Production work....

Ok well seven boards might not be full on production but for me its the largest (in pieces) order that I have had so far. Everything passed the smoke test but I still need to make sure functionally they work.

I shipped out the large MP3 board to the customer last week. Waiting to hear back to see if they like it etc. Hopefully I will hear something soon.

Touchy Touchy

Once I got the audio portion figured out I needed to make sure that communication to the LCD worked. Well it works....kind of. I had to solder on a jumper wire for my board to receive data from the screen.

I can now detect that the screen was touched but need to work on the code to actually get positional data. After that I'll be working on the UI layout for the client.

After this project is done I think I might build be an integrated amp using this touchscreen and the amp. Should be fun!

Version Two Works!!!!!

It has been a really busy last few months. The wife and I bought a house and we had a baby. It took me a couple months but I redid the MP3 board and ended up creating a large amplifier shield. I finally had a chance to work on the code and the track selection buttons work as they should. I need to fine tune some timing issues but the bulk of the work is done. 

By still having a regular Arduino on there it gives me the option to add shields for later. Now to ship it off to the customers and see what they think.

 

MP3 Board Testing

I got one board assembled and working on testing it. The mic portion works as it did on the mic boards and the amp works well. I had to get out my 12V 6A power supply to test it. I think I will lower the gain on the mic stage, a little bit of hiss gets through.

I tried the MP3 portion and I am not getting any audio. I am working on trouble shooting that now. It seems the Arduino is working as it should. So next to check is the memory card and then the MP3 ic.

There are some modifications that I need to make to the board but nothing major.

Boards have come in!!

Its a month to the day since I last posted. Since then I have started the process on purchasing a house and found out that I have a little girl coming in November.

I ordered the boards and it seems they took a little longer than normal for what ever reason.  I can't complain though the price is right. This weekend I will building one of the boards up section by section. If these audio amps turn out to sound ok I might have to make a little integrated amp for kicks. I already see some changes that I want to make to the board but that will have to wait till the next run.

The smaller boards are just more mic mixer boards. 

They look good, crossing my fingers that they work.

Finally Done!!

I have been working on this for a client for a while and its finally done. I still need to order some prototype PCB boards to make sure that everything is ok. There are also some V2 changes that I want to do already but they are things for ease of assembly.

I am using the VLSI VS-1053 audio IC to do the decoding of the mp3 files that are going to used. For the software I'm using Bill Porters library for the IC. ( http://www.billporter.info/ ) This is the same MP3 IC that can be used on the Sparkfun MP3 Sheild.

If these audio amp ICs work out well I might have to use them for some other projects. 43W into 4ohms each is the making of a nice little integrated amp for the desk.

Here's the layout for the board, I'll report back if it works as it should or not.

Mixing things up

I was hoping to be able to do one post a week, so far that isn't happening. Works been crazy busy but I love what I do so I am more than happy to do it.

Anyway....

I am working on a side project and thought this would make a good how to. Most of the electronics projects that I do are focused on audio and this one is no different. This is a small three channel mixer going made with a LM368 amplifier. (data sheet: http://www.ti.com/lit/ds/symlink/lm386.pdf )

This particular setup is to mix three microphones (the cheap kind you get at radio shack etc) into one output. This output can drive a small speaker or be used as a source to some other device.

Starting with the stereo jacks ( I didn't feel like looking for mono ones in Eagle), the signal goes into a pot that is used for adjusting the level of the incoming signal. The cap (C49,C56,C50) is there to block any DC coming from the source.

As its used here the LM386 has a gain of 200, if you get rid of C46 and C48 the gain will end up being 20. With the lower gain it would be more suited for higher level signal devices like an MP3 player.

The 250uf cap (C47) is there to block the output DC coming from the LM386 since it is biased at 1/2 of Vin on the output. DC on the audio signal path is usually a bad thing.

If you get creative you could set this up as a stereo mixer. You would just need to copy the everything after the jack and use the  right channel on the other side. This could also make a very useful portable headphone amp.

That is pretty much it, not much to it really. The setup here for the LM386 is taken straight from the data sheet as a reference design. There are some others included as well.  If you have any questions please ask or if you would like to see something else let me know.

 (be careful though, you do not want to over drive the what ever you are using after this....you have been warned and I take no responsibility if you let the magic smoke out).

DIY CD Player Power Supplies

I have finished all three mixer boards and they are ready to ship. I was finally able to get some time to work on my on going (three years now) DIY CD player. I tried etching these power supply boards my self and they turned out OK but I wanted them to look good.

These were the first two boards I had done by an outside company and I made some mistakes. Putting text on the copper layer being the biggest issue.

These are simple linear regulated power supplies, nothing special at all. 7805, 7905, etc. There are some parts missing, that's due to missing hardware for the heatsinks. There is also a resistor missing for an LED that I have.

I have the new DAC board mostly done so hopefully I will have that posted and working. Now I just need to hook up some AC and make sure these things work.

Mic Mixer, Take Two

I was having some weird volume control issues and realized I messed a couple things up. Made the corrections and the new boards arrived today. Glad to say everything works beautifully now.

I am working on an MP3/mic mixer/power amp board for the same client that will include this whole design in it. I am almost finished with doing the board layout. Once that is done its just a matter of ordering parts and making sure that I have everything connected properly.

I will try to do weekly posts. They should be a little easier to do since things are rolling on the contract design side as well as the personal project side. I will be ordering some heatsinks for the CD Player power supplies and will be testing those soon. Check back for updates.

My dark little corner

I figured I would start a blog, if for nothing else to help me keep track of information on my projects. After a year of being in a new place I finally have a proper work space setup. I have room enough to have a couple of projects on the bench at a time.

Here is a picture of my work space. Gotta love surplus Govt stuff from the local bases.

I am currently working on a project for a friend of mine as well as my own. Here is a little mic/mp3 mixer board that I am putting together. I messed up the board so the headphone jacks won't fit. I will have to reorder them, but before I do I want to test it and make sure it works.  I need to order some new pots for it as well. The ones that I received are turned 90 degrees and its impossible to get to them.

Make sure to come back often to see what else I might be brewing up, hopefully its something good.