Make your own Low Budget Bluetooth Music System || OpAmp

**Wireless Music Station in Bathroom: A DIY Project**

I recently found a dirt cheap Bluetooth music receiver on Ebay for around 4 to 5 bucks, and since I had this pretty high quality speaker laying around from a previous project, I thought: Why not fuse those two together and build a wireless music station for my bathroom?

**The Electronics**

All the electronics disappear in the ceiling and only the speaker is visible. It works like a charm, and produces high quality sounds.

First of all, let's take a look at the receiver module. The most important thing to know about it is the model name and the pairing code. I gave it power via USB and paired my phone with it. Now I connect ground to the minus terminal of the speaker and one channel to the plus terminal, and we have sound. Great!

But you may already think that I'm an idiot, because that is not the way this works. The sound of the speaker is really quiet, and when we take a look at our signal on the oscilloscope, we can see that the max voltage peak to peak is only around 200 millivolts.

**The Problem: Low Volume**

Now let's think about it. I want louder music, which means more power on my speaker. And power equals voltage multiplied by current, and current equals voltage divided by resistance. Now combine those two, and we can see that power equals voltage squared divided by resistance. This is a 4 ohm speaker, which means we cannot change the resistance, so we have to increase the voltage.

**The Solution: Amplifier**

And that is where we use amplifiers. But there are so many different kinds of them. There are A, B, A, B, C, D, E, F, G types! It makes your head spin!

So let's take a look at the most simple and famous one: The LM386 OpAmp. You can build a basic audio amp with practically no external ports, just some smoothing capacitors. And it does work in the end, as you can clearly hear.

But the distortion of those is not the greatest, and I do not want such problems in my ceiling. So let's Take a look at the NE5534 OpAmp. This takes some more parts to get the same functionality in the end, but it is worth it.

**The Output Stage**

Now, here's a problem with those kinds of amplifiers. They are popular on Instructables, for example, but there, they use them to drive speakers directly. And this may work for small 8 ohm speakers, but in our case, at some point, the audio quality just sucks and collapses.

The reason is simple. These guys can amplify the voltage without a problem, but they cannot output enough power the speaker needs. That is why I have to build an output stage for this amplifier, which can handle more output power.

I went with this class B transistor amp, which does a pretty decent job for its simplicity.

**The Amplifier**

Okay, I think I'm going to use this design for my amplifier. So let's solder all the parts to a PCB. I made this layout for the board to make things easier.

And while I'm doing this, let me tell you that this is a pretty simple amp, which does not feature the very best quality. And if you think that you lack the skills it needs to build your own amp, you can always buy a premade kit.

**The Bluetooth Module**

Now the amp is done but as always I forgot something. The Bluetooth module of course! I open its case very carefully, and immediately saw where to hook up the power.

So I added an LM7805 regulator to provide 5V for the Bluetooth module. And also I used a voltage regulator to provide 12V for the 230V->12V adapter.

**The Final Touches**

Now let's head to the bathroom and I will start to determine the location of my speaker. And use this special saw to cut out this beautiful circle.

When I was sure that the speaker will fit later, I went ahead and turned off the lights and also turned off the circuit breaker. Please don't forget that! 230 volts can kill you!

Then I used two terminals to get some power from my LED lights, and connect those to the 230V input of my 12V adapter and my 5V adapter.

Now I put all the components into the ceiling and secured my speaker with screws. And from now on, I can enjoy the awesome sound of my speaker inside my bathroom, and so can you if you build this too!

If you liked this project, why not give it a thumbs up? Be sure to check out my other videos and subscribe to stay up to date With my channel . Stay creative, and I will see you next Time!

WEBVTTKind: captionsLanguage: enI recently found this dirt cheap Bluetooth music receiver on Ebay for around 4 to 5 bucks,and since I had this pretty high quality speaker laying around from a previous project,I thought: Why not fuse those two together and build a wireless music station for my bathroom?All the electronics disappear in the ceiling and only the speaker is visible.It works like a charm, and produces high quality sounds.Now I will show you how to make your own.(Neat Music)First of all, let's take a look at the receiver module.The most important thing to know about it is the model name and the pairing code. I gave it power viaUSB and paired my phone with it.Now I connect ground to the minus terminal of the speaker and one channel to the plus terminal, and we have sound. Great!But you may already think that I'm an idiot,because that is not the way this works.The sound of the speaker is really quiet, and when we take a look at our signal on the oscilloscope,we can see that the max voltage peak to peak is only around 200 millivolts.Now let's think about it. I want louder music, which means more power on my speaker.And power equals voltage multiplied by current, and current equals voltage divided by resistance.Now combine those two, andwe can see that power equals voltage squared divided by resistance.This is a 4 ohm speaker, which meanswe cannot change the resistance, so we have to increase the voltage and that is where we use amplifiers.But there are so many different kinds of them. There are A, B, A, B, C, D, E, F, G types!It makes your head spin! So let's take a look at the most simple and famous one:The LM386 OpAmp. You can build a basic audio amp with practicallyno external ports, just some smoothing capacitors. And it does work in the end, as you can clearly hear.But the distortion of those is not the greatest, and I do not want such problems in my ceiling.So let's Take a look at the NE5534 OpAmp.This takes some more parts to get the same functionality in the end, but it is worth it. Now, here's a problem with those kinds of amplifiers.They are popular on Instructables, for example, but there, they use them to drive speakers directly.And this may work for small 8 ohm speakers, but in our case, atSome point, the audio quality just sucks and collapses. The reason is simple. These guys canAmplify the voltage without a problem, but they cannot output enough power the speaker needs.That is why I have to build an output stage for this amplifier, which can handle more output power.I went with this class B transistor amp, which does a pretty decent job for its simplicityOkay, I think I'm going to use this design for my amplifier.So let's solder all the Parts to a PCB. I made this layout for the board to make things easier.And While I'm doing this, let me tell you that this is a pretty simple amp,Which does not feature the very best quality,And if you think that you lack the skills it needs to build your own amp, you can always buy a premade kit.I put a link in the description, or you want to go super efficient, and want to build a class D amp.Then check out Afrotechmods tutorial about those. Now the amp is done but as always I forgot something.The Bluetooth module of course! I open its case very carefully, and immediately saw where to hook up the power.So I added an LM7805 voltage regulator to the circuit,Which powers the receiver,But there's just a small problem. When this receiver shares the same power line, it produces distortation for our amp,And this is something you can clearly hear and do not want. And while I tried to fix the problem,I destroyed my receiver.Because i'm such a genius.So I bought a new one, and I'm just going to use an external 5-Volt power supply, this way it'll work fine.I use this great project box to secure my electronics inside, and drilled two holes for the speaker wiresAnd power wires.And one extra hole for the audio cable. I slid the speaker wires into the case and soldered the black one to ground,And the red one to the negative side of the biggest cap. I did the same thing for the power wires.The brown 12-Volt wire connects to the upper terminal, and the blue ground wire connects to the other terminal.The audio cable is the only one missing, so i cut the wire and tinned those. Black is ground and connects to...Well, ground.Left and right channel connects to those two caps, and of course I willAlso need a 12-Volt power supply. I used this Switching power supply, which can give me 2.2 amps,Even Though I only need 200, but, well, okay.Now let's head to the bathroom and I will start to determine the location of my speaker.And use this special saw to cut out this beautiful circle.When I was sure that the speaker will fit later, I went ahead and turned off the lights and also turned off the circuit breaker.Please don't forget that! 230 volts can kill you!Then I used two terminals to get some power from my LED lights, and connect those to the230 volt Input of my 12-Volt power supply and my 5-Volt power supply.Now I put all the components into the ceiling and secured my speaker with screws.And from now on, I can enjoy the awesome sound of my speaker inside my bathroom, and so can you if you build this too!If you liked this project, why not give it a thumbs up?Be sure to check out my other videos and subscribe to stay up to date With my channel .Stay creative, and I will see you next Time!