The Model Railroad community refer to 'iphone speakers' and also 'sugar cub= e' speakers. These both have significant sound output levels as the back of= the speaker is sealed. Sorry I don't have any direct links, but I know that at least one of these = styles has been obtained from eBay. -----Original Message----- From: piclist-bounces@mit.edu On Behalf Of Art Sent: 24 October 2018 08:51 To: Microcontroller Public Subject: [OT] Loud/small speaker needed Hi All, I have a 12F1840 that will put out various frequency tones when complete, s= quare waves with a 2N3904 amplifier transistor with Vcc of 4.5 VDC. I need a nearly microscopic speaker of some sort that will put out enough n= oise to be heard easily. Cellphones have microscopic speakers and put out e= nough volume when used in speakerphone mode, so I didn't worry about sourci= ng a speaker for my project. However, I now realize that I can't locate one= of these beasts. I don't need high fidelity sound, but I need something loud enough to be he= ard in the next room at least well enough to alert me that the 12F1840 has = been activated. Budget is almost nil. Size is as small as possible, 8mm by 8mm by 3mm would= fit in my enclosure. I can go a bit larger than that with a PCB redesign. Any suggestions? TIA. -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t --=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 .