PicoMite: driving a passive buzzer

Author	Message
thwill Guru Joined: 16/09/2019 Location: United Kingdom Posts: 4354	Posted: 10:45am 30 Nov 2022       Thanks for the extra input "overnight", So I had a play with PLAY TONE/SOUND using a speaker salvaged from a musical greetings card and the simple one resistor/transistor amp that was fine (if quiet) so I went back to the "buzzer" and of course to nobody's great surprise that now works too #$@&%*! It's very quiet (compared with the raw PWM approach) and rather clicky but it definitely works and I could swear it was dead as a doorknob despite all my efforts the evening before - Sorry! ... I wonder if it will still be working this evening ?   Volhout said   One of the Russian review comments on this item was that it was a dynamic buzzer 16 ohm coil impedance (loudspeaker) component, not a piezo. I'm pretty convinced that is the case too. Presumably a piezo wouldn't be magnetic and this device is.   Mixtel90 said   Almost all of these things come with a + mark, whether they need it or not. It only actually applies to active devices, although it is used on speakers to show the polarity that causes the cone to move outwards. Used to make sure you get the phasing correct in multiple speaker systems. Thanks Mick, I had wondered why there was a (+) on a speaker when (with my limited understanding) I didn't think it mattered.   Turbo46 said   This site might clear up a bit of what is happening with PWM to audio. Thanks Bill, I've checked it out. My next step will be to build @Volhout's inductor free filter and see what effect that has - I'm just waiting on some capacitors. I'll also get a laptop speaker for the actual project:    https://www.aliexpress.com/item/4001252606114.html How do I choose between a 4R or 8R speaker ... presumably the 8R speaker is quieter and takes less power ? As a thank-you for all your help I hope to put up a quick YouTube recording of my 3 voice/buzzer ragtime choir by the end of the week; I just need to cleanup the code to share. Best wishes, Tom