[OT] Loud/small speaker needed

[Art]

Hi All,

I have a 12F1840 that will put out various frequency tones when
complete, square 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 noise to be heard easily. Cellphones have microscopic speakers
and put out enough volume when used in speakerphone mode, so I didn't
worry about sourcing 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
heard 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.

[Richard Prosser]

Use the speaker (& case) from an old cellphone?
RP

Post by Art
Hi All,
I have a 12F1840 that will put out various frequency tones when
complete, square 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 noise to be heard easily. Cellphones have microscopic speakers
and put out enough volume when used in speakerphone mode, so I didn't
worry about sourcing 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
heard 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.
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[Art]

Hi All,

I have found the answer, and it is much closer and available than I ever
dreamed of! And, once I used 'micro speaker' for a search term, the
internet yielded the answer!

My limited space requirements preclude any use of an air
horn-unfortunately. And, old cellphones (non-smart phones) don't yield
good results, probably due to not being designed for speaker phone
use-or using old technology speakers. I've tried 2 of them from very old
flip phones.

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 = 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).

A close second choice is the DMT-1206, although the combination of
diameter and height makes it a no go for my project.

My PIC (PIC12F1840) has a fixed output from pin 3, I hope to drive the
speaker directly-without an amp, but that's probably unrealistic.

Again, thanks to all who commented and offered guidance!

Art

Post by Art
Hi All,
I have a 12F1840 that will put out various frequency tones when
complete, square 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 noise to be heard easily.

[RussellMc]

Post by Art
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 = 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).

https://nz.mouser.com/datasheet/2/683/SM101208-1-358991.pdf

8 Ohms impedance, 150 mW max normal.
That requires ~~= 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
<https://www.google.co.nz/search?q=sound+levels+db&num=40&tbm=isch&tbo=u&source=univ&sa=X&ved=2ahUKEwi4j4fptqreAhXWfX0KHU5XBGUQsAR6BAgBEAE&biw=1680&bih=908>*
* will
help

And this useful table
Loading Image...

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=sound+levels+db&num=40&tbm=isch&tbo=u&source=univ&sa=X&ved=2ahUKEwi4j4fptqreAhXWfX0KHU5XBGUQsAR6BAgBEAE&biw=1680&bih=908

Russell

[Forrest Christian (List Account)]

oops hit send just as I noticed I said 'speaker' when I meant 'piezo'.
Note that many of these aren't flat on frequency response (see the graph
in the image I linked), but they're perfectly servicable as a beeper/buzzer
as long as you know that some frequencies are better than others.

On Wed, Oct 24, 2018 at 2:43 AM Forrest Christian (List Account) <

https://www.allelectronics.com/item/pe-52/mini-tone-transducer/1.html
[image: image.png]
I think the term you're looking at is 'transducer' or 'speaker'. All
electronics have quite a few on their website, that's just the first one I
found.

Post by Art
Hi All,
I have a 12F1840 that will put out various frequency tones when
complete, square 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 noise to be heard easily. Cellphones have microscopic speakers
and put out enough volume when used in speakerphone mode, so I didn't
worry about sourcing 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
heard 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.
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http://mailman.mit.edu/mailman/listinfo/piclist

--
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: [phone] | Address: 3577 Countryside Road, Helena, MT 59602
<http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux>

--
*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: [phone] | Address: 3577 Countryside Road, Helena, MT 59602
***@imach.com | http://www.packetflux.com
<http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux>
<http://twitter.com/@packetflux>

[AB Pearce - UKRI STFC]

The Model Railroad community refer to 'iphone speakers' and also 'sugar cube' 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-***@mit.edu <piclist-***@mit.edu> On Behalf Of Art
Sent: 24 October 2018 08:51
To: Microcontroller Public <***@mit.edu>
Subject: [OT] Loud/small speaker needed

Hi All,

I have a 12F1840 that will put out various frequency tones when complete, square 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 noise to be heard easily. Cellphones have microscopic speakers and put out enough volume when used in speakerphone mode, so I didn't worry about sourcing 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 heard 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.


--
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[m***@tutanota.com]

You might try a piezo speaker like used on mother boards.  Terrible fidelity but plenty loud if you drive them near resonance (i.e. vary the pitch and find the sweet spot).  For something that small you might need a bare piezo disc, possibly mounted with a dab of silicone on the edge.  That's a very challenging "smallness" for anything found laying around.

Post by Art
Hi All,
I have a 12F1840 that will put out various frequency tones when
complete, square 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 noise to be heard easily. Cellphones have microscopic speakers
and put out enough volume when used in speakerphone mode, so I didn't
worry about sourcing 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
heard 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.
--
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[AB Pearce - UKRI STFC]

Post by m***@tutanota.com
You might try a piezo speaker like used on mother boards.  Terrible fidelity but plenty loud if
you drive them near resonance (i.e. vary the pitch and find the sweet spot).  For something
that small you might need a bare piezo disc, possibly mounted with a dab of silicone on the
edge.  That's a very challenging "smallness" for anything found laying around.

If using a piezo disk then it is probably worth finding a plastic horn like used in smoke alarms for it.

[m***@tutanota.com]

Actually, all sound drivers benefit from a horn load.  They provide a partial impedance match between the driver (much denser than air) and the air.

Post by AB Pearce - UKRI STFC

Post by m***@tutanota.com
You might try a piezo speaker like used on mother boards.  Terrible fidelity but plenty loud if
you drive them near resonance (i.e. vary the pitch and find the sweet spot).  For something
that small you might need a bare piezo disc, possibly mounted with a dab of silicone on the
edge.  That's a very challenging "smallness" for anything found laying around.

If using a piezo disk then it is probably worth finding a plastic horn like used in smoke alarms for it.
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[Bob Blick]

Hi Art,

If you only need one, you might try tearing apart some old cellphones until you find one that is the right size.

Other than that, this is the smallest loud-ish speaker that you're likely to find, it's 12mm dia x 8.2mm:
https://www.aliexpress.com/item/5PCS-Lot-Passive-Buzzer-AC-12MM-8-5MM-12085-16R-Resistance-3V-5V-9V-12V-In/32503620431.html

It is a dynamic speaker, not a piezo.

Piezos that small have limited use below 4KHz. I've done a bit of experimenting with 27mm diameter piezos, and those are quite usable below 2KHz. I cut down a bottle cap and glue the disk to the inner ridge(the part that seals to the inside of the bottle mouth) of the cap, about 20mm diameter for a 27mm disk. Do not support the disk at the edge! You also need to drill a sound hole in the cap. This works fine if you want to produce multiple frequencies. To get the loudest sound from a piezo you need to create a Helmholtz resonator, and that requires the perfect volume and hole diameter, and then it only works at the resonant frequency, but it's easily 6db louder than a random bottle cap.

Cheerful regards, Bob

________________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Art
Sent: Wednesday, October 24, 2018 12:50 AM
To: Microcontroller Public
Subject: [OT] Loud/small speaker needed

Hi All,

I have a 12F1840 that will put out various frequency tones when
complete, square 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 noise to be heard easily. Cellphones have microscopic speakers
and put out enough volume when used in speakerphone mode, so I didn't
worry about sourcing 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
heard 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.