sure enough a few weeks later the farmer was woken by an almighty blast followed by a car leaving his property going like a bat out of hell, the intruder never returned. I'm guessing he didn't know what it was but assumed the farmer had a 12 gauge shotgun and had missed him. True story ! I still have enough parts Mike do you want one for the container if they get the door open ? (dont forget to install a bypass switch......) Edited 2022-07-11 23:37 by wiseguy If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 1985 |
in the states you can buy shotgun cartridge holders that you nail to a fence post and then use some mechanism (trip wire etc) to deter intruders. |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 5882 |
https://core-electronics.com.au/fast-vibration-sensor-switch-easy-to-trigger.html It's available from adafruit. A solid-state accelerometer should also do the job. Jim Edited 2022-07-12 08:06 by TassyJim VK7JH MMedit MMBasic Help |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 378 |
Hi Mike, sounds like you have thief problems , seems to be a rise in people who think it is fine to take whatever they believe they need from others. Having an electric fence unit hooked up to the container may be a legal problem though. Setting man traps is pretty dodgy legally, it may be worth looking into. One way that would not hurt them but may deter them is to have some way of releasing a bad smell or spraying them or the area they are in with something that smells really bad. Methyl Mercaptan or Sulpur dioxide come to mind. If a spray of either of these were to be directed towards their clothes or lower body then the smell may deter them. Maybe a warning sound such as a recorded message with a Dalek voice would help, warning them that to continue will bring on unintended consequences. Anyway good luck with the project,I hope that they never return. Where I live we have had peoples containers broken into as well. They put containers on their land prior to building to hold their tools etc. Seems that the temptation is too much for some folk. Cheers Pete |
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