Go Down

Topic: Arduino MKR Zero - amplifier - power source (Read 889 times) previous topic - next topic

DrDooom

Hello everybody,

I am currently using the Arduino (MKR Zero) to realize a mono audio output with a speaker. It should become a special player for my daughter.

It is important to know that I have almost no experience in electrical engineering, but a lot of fun !!!  :smiley:

Currently I read WAV files (44.1khz, 16 bit, mono / stereo) and output them on the DAC with 10 bit (0 - 3.3V). Works so far with an in-ear headphone. I do not use the AudioZero library because it uses the DAC with 10 bit, but only supports WAV files with 8 bit samples (uint8_t * __ WavSamples;) and does not allow any tasks besides playing.

For further testing, I would like to operate a small 8 ohm speaker with 1 W. Therefore, the plan is to use an audio amplifier IC.

I have already bought two different ICs weeks ago (UA741 CN, NE5534 AP). Since I've read that the UA741 is bad and the gain / balancing with the NE5534 does not work really well/easy, my electronics dealer around the corner recommended the TDA2050 to me. This would be sold most often and offers very good performance. I bought a couple of the ICs.
Here is a datasheet:
www.st.com...../en.CD00000131.pdf

My problem is that I can not interpret the information from the Internet well enough and also can not interpret the found schemas well (Sorry, I'm a software developer). Unfortunately I understand only representations like this here with the LM386:
By the way, the LM386 seems to cause distortion and the IC was not available any more.

According to the information found so far, for the TDA2050 i need a power source with + 5V and -5V or, for example, + 12V and -12V!

As a power supply, I would like to use a 5V or 12V source. If necessary, a battery. However, the power supplies I know have only + and GND but no negative V!

Hence my question:
1. How do I get a negative voltage from my power supply (+ 5V or + 12V and GND)?
2. Is someone familiar with a simple representation of a TDA2050 schematic (such as the PNG above)? Or would it be possible for someone to do such a thing?
3. According to the linked PDF on page 2, Figure 2. Pin connections should the IC package connect to pin 3 (negative voltage V-)? Can that be right?


I hope someone here, who knows the electronics better and is helpful. I would not report here otherwise.

Thank you, DrDooom.

DVDdoug

#1
Mar 07, 2018, 07:35 pm Last Edit: Mar 07, 2018, 08:10 pm by DVDdoug
Quote
By the way, the LM386 seems to cause distortion
Most likely you've got too much gain and the amplifier is getting driven into distortion.  You only need a (voltage) gain of 2 - 4, if you need any gain at all.    (You do  need power & current gain, so you do need an amplifier even if you don't need voltage gain.)   I believe the minimum gain setting for the LM386 is 20.   A Voltage Divider on the input (in addition to the volume control pot) should help.   (The chip itself has "good specs" and under the right conditions there should be no audible distortion.)

Quote
and the IC was not available any more
I assume you have one, since you're complaining about distortion, but if you are in the U.S. Digikey has 8000 in stock.

You can test the amplifier by plugging-in your iPod or phone, or a CD player, etc.    And, you can test the sound quality from your Arduino by connecting powered computer speakers, or by plugging into your stereo or TV, etc.


Quote
1. How do I get a negative voltage from my power supply (+ 5V or + 12V and GND)?
You can get a DC-DC converter, but it's more practical to use an amplifier that works from a single supply. 
There are lots of amplifier chips and you should be able to find some that work from single supplies.


DrDooom

I reply to this thread because I was written about pm.

I have solved the problem with a VS1053 board. The board accepts WAV, OGG, MP3, etc RAW data and has an integrated 2048 byte buffer. The audio quality is good (for me) and I can connect a headphone or an audio amplifier with a 3.5mm jack.

Go Up