Quick Picaxe Prototyping – Part 3 – Speaker

The completed speaker board

The completed speaker board

The third installment of my gripping series of picaxe parts is a speaker, to make use of the sound command on the picaxe.I found the tiny speaker in one of my many boxes of junk, it is from an old 3310 i used to use.

Picaxe Speaker Schematics

Picaxe Speaker Schematics

Again the scematic is very simple, with just 4 parts in total on the assembled board, the Speaker, the 10uF capacitor, the terminal block, and the board itself

The completed speaker board, from the back

The completed speaker board, from the back

The shot from the back isn’t that pretty, you can see the double sided sticky tape I used to hold the speaker on. i was contemplating using my hot glue gun, but it was outside in the shed, and it was late when i made this.

Anyway, i hope someone can find a use for these things,
Have fun,
Matt.

Edit: After playing around with the speaker a bit, it seems to have a very limited frequency response, with a massive peak in it, i figure because it came out of a phone, and was optimised for voice. So I’m going to dig into my boxes of junk, and try to dig up another small speaker to update the the unit with a better one.

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4 thoughts on “Quick Picaxe Prototyping – Part 3 – Speaker

  1. Hi,

    I’ve a question to ask you because i’m not very good in electronics.
    What is the purpose of using capacitor? I know that it can hold the voltage from the Picaxe but isn’t easier to just connect output pin directly to the speaker.

    Best Regards,

    Vincent Hua Wei Tien

  2. Hi there,
    To be honest, I don’t properly know why its there, I was just following the scematics in the Picaxe manuals. My best guess would be it is to smooth out the harsh sound output of the picaxe.

    The speaker connected directly to the Picaxe did seem to work, as i tried it that way while i was plaing around. i’m not sure if it was a difference in the way the speaker was mounted, but i think the speaker was also a little louder when on the board with the capacitor.

    I hope that helps you,
    Cheers,
    Matt

  3. Hey there,

    The purpose of the capacitor is to block any unintentional DC current that might cause the speaker to burn out / get hot / catch fire / eat the cat. Capacitors block DC current, so putting a little 10uf non-polarised one prevents the PICAXE sound command (which leaves the output high – feeding raw DC into the speaker!!) from damaging the speaker. Hardware design correcting software flaws…tut tut tut. Anyway. That is the reason. As a side note, if you wanted to block AC, you would use an inductor.

    Hope this helps.

    Peter Bridgman

  4. Pingback: Quick Electronics Prototyping / playing « DIY DATA

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