I just dremelled the flip-cover off my Handspring Treo 300 -- it now
looks roughly like this:

  http://mywebpages.comcast.net/jkassay/treo1.jpg

I need to find a speaker I can put into the case to replace the one that
was part of the flip-cover.  The cavity I have available to put it in is
very small -- the face of the speaker must be no more than 1/4" tall by
1-1/4" wide, and the body of the speaker must be no more than 1/4" deep.
So an oval (rather than circular) speaker is probably the most appropriate.

The old speaker was "8 ohms, 0.2 watts" (written on the back of the speaker).
I don't know much about electronics, but the new speaker either needs to be
the same spec or compatible with it. The old speaker could perform as a
speakerphone, but that's a function I really didn't care about -- so the new
speaker doesn't have to be as loud as the old one.

Thanks!

---

Request for Question Clarification by blazius-ga on 24 Sep 2002 02:38 PDT

Could you please state the dimensions for the available space a bit
more precisely?  By the way, most electronics suppliers give their
dimensions in metric measures, so it would help if you gave the
figures in millimeters.

Hi megacz,

I started by searching for 8-ohm speakers that could handle 0.2 watts.

The smallest circular speaker that I could find which met these
criteria was 13mm diameter and 3.1mm thick:

Kingstate KDM-13008 micro speaker 
http://www.kingstate.com.tw/product/KDM-13008/KDM-13008.gif

Kingstate Electronic Corp. also has the smallest oval-shaped speaker
that I could find. Its face is 20mm by 10mm, and it is 4mm thick:

Kingstate introduces new product: KDO-2010008SN
http://www.kingstate.com.tw/p3/P3-49.htm

If you can find a way to fit one of these tiny speakers into your
Treo, this will be the most straightforward and satisfactory solution.
These speakers are designed for applications such as mobile phones and
PDAs.

Smaller speakers are available, but they are designed for hearing aids
and digital watches. They are "really really really tiny", but the
impedance is usually quite high and the power handling capacity quite
low. The sound level will be low, the distortion relatively high, and
the frequency response may be limited.

Using a speaker with an impedance higher than specified is unlikely to
cause damage to low power equipment, and I'd be quite willing to use
one if this were my Treo. But it's not, and I can't absolutely
guarantee compatibility.

Here are some very small hearing aid speakers. In each case, you can
click where it says "Click here for model chart" and you will see the
range of power and impedance specifications available. Look for ones
that do not need a DC bias.

BK series (6.35 x 4.34 x 3.02 mm)
http://www.emkayproducts.com/html/bk_series.htm

CI series (9.53 x 7.24 x 4.19 mm)
http://www.emkayproducts.com/html/ci_series.htm

EC series (7.59 x 4.34 x 3.73 mm)
http://www.emkayproducts.com/html/ec_series.htm

ED series (6.35 x 4.34 x 3.02 mm)
http://www.emkayproducts.com/html/ed_series.htm

From the above list, you could consider for example the BK-8507. The
impedance varies from 10.7 to 30 ohms according to frequency. Here is
the data sheet for the BK series, and the detailed specification for
the BK-8507:

http://www.emkayproducts.com/assets/images/pdf/BK%20data%20sheet%20-%20Issue%2003.pdf
http://www.emkayproducts.com/assets/images/pdf/BK-8507.pdf

The Electronic Goldmine of Arizona sells a "Tiny Swiss Watch Micro
Speaker" at two for $1. They are 40 ohms, and are 8.9 mm diameter and
5.4 mm thick. You can possibly fit five of these wired in parallel -
this would give an input resistance of 8 ohms. The catalog makes a
comment about "driver required", but that is on the assumption that
you would be using it as a beeper rather than a speaker. Don't expect
good sound quality if used as a speaker - these devices have a marked
resonant frequency which facilitates their use as a beeper.

The Electronic Goldmine - New Arrivals
http://www.goldmine-elec.com/images/Pages004-007.pdf
(on page 6 of their catalog, which is the third page of this PDF file)

I hope you find this range of options useful. I recommend looking into
the two 8-ohm speakers that I mentioned first, to see if there is any
way that you could accommodate them into the case.

Finally, for your convenience, here is a metric conversion table:

   1/8 inch - 3.175mm
   1/4 inch - 6.35 mm
   3/8 inch - 9.525 mm
   1/2 inch - 12.7 mm
   5/8 inch - 15.875 mm
   3/4 inch - 19.05 mm
   7/8 inch - 22.225 mm
   1 inch - 25.4 mm


Additional links:

Kingstate Electronics Corp. home page
http://www.kingstate.com.tw/index.htm

Emkay Products home page
http://www.emkayproducts.com/

Electronic Goldmine home page
http://www.goldmine-elec.com/


Google search strategy:

"miniature speaker OR loudspeaker"
://www.google.com/search?q=%22miniature+speaker+OR+loudspeaker%22

"micro speaker"
://www.google.com/search?q=%22micro+speaker%22

"micro speaker" oval
://www.google.com/search?q=%22micro+speaker%22+oval

"BTE OR ITE applications"
://www.google.com/search?q=%22BTE+OR+ITE+applications%22

"micro speaker" watch
://www.google.com/search?q=%22micro+speaker%22+watch


Regards,
eiffel-ga

Great job!  Thanks!

u can proberly find such a speaker in some of the odler headphones.
try looking at the local thrift /salvation army store. u can proberly
take it out of it. and solder it to the connections. its usually 16 at
shouldn't be a problem.
but "the face of the speaker must be no more than 1/4" tall by 
1-1/4" wide"
could mean its oval or eliptical. the headphone ones are circular 1"
or 1.25"

u can proberly find such a speaker in some of the odler headphones.
try looking at the local thrift /salvation army store. u can proberly
take it out of it. and solder it to the connections. its usually 16 at
shouldn't be a problem.
but "the face of the speaker must be no more than 1/4" tall by 
1-1/4" wide"
could mean its oval or eliptical. the headphone ones are circular 1"
or 1.25"