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WhiteWizzard
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Posted: 01:07pm 28 Oct 2015

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Hi,

I am after some help please, and do hope that there are some TBS members out there with some good ideas . . .

Does anyone know of an amplifier chip/circuit (that will ideally draw no more than 50mA) capable of playing an output from an MP3 player? i.e. similar to the type of sound outputted from a tablet or phone.

I have a MM circuit that needs to be able to play MP3 files that comprise of speech. I don't need hi-fi quality, but it does need to be clear as to what the MP3 speech file is saying. The MP3 player is already obtained - it is just the 'amp' part I need help with.

Speakers need to be tiny - I currently have some 1W capable; piezo option would be ok if sound output is good enough.

Chip can be SPI or I2C controlled as it will be connected to the MM.

So does anyone have any ideas or recommendations that I can look into?

Many thanks . . . .

WW

HankR
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Joined: 02/01/2015
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Posted: 01:34pm 28 Oct 2015

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WhiteWizzard said

Chip can be SPI or I2C controlled as it will be connected to the MM.

WW

Sounds like it HAS to be controlled by the MM.

Do you need to control volume, put the audio amp to sleep, or have
other such requirements?

Hank

Grogster

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Posted: 02:06pm 28 Oct 2015

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I have used quite a few of these modules in my projects. 5v supply.

Perfect if you just need a bit of volume for alarms etc. There is also a version without the volume/on/off control here.

These are not digitally controlled. If that is something you specifically need, then that could prove more difficult if you need it to be small.

Smoke makes things work. When the smoke gets out, it stops!

viscomjim
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Posted: 02:23pm 28 Oct 2015

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Hi WW, I use quite a bit of THESE because they are cheap and sound great. I also use a lot of THESE if I need stereo amplification. Neither one of these is controlled by I2C or SPI.

Could you give a bit more detail about the MP3? The little guy that CG uses for his audio shield has serial control, you can control the volume, and 6 eq settings and it has a small 3W amp, all controlled using COM.
I use a few of these and they work real well.

EDIT... Sorry I just got home and skimmed your original request. The suggestions above won't fit the bill. Next time I'll read slower....Edited by viscomjim 2015-10-30

HankR
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Posted: 03:05pm 28 Oct 2015

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viscomjim said The little guy that CG uses for his audio shield has serial control, you can control the volume, and 6 eq settings and it has a small 3W amp, all controlled using COM.

That sounds very interesting. Could you please name the IC involved?

Even "mistaken" posts can be very helpful.

Hank

viscomjim
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Posted: 03:10pm 28 Oct 2015

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Hi Hank, HERE is the link to CG's shield. It uses the MP3TF16P unit. Serial comms.Edited by viscomjim 2015-10-30

Grogster

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Posted: 03:22pm 28 Oct 2015

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Those MP3TF16P units have a built-in amp, so that could be a nice solution.
Good thinking, Jim!

@ WW - I have about 10 of these modules. If you would like one to play with, flick me a PM. I have never got around to using them, as I settled on the Catalex one instead, but I am sure they are floating about here somewhere...

Smoke makes things work. When the smoke gets out, it stops!

HankR
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Posted: 03:42pm 28 Oct 2015

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viscomjim said It uses the MP3TF16P unit. Serial comms.

Thank you Jim.

Just doing a quick search on this item (not the entire CG board), I'm getting a clear impression that the audio amp has no uC control, only the wave player IC on the MP3TF16.

I had a screen display showing the complete TF16 circuit, but I lost it trying to enlarge it. Looked like Chinese part numbers for both important ICs. Manual does not show any "internal" schematic, so that's no help.

A digitally controlled audio amp (capable of driving a least a small speaker) may be scarce or even unobtainium. I could regret voicing that statement very soon.

MicroBlocks

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Posted: 03:47pm 28 Oct 2015

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It might be enough to just use a digital potentiometer to control the volume digitally. Those are often I2C.
The amplifier circuit can then be just a standard one you can find all over the internet.
Or does it need more digital control?

Microblocks. Build with logic.

viscomjim
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Posted: 03:50pm 28 Oct 2015

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How bout' THIS

http://www.ti.com/product/tpa2016d2Edited by viscomjim 2015-10-30

viscomjim
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Posted: 04:04pm 28 Oct 2015

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Holy Cow Grogster, I just noticed you have 3237 posts! WOW!!!!

Grogster

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Posted: 04:05pm 28 Oct 2015

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THAT is an interesting module - I might have to get one to play with myself, just for the hell of it. Being I2C, it will give me yet another I2C thing to practise on.

I think this module would be just what WW is looking for, if you will pardon my presumptuousness for a moment.

Smoke makes things work. When the smoke gets out, it stops!

Grogster

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Posted: 04:06pm 28 Oct 2015

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viscomjim said Holy Cow Grogster, I just noticed you have 3237 posts! WOW!!!!

Yes, I am quite addicted to this forum.

Beer substitute do you think?(rhetorical)

Smoke makes things work. When the smoke gets out, it stops!

viscomjim
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Posted: 04:08pm 28 Oct 2015

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Most likely... I wonder if you hold the record...

Pretty soon you will be the I2Cster...

How are you making out on your I2C sound chip????

Edited by viscomjim 2015-10-30

MicroBlocks

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Posted: 04:16pm 28 Oct 2015

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One of the smallest i can find with digital volume/mute control is http://www.amplifiercircuit.info/2014/09/1-w-btl-audio-amplifier-with-digital.html

Microblocks. Build with logic.

MicroBlocks

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Posted: 04:17pm 28 Oct 2015

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viscomjim said Most likely... I wonder if you hold the record...

http://thebackshed.com/forum/members.asp?SF=&GID=0&SO=PT

Ha! I am in the top 10. (In quantity at least)

Edited by MicroBlocks 2015-10-30

Microblocks. Build with logic.

Grogster

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Posted: 04:23pm 28 Oct 2015

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@ Jim - I will soon have everything wired up, so can start to play with the I2C on that in earnest then. I have polled the chip(from the command line), and it responds, so that is a good sign. Keep your eye on the thread about it. That is where I will post any updates.

Smoke makes things work. When the smoke gets out, it stops!

matherp
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Posted: 09:40pm 28 Oct 2015

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This has digital up/down volume control and is ready built

WhiteWizzard
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Posted: 10:26pm 28 Oct 2015

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THANKS for all the replies and suggestions.

Sorry for not making it clear before about SPI/I2C. Ideally I want to be able to set a volume setting from software (rather than an up & down input). No need for shutdown BUT it must have low standby current.

The trouble with the small amp modules (i.e. 1W+1W) is that they draw a lot of power when making 'sound'. I have measured several hundred mA's which is more than I have available.

Currently I am driving a Piezo buzzer just to make 'beeps'. The circuit draws no more than 18mA and is 'loud'.

However, I now want my device to be able to play 'music' from the output of an MP3 module but have no more than 75mA available to drive amp & speakers.

I do not need it to be loud. Stereo would be nice, but mono is ok.

Can a piezo be driven somehow with an 'analogue' signal? Any other ideas would be welcome . . . .

Thanks again,
WW

Grogster

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Posted: 10:41pm 28 Oct 2015

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75mA is not much current to play with, Mr. Wizzard.

Not saying it can't be done, but even the class-D amps start sucking more then that when asked for more then a few hundred milliwatts or so.

I do like the adafruit unit though, and if you did not drive it's output very hard, you could probably do it all within 75mA or so - you'd have to try it and see.

Smoke makes things work. When the smoke gets out, it stops!

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