...is it not just Gnd and V+ usually?
I don't understand why they are here
the tech drawing says "Speaker & Receiver", so perhaps there are two coils?
Hi,I have just bought a little piezo speaker like that : http://www.newark.com/pdfs/datasheets/spc/25R0936.pdfThe problem is there are 4 pins to connect at the back of the speaker, and I don't understand why they are here... is it not just Gnd and V+ usually?Thank you.
it's probably just for better mechanical stability for mounting to the PCB
"+" and "-" on a speaker are there for phasing purposes. On a speaker this small it wouldn't really make much difference, but on large speakers where they are not phased properly makes for a big loss in bass.A way to test the the result of phasing is to take and drive 2 speakers, side by side, from the same source and reverse the phasing on one and listen for the difference in the quality of the sound. One effect from 2 speakers that are closely spaced but different in phase is that the sound will be quieter at a distance as when on speaker is pushing air, the other is pulling and thus they will tend to cancel out.
Fun hobby until the whole world seemed to learn about the golden age of hi-fi equipment and the thrift store finds dried up.