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Connect output for small (piezoelectric?) speaker to headphone jack

nathan

Feb 21, 2010
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Feb 21, 2010
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Hey all,

I have this little toy "radio" that plays one of many annoying sounds when you press a button. It's hooked up to one of the small disc-shaped speakers that you used to see in PCs. I tried cutting the wires and splicing them into a headphone cord, but no go. Is there any way I can make this happen, or are the signals just completely incompatible?

My end goal is to make the output louder and more annoying, and unfortunately since the speaker wires come directly off a PCB then I see no easy way to just juice it up without risking the electronics (of course, I obviously have no idea what I'm doing when it comes to electronics, so if there's something else I can do there too then let me know).

Thanks!
Nathan
 

Resqueline

Jul 31, 2009
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Piezoelectric speakers are in principle capacitors, and they need a fairly high voltage but very little current to operate. Ordinary headphones/ speakers are in principle coils, and need a low voltage and a fairly high current to operate.
You may get hold of additional discs and connect them in parallell and see if the circuit is up to driving them all, or you could make an amplifier. The discs can take up to around 20-25Vpp w/o cracking up. What kind of battery is in there, and what are your constraints?
 

nathan

Feb 21, 2010
3
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Feb 21, 2010
Messages
3
Hi Resqueline,

I have a four AA 1.5v cells driving it at the moment. I would like to get it down to just using two cells, but I figured I'd get it working first and mess with the power afterward.

Ideally what I'd like to do is wire it to a miniplug jack so I can just plug any old computer speaker in there and have it play sound. I don't really have any space constraints to speak of. The only other things I'm constrained by are the limitations of the PCB that I have to work with and my complete and utter inexperience when it comes to projects like this :)

Thanks for the reply!
Nathan
 

Resqueline

Jul 31, 2009
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Ok, I see. You know there are some computer speakers that have a built-in amplifier.
Otherwise it could possibly be done as simple as using two NPN and two PNP transistors to make a full bridge emitter follower buffer amplifier to get the current level up to speaker levels. Try Googling with those keywords to get some ideas about what I mean.
 

nathan

Feb 21, 2010
3
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Feb 21, 2010
Messages
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Thanks for the advice!

I'll do some more research and see what I can piece together.

Nathan
 
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