School project help

[CrazyPuzzler]

Well, fellow tempers, I really need your skills and knowledge this time. I need you to help me with a school project -yeah you read it right!-, which I will get a grade for that counts as a quarter of my exam!

So here's the deal: we have a subject in school that's called 'technical design' and you need to work in groups and invent things that will solve problems people have in common at-home situations. Nothing special about that part, but the group I have to work with has put me up against my greatest challenge so far; they want me to create some kind of key ring/sticker that makes a beeping sound when you press a button on a remote. The idea is that you attach the sound emitting device to something you often lose (like car keys), and you find them again by simply following your ears. that's basically a good idea, but since I'm not good at this stuff I don't know where to start. Therefore any help would be greatly appreciated!

these are the things I've gathered so far:
- 2 sets of walkie- talkies
- a dozen of those mp3-player mini-speakers one puts in his ears
- tools like screwdrivers

things I'm willing to get:
- almost everything I need that's under €10

my first question is if anyone knows if I am even able to to this? If so, how do I have to do it? (preferably something with the walkie talkies) And if not, what else do you suggest?
Post all your useful tips or advices!

P.S. sorry for bad English

 

[injected11]

That device already exists, though I have no idea what it's called. My sister has one on her key ring.

I'm not sure what you're trying to do with the walkie talkies or the mini-speakers. They both seem like they'd be adding clutter to something that should just be 'emitting sound from a device, hearing it with the bare ear'.

 

[FAST6191]

An interesting class.

A thought- most of those toy walkie talkies have a morse code button on them. Simply hold it down and it makes a tone (replace the switch with a transistor and hook the transistor gate up so as to trigger it when it receives an input).

Failing that rig up a tone generator (you could probably build something with a 555 timer if you had to) to the microphone points as that will work just as well. It does really need to be a tone generator or something that varies a bit- constant voltage will do little.

Your main problem then is powering the walkie talkies (or their internals) not to mention fitting them in a device- I assume they have not changed much in years but they did not half rinse batteries even on standby when I was playing with them and they are not that small inside either.

Sticking with radio a better option might be something like a miniature remote control car- hook the motor lines to a speaker. I am sure we all saw http://ucables.com/img/mini-remote-control-car.jpg the other year.

 

[CrazyPuzzler]

An interesting class.

A thought- most of those toy walkie talkies have a morse code button on them. Simply hold it down and it makes a tone (replace the switch with a transistor and hook the transistor gate up so as to trigger it when it receives an input).

Failing that rig up a tone generator (you could probably build something with a 555 timer if you had to) to the microphone points as that will work just as well. It does really need to be a tone generator or something that varies a bit- constant voltage will do little.

Your main problem then is powering the walkie talkies (or their internals) not to mention fitting them in a device- I assume they have not changed much in years but they did not half rinse batteries even on standby when I was playing with them and they are not that small inside either.

Sticking with radio a better option might be something like a miniature remote control car- hook the motor lines to a speaker. I am sure we all saw http://ucables.com/img/mini-remote-control-car.jpg the other year.

I found a car just like the one you mentioned in your post in my attic

, but there's a problem with it:
when I try to 'drive' it, it does nothing, also the little light on the charger that indicates when the car is charging doesn't light up when I put the car in it. And the strangest thing is that when I put the car in the charger and hit the gas at the same time, it actually DOES drive, and the charging light DOES light up!
but the car isn't really charging, because when I put it off the charger again I get no response from it

So the question is 'how do I solve this problem?

' (I already changed the batteries, so that's not an option)

 

[FAST6191]

When you say changed batteries do you mean in the handset or the little car itself? It could be a fault with the charging circuitry but what you just described sounds like classic rechargeable battery in deep discharge (a small thing like that will do it quite happily if you have not used it for a year or more) but still able to get power when connected.

Assuming there is nothing special about the charging circuitry (some rig a charge counter to an EEPROM......) you could consider sticking in a big capacitor instead and justifying it (for prototype purposes) if called on it.