DIY MP3 radio

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edouble101

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Joined 2011
I would like to build a MP3 radio for my brother as a birthday gift.

I came across this Mp3 decoder on Ebay.
An externally hosted image should be here but it was not working when we last tested it.


I would like to use PE brand 2x100W @ 4 Ohm TK2050 Class-D Audio Amplifier Board.
An externally hosted image should be here but it was not working when we last tested it.


To power the MP3 decoder and the amplifier I am looking at 24 VDC 14.6A 350W Regulated Switching Power Supply.
An externally hosted image should be here but it was not working when we last tested it.


The decoder requires a DC 3.5-5v input. The amplifier requires a DC 10-32v input. I think I can directly wire the amplifier to the power supply. How do I wire the MP3 decoder to that power supply?
 
Pano

Pano

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Joined 2004
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Quick answer, you can't. Not directly. You'll need a 5V regulator for the MP3 section. You can make one pretty easily.

That's a LOT of power supply for that rig. You might be able to find something smaller, cheaper and that has both 24V and 5V. It won't hurt to have a big power supply, but it will take up some space, for sure.

Cool find on the player, BTW.
 
KatieandDad

KatieandDad

Member
Joined 2011
All you need is a simple 78L05 regulator - 3 pin regulator for the MP3 decoder.

If you get yourself a 10A 24V supply for the Class D amp(s), the 78L05 will accept the 24V input and give you 5V for the MP3 part.

Simply look up 7805 regulator datasheet. It can be hooked up Point-to-Point or rigged on a simple Veroboard - they are so easy to use.

If you want to get clever you can try an LM317 which just needs two extra components - again easy to use.
 
KatieandDad

KatieandDad

Member
Joined 2011
I would use a 78M05 or even a 78T05 just to be on the safe side.

The letter in the middle of 78*05 is its current rating. A 78M05 may not have the current capacity that you require. The data on the MP3 decoder doesnt state the current requirement. If you go for the 78L05 you've got 100mA the M is 500mA and the T is 1.5A. (T might even be 3A just read the datasheet - the letter indicates the maximum current)

You'll need to experiment to see if it needs a heatsink.

I'd use the LM317 as it has protection against over current and overtemperature.
 
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E

edouble101

Member
Joined 2011
KatieandDad said:
All you need is a simple 78L05 regulator - 3 pin regulator for the MP3 decoder.

If you get yourself a 10A 24V supply for the Class D amp(s), the 78L05 will accept the 24V input and give you 5V for the MP3 part.

Simply look up 7805 regulator datasheet. It can be hooked up Point-to-Point or rigged on a simple Veroboard - they are so easy to use.

If you want to get clever you can try an LM317 which just needs two extra components - again easy to use.
Click to expand...

Pano said:
Yes, just get yourself a 7805 or 78L05. I think even Radio Shack has them. Very easy to hook up. You'll find tons of info on the web. It's all you need to go from 24V to 5V.
It's got three legs. In, Out and ground. You just need a small cap on the in and out. 24V in, 5V out and ground.
Here's an overview.
LM78M05 - 3-Terminal Positive Voltage Regulators
Click to expand...

KatieandDad said:
I would use a 78M05 or even a 78T05 just to be on the safe side.

The letter in the middle of 78*05 is its current rating. A 78M05 may not have the current capacity that you require. The data on the MP3 decoder doesnt state the current requirement. If you go for the 78L05 you've got 100mA the M is 500mA and the T is 1.5A. (T might even be 3A just read the datasheet - the letter indicates the maximum current)

You'll need to experiment to see if it needs a heatsink.

I'd use the LM317 as it has protection against over current and overtemperature.
Click to expand...

Excellent recommendations! Thank you very much.

I am researching the LM317 and have found this video helpful.

Should the heat generated from the LM317 with a 24v input and a 5v output be a concern?
 
E

edouble101

Member
Joined 2011
Will this power supply work? If I could use an external power supply that would be great. Would I just run the - and + to a distribution strip (one set of power to the amp another to the LM317 circuit)inside the MP3 cabinet?
41bueZPJIZL.jpg
 
H

Hakimi

Member
Joined 2010
for your simplest way to power-up MP3 module is 5V right ?
If me, I will use any USB charger which the output is 5V 500mA-1A
and for amplifier, just use normal transfomer with caps. rather using lappy PSU which is based Switching Mode Power Supply (SMPS)...

Just an opinion...
 
E

edouble101

Member
Joined 2011
Hakimi said:
for your simplest way to power-up MP3 module is 5V right ?
If me, I will use any USB charger which the output is 5V 500mA-1A
and for amplifier, just use normal transfomer with caps. rather using lappy PSU which is based Switching Mode Power Supply (SMPS)...

Just an opinion...
Click to expand...

Thanks for the tips. I decided to use a smaller internal amplifier. This allows me to use an outboard 12v power supply that I will step down with a 7805 for the 5v.

Thank you all for your help.
 
KatieandDad

KatieandDad

Member
Joined 2011
edouble101 said:
Excellent recommendations! Thank you very much.

I am researching the LM317 and have found this video helpful.

Should the heat generated from the LM317 with a 24v input and a 5v output be a concern?
Click to expand...


The data for the MP3 decoder is insufficient to know what the current draw will be.


Generally the lower the voltage, the more current is required.

In that case the LM317 might need a heatsink.
 
KatieandDad

KatieandDad

Member
Joined 2011
There is a mention of 3W POWER RELEASE - I've no idea what our Oriental friends are talking about there.

If we double that for a guestimate - 6W and add a few watts to 10W we are looking at 2A at 5V.

In this case the LM317T is going to need a serious heatsink.

24-5 = 19V. 19V x 2A = 38W

The heatsink would cost more than a low voltage transformer dedicated to producing the 5V.

Having said that. There are a LOT of old computers on the scrap heap that have heatsinks that are used to dissipating about 60W.

Be careful of USB power supplies - we dont know what current this thing needs.
 
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E

edouble101

Member
Joined 2011
Hakimi said:
welcomes...
previously i have built an intergrated amplifier with preamp and MP3 player
have a look.. https://www.facebook.com/media/set/?set=a.1502265835751.2069666.1207371895&type=3&l=075c4799a2

This set built for Final Year Project for my diploma..

regards..
Click to expand...

Cool project :D

KatieandDad said:
There is a mention of 3W POWER RELEASE - I've no idea what our Oriental friends are talking about there.

The 3w power release is the onboard amplification for speakers per channel.

If we double that for a guestimate - 6W and add a few watts to 10W we are looking at 2A at 5V.

In this case the LM317T is going to need a serious heatsink.

24-5 = 19V. 19V x 2A = 38W

The heatsink would cost more than a low voltage transformer dedicated to producing the 5V.

Having said that. There are a LOT of old computers on the scrap heap that have heatsinks that are used to dissipating about 60W.

I picked up a 7805. I will be stepping down a 12v power supply to 5v. The MP3 decoder and another gizmo I am throwing in the mix shouldn't draw more than 1.5A.

Be careful of USB power supplies - we dont know what current this thing needs.
Click to expand...

I ended up buying a Parts Express MP3 decoder a 12v 2a powers supply and a Dayton Audio 15w x 2 amplifier. I also picked up a 7805 and a few other things that you guys will have to wait to see :D

Once I get this project started I will post pics of my progress (and probably some more questions) :cheers:
 
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