Hi, this is Wayne again with a topic “Weekend Project: Shrieking Anti-Theft Backpack”.
Ever had your bag stolen, it really sucks in this weekend project by steve, hobley, we’ll show you how to put a hidden car style alarm in your backpack to thwart would be there aren’t a ton of parts you need to make this build. The circuit is really simple, just be sure to have some scrap wood on hand to make the enclosure using just the red and black wires attached to the siren and the battery clip we’re going to put all the components in series. The idea is that the alarm will sound only when both audio plugs are removed from the jacks one jack inside the bag for arming or disabling the alarm and the other outside the bag to act as a trigger mechanism. The sockets have a normally closed switch built right in which will act as the alarm trigger we’ll be connecting through only two of the three terminals shown here solder.
All the components together protecting all exposed connections with shrink tubing next, we’ll be using the audio cable to make two trigger cables. One long and one short cut the cable at about six inches from one of the plugins set. The shorter cable aside make a loop on the cut end of the long, cable and secure it in place using a few inches of solid core wire with the insulation removed and then further secure it with heat shrink tubing, take a moment to test the build before Installing it in the bag plug in at least one of the audio cables into the jacks before connecting the battery, the alarm should sound when you remove the audio plug, but you might want to put on some hearing protection. The alarm is very loud. You can also test it by disconnecting the battery and using a continuity tester. If you want to spare your ears the components in this build don’t easily fit into any of the common size, electronics enclosures we found so we’ll be making our own out of scrap wood. You can use wood glue to join all the pieces together, but if you’re in a hurry, hot glue will work just fine if you’re feeling fancy give it a good coat of paint.
You also may need some velcro tape to secure the battery holder in place. If it’s wobbling around drill holes in a small piece of acrylic to form the speaker grille, but don’t secure it yet wait until we place the enclosure in our bag. Speaking of the bag, fit the enclosure into a space in the bag. In a bottom corner, cut a large hole in the side for the speaker and a tiny hole for the audio jack secure.
The enclosure in place with the acrylic speaker grille and use a pair of thin washers to hold the audio jack in place to use the bag, connect the short wire and leave it in the bag. As you go about your daily business, when you want to arm the alarm, such as when you’re working out in a public place, plug in the longer cable into the jack on the outside of the bag and secure the loop to a chair or table leg. And then disconnect the internal plug. If someone grabs your bag and runs off with it, the external cable will be unplugged, the circle will close and the alarm will sound.
If someone grabs your bag and runs off with it, the external cable will be unplugged. The circuit will close and the alarm will sound while it won’t actually prevent theft. This project certainly discourages it in the moment.
If you have any doubts about that, i recommend that you try actually walking around with one of these alarms in your bag. It definitely draws attention sure the thief could put their headphone plug inside the jack and disable the alarm, but they’d really have to know about it. Ahead of time, when we were buying the parts online for this project, we actually noticed that finding the audio jacks with a normally closed switch feature is kind of difficult. If you have any suggestions for other plugs that have this sort of feature, especially ones, that can’t be defeated by a common set of headphones, be sure to let us know in the comments. Let’S take some time to go over the comments from our last weekend project. The bionic claws regarding the expensive servo that actuates the claws scott perry asked us if a solenoid would work just as well. I think that that’s a great idea it might. My initial thought would be that you might need a bigger battery. It would consume more current.
You might need a higher voltage battery as well. I would be reluctant to say yes without some testing. Some people also recommended flipping the servo on its side so that the servo arm doesn’t stick up out of the enclosure. That’S a great idea. We just need to redesign the 3d model a little bit and it’d be perfect. Alright, that’s it for this time, we’ll see you in the next weekend project.
If you liked this video subscribe to our website or send us a comment on facebook or twitter be sure to check out our other project videos or visit us on makezine.com .