On Mon, 29 Oct 2018 at 06:17, Art wrote: > I have found the answer, and it is much closer and available than I ever > dreamed of! > Mouser has the best candidate, but I need to test it, so I have one on > order. It's 10 mm dia by 3mm thick, PN =3D SM101208-1. I hope it's loud > enough to meet my needs....or that it's not to loud-my project doesn't > include a volume control (due to size limitations). > > Data sheet here: https://nz.mouser.com/datasheet/2/683/SM101208-1-358991.pdf 8 Ohms impedance, 150 mW max normal. That requires ~~=3D a 2.2 V peak to peak sine wave. Current of about 150 mA mean, so your port pin will not drive it to full power (unless PICs have grown much gruntier I/O muscles of late). They quote 82 dB SPL at 10 cm - presumably at 150 mW in. So at 10 dB (10% of power) down in power input (probably [tm] around what the PIC can achieve) your SPL will be down around 3x and perceived loudness to human ear down by a factor of about 2x. [[E&OE] which may well exist in even this simple case :-) ]. ie - "should be reasonable". Claimed noise levels from various sources vary somewhat amon sources, but *= some of these * * will help And this useful table http://www.sengpielaudio.com/Cause-Effect-Perception.gif from this page, which "explains it all quite well" http://www.sengpielaudio.com/calculator-levelchange.htm Russell * Google image search: https://www.google.co.nz/search?q=3Dsound+levels+db&num=3D40&tbm=3Disch&tbo= =3Du&source=3Duniv&sa=3DX&ved=3D2ahUKEwi4j4fptqreAhXWfX0KHU5XBGUQsAR6BAgBEA= E&biw=3D1680&bih=3D908 Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .