DIY amplifier+loudspeaker

[Man-wai Chang]

I only need a very very basic speaker, powered maybe by AA batteries,
that amplifies the 3.5mm audio output from the iPod Touch.

Is this going to be cheap?

Could I just connect a small buzzer to it?

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[Daniel Mandic]

Man-wai Chang wrote:

I only need a very very basic speaker, powered maybe by AA batteries,
that amplifies the 3.5mm audio output from the iPod Touch.

Is this going to be cheap?

Could I just connect a small buzzer to it?

I would recommend a chinese product. You get more for the money, it's
finished (case) and plug&play ready with connectors, (electronic)
parts, cables, loudspeakers...

Headset is the better option, IMO. You can still hear the environment
but have your radio, sample etc. playing.


--
Daniel Mandic

 

[Man-wai Chang]

I would recommend a chinese product. You get more for the money, it's
finished (case) and plug&play ready with connectors, (electronic)
parts, cables, loudspeakers...

Not cheap enough, I think. Something like US$2-3 would be great...

Headset is the better option, IMO. You can still hear the environment
but have your radio, sample etc. playing.

Wanna hear it while bathing.

--
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[Daniel Mandic]

Man-wai Chang wrote:

Not cheap enough, I think. Something like US$2-3 would be great...

You are at the source. 2-3$ (new).... why not.


--
Daniel Mandic

 

[Don Klipstein]

In article <itkcf8$tca$1@dont-email.me>, Man-wai Chang wrote:

I only need a very very basic speaker, powered maybe by AA batteries,
that amplifies the 3.5mm audio output from the iPod Touch.

Is this going to be cheap?

Could I just connect a small buzzer to it?

Don't use a buzzer.

This sounds to me like a job for an entry-level DIY-er trying to work
with actual electronics to work with:

An LM386, specifically LM386N-1 IIRC, a "cheap-and-dirty" hobbyist
audio power amplifier in low power range and good for 6V and 9V use, 12V
with some care.

Use any 8-ohm loudspeaker at least 2 inches in diameter with 5V to 9V
power supply, such as USB power, a 5V regulated power supply, 4 AA cells
or a 9V battery. Even if you push things very loud, the LM386 tends to
survive and even the crappiest loudspeakers won't completely die quickly,
and most won't get damaged at all.

LM386N-1 is the version that Radio Shack sold, and fair chance still
sells. Radio Shack catalog number 276-1731, may not be available in all
stores. Other parts needed withy it may not be available in all stores.
I recommend looking for Radio Shack stores with 4 sets of drawers of small
parts, as opposed to 2 or some other smaller number.

The lead-free version is available at Digi-Key, get to that here:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=LM386N-1-ND

(Minimum order or falling-short-of-minimum-fee and shipping charges
apply.)

Datasheet for National Semiconductor LM386 is here:

http://www.national.com/ds/LM/LM386.pdf

Pinout (viewed from above) of LM386 is in the lower-right corner of the
1st page of this PDF.

The schematic of my favorite way to use this (simplest) is in the
upper-left corner of Page 5 of this PDF.
The capacitor mentioned as 250 uF can be larger, though I see little need
to use more than 1000 uF.
The capacitor mentioned as .05 uF can be the more-common .047 uF. I
have successfully used .1 uF, but I recommend staying in the range of
nominally .047-.1 uF.

===============================================

If you want a loudspeaker to use with the LM386 that I especially like:
Radio Shack 40-1909. May not be easy to get now, may be obsolete. It's
very much an all-purpose lower-power 5" fullrange loudspeaker with fairly
decent efficiency and some capability of impressive bass response.
Put it in a box of about shoebox size and made of wood at least 1/2
inch thick - amazing even without a port. Bass response is rather decent
in a .23 cubic inch box against a wall, with -3 dB at 108-110 Hz. It even
works well in a .125 cubic foot box - -3 dB is at about 120 Hz. In a .1
cubic foot box, its -3 dB bass point is about 126-127 Hz.

In a .63 cubic foot box with port tuning of 62 Hz, the bass -3dB point
is 53 Hz. That is good bass response for a box that size with 91 dB @
1W, 1m with a fullrange or woofer of any size.

Details including box and port dimensions at:

http://donklipstein.com/1909.html
--
- Don Klipstein (don@misty.com)

 

[Man-wai Chang]

Thanks

--
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/ v \ Simplicity is Beauty! May the Force and farces be with you!
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On Mon, 20 Jun 2011 00:05:45 +0000 (UTC), Don@DonKlipstein.com (Don
Klipstein) wrote:

LM386

Wow, they still make that? I've got a few in my parts drawers.

I'm using a LM3909 for a project today (sense when the AC compressor
is running via a "self powered" current transformer). One of three
obsolete parts...

Very useful dinosaur in my opinion. Likewise the LM386.

 

[Jasen Betts]

On 2011-06-20, default <default> wrote:

On Mon, 20 Jun 2011 00:05:45 +0000 (UTC), Don@DonKlipstein.com (Don
Klipstein) wrote:

LM386

Wow, they still make that?

yeah, (as long as you don't try to get them from mouser! all the others
have em, even Rat shack.)



--
⚂⚃ 100% natural

 

[Man-wai Chang]

You are at the source. 2-3$ (new).... why not.

After a bit of search, I really found a HK$15 speaker in a famous Sham
Shui Po street of Hong Kong. The invoice said it's a Sanyo, but I failed
to find that word on the silver label behind the speaker. Model Number
is SA-WSP001. Made in China.

The stereo speaker can be powered from USB or 3xAAA batteries. The
bundled cables and plugs are of poor quality. Anyway, it works.

I guess I would not need to build one for a while.

--
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[Daniel Mandic]

Man-wai Chang wrote:

You are at the source. 2-3$ (new).... why not.

After a bit of search, I really found a HK$15 speaker in a famous
Sham Shui Po street of Hong Kong. The invoice said it's a Sanyo, but
I failed to find that word on the silver label behind the speaker.
Model Number is SA-WSP001. Made in China.

1 and a half Euro . You can can get a pair of 3.5mm headphone-jack
and 1m stereo-cable for that money here...

The stereo speaker can be powered from USB or 3xAAA batteries. The
bundled cables and plugs are of poor quality. Anyway, it works.

I have bought a low-level amp+speakers, made in China of course, for
100HK$. Full crap ;-) and one side of the speakers does not work, I
guess it's the jack socket...

I guess I would not need to build one for a while.

Not for that money.


--
Daniel Mandic

 

[Man-wai Chang]

1 and a half Euro . You can can get a pair of 3.5mm headphone-jack
and 1m stereo-cable for that money here...

That will be my next search!

100HK$. Full crap ;-) and one side of the speakers does not work, I
guess it's the jack socket...

Very very likely!

Not for that money.

A flat 8W speaker cone needs about HK$6 here.

--
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/ v \ Simplicity is Beauty! May the Force and farces be with you!
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