Alarm when handbag opens accidentally

[Navarro1]

Hi everyone, I'm new here and I apologise if this is a stupid question! I''ve taken on a project where I want to install an alarm system in my handbag for nights out because I am fed up of it opening and all my stuff falling out. I've found a simple circuit online but I was wondering could I add something in so I could set it to a vibrate setting instead of an audible alarm (for when I won't be able to hear an alarm) and then for daytime I could set it to an audible alarm? I don't really have a lot of electronics knowledge so have no idea how to add this in. Thanks for your help

eta I have posted a pic of the circuit but please let me know if for any reason it doesn't show

 

[KJ6EAD]

How would an audible alarm or even a vibratory one prevent unwanted handbag dumping?

 

[Navarro1]

How would an audible alarm or even a vibratory one prevent unwanted handbag dumping?

It's not to protect against theft as such, I just want it to go off if my bag opens so I'm alerted to it and can stop all my stuff falling out on to the floor which has happened a few times.

 

[KJ6EAD]

I never said anything about theft, nor did you in your original post so I'm having some difficulty with your use of language. It would help at this point to understand what kind of opening and closure device the bag has.

While it's certainly possible to install some kind of sensor or switch to activate an alarm, the practical solution is probably a different bag or an enhanced closure device on the existing one.

 

[Navarro1]

I never said anything about theft, nor did you in your original post so I'm having some difficulty with your use of language. It would help at this point to understand what kind of opening and closure device the bag has.

While it's certainly possible to install some kind of sensor or switch to activate an alarm, the practical solution is probably a different bag or an enhanced closure device on the existing one.

Oh sorry, must have misread! It just has a simple magnet to close it

I'm trying to tie it in with a college project too, but didn't know if it was possible before I chose it for a final idea! So was going to play about with the circuit and see if it worked first.

 

[KrisBlueNZ]

Can you replace the magnets with stronger ones? Small neodymium ones, maybe?

 

[Frenoy Osburn]

When you mentioned the magnet thing, I thought of a reed switch (a simple magnetic switch)

If you can place a small device next to the existing magnets, then this would be ideal.

The idea would be this: when the purse is closed, the magnets are close to the switch and it "turns the circuit off". When the purse is open, the magnets are further away from the switch and the switch "turns the circuit on".

Exact implementation will depend on how big of a device you need. I'll leave this here for a moment for others to contribute.

 

[Frenoy Osburn]

Can you replace the magnets with stronger ones? Small neodymium ones, maybe?

I think the existing ones should be good enough. The magnetic mechanism used to be present in laptops, clamshell mobile phones and I even found it on my old blackberry (the cover/holster had a small magnet that activated a switch on the BB when it was inserted). That was how the BB "knew" the phone was in the holster and then activated certain modes.

 

[Navarro1]

When you mentioned the magnet thing, I thought of a reed switch (a simple magnetic switch)

If you can place a small device next to the existing magnets, then this would be ideal.

The idea would be this: when the purse is closed, the magnets are close to the switch and it "turns the circuit off". When the purse is open, the magnets are further away from the switch and the switch "turns the circuit on".

Exact implementation will depend on how big of a device you need. I'll leave this here for a moment for others to contribute.

This makes sense, thanks Frenoy. Would I be able to set up some kind of circuit where I could select what mode I want it in? I.e vibrate/ sound or both

 

[Frenoy Osburn]

That's definitely a possibility, you can even go to an extreme by using your smartphone to control it. (That's really going to be overkill, unless you are thinking of commercializing it)

Using a MCU will definitely give you more headroom to add stuff later on. But I believe you could also use discrete components like those in the circuit.

Have you decided on some motors for the vibration? As well as pricing, battery type and form factor?

 

[chopnhack]

Perhaps a photosensor/transistor could be used as the switch between night/day mode to reduce complexity and eliminate the need for a μcu. It would not be as sensitive of course. I would suggest placing/stiching the vibrating device high up in the bag and perhaps include some loose metallic items in a small pouch next to the device such that when it goes off you will get both an auditory/tactile alert. The reasoning behind this is that you may not feel the vibration by itself if your purse is set down or even on your shoulder for that matter as the strap would absorb some shock.

 

[davenn]

I think the existing ones should be good enough

obviously not as they keep separating and the bag opens

I like Kris's idea it would be a way to solve the problem without any electronics

 

[Arouse1973]

I never said anything about theft, nor did you in your original post so I'm having some difficulty with your use of language. It would help at this point to understand what kind of opening and closure device the bag has.

While it's certainly possible to install some kind of sensor or switch to activate an alarm, the practical solution is probably a different bag or an enhanced closure device on the existing one.

Thats not what this Forum is about, it is about helping people with an interest in electronics. We can all say buy it from ebay. Who cares if a bigger bag with a better clip stops this, the OP might not want a new bag.
Adam

 

[davenn]

well the forum is about helping people and as Kris's totally practical method suggested
it doesn't need to be electronic
Sometimes there are easier and better ways to consider first

Yes it is an electronics forum but I think we should still be open enough to suggest all practical ways to help solve a person's problem query
Then with that info, let them decide which way they would like to go

when you think about it, the electronic methods suggested don't solve the problem, they only apply a "band-aid". Isn't it better to try and solve the initial problem ?

 

[Arouse1973]

The fact they supplied a circuit diagram indicates an interest in electronics, we should pursue this before say buy a new handbag. Thats all I am saying.

 

[chopnhack]

well the forum is about helping people and as Kris's totally practical method suggested
it doesn't need to be electronic
Sometimes there are easier and better ways to consider first

Yes it is an electronics forum but I think we should still be open enough to suggest all practical ways to help solve a person's problem query
Then with that info, let them decide which way they would like to go

when you think about it, the electronic methods suggested don't solve the problem, they only apply a "band-aid". Isn't it better to try and solve the initial problem ?

Good point, one must consider all solutions, but don't over look the fact that the OP also has other reasons for wanting to approach this: (college)

Oh sorry, must have misread! It just has a simple magnet to close it

I'm trying to tie it in with a college project too, but didn't know if it was possible before I chose it for a final idea! So was going to play about with the circuit and see if it worked first.

 

[(*steve*)]

Without reading everything in detail, if I wanted to trigger something on a handbag opening I would look a the sort of thing which is used on windows for alarms, namely reed switches and magnets.

You could make it much smaller by using a magnet and a hall effect sensor.

Another mechanical method is to use the tension of the handbag's strap to hold the bag closed. I'm sure you can see what I'm thinking

 

[Frenoy Osburn]

obviously not as they keep separating and the bag opens

I like Kris's idea it would be a way to solve the problem without any electronics

Well obviously I can't tell how effective the original magnets are, but based on the one's I've seen on purses, they are pretty strong to hold it together (at least when new). It's only when you apply excessive force: like twisting it about, dancing (maybe? ) that they tend to come apart.

Anyway, I could also very well be wrong.

 

[Navarro1]

Thats not what this Forum is about, it is about helping people with an interest in electronics. We can all say buy it from ebay. Who cares if a bigger bag with a better clip stops this, the OP might not want a new bag.
Adam

Thank you Adam!

 

[Navarro1]

Good point, one must consider all solutions, but don't over look the fact that the OP also has other reasons for wanting to approach this: (college)

Yes definitely, although I have been told this idea is too simple. I still want to play about with it though, I'm not able to use it for my final idea but thought it would help me learn a bit