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1  Using Arduino / Audio / Re: Real time MIDI w/ music shield on: March 18, 2014, 03:41:08 pm
Ok I figured it out. MIDI works just fine...
Musicplayer.cpp (from Music_shield library) has function midiDemoPlayer() which can play notes, change banks, etc.
It was just a matter of moving midi functions from private to public in MusicPlayer.h file and then calling them from your sketch...
For example:
Code:
player.beginInMidiFmt();
player.midiWriteData(0xB0, 0x07, 120); // Set MIDI channel volume
player.midiWriteData(0xB0, 0, 0x00);  // Select bank GM1
player.midiWriteData(0xC0, 1, 0); // Select instrument (Piano)
player.midiNoteOn(0, 70, 127); // Play note (C4)
delay (1000);
player.midiNoteOff(0, 70, 127); // Stop playing note

2  Using Arduino / Audio / Real time MIDI w/ music shield on: March 18, 2014, 07:07:36 am
Has anyone had any luck of getting real time MIDI to work with seedstudio music shield v1?  It's based on VC1053B.
3  Using Arduino / General Electronics / Re: Indirect touch sensor on: March 04, 2014, 01:15:48 pm
Yep. I'm just playing with capacitive sensors and a jam jar lid on the end of a wire can easily detect my hand from 10cm away.

(that's about 4 inches in old money)


Wow thanks!
BTW Just found this tutorial on the subject http://playground.arduino.cc//Main/CapacitiveSensor
4  Using Arduino / General Electronics / Re: Indirect touch sensor on: March 04, 2014, 10:45:08 am
Capacitive sensors can do it.
Other than that, buttons can too be behind a piece of plastic.
Thanks! Buttons are out of the question, it's a rigid plastic in old fashion telephone handset.
5  Using Arduino / General Electronics / Indirect touch sensor on: March 04, 2014, 10:36:39 am
Does anyone know if there's a sensor in existence that can detect human touch behind solid piece of plastic (no direct contact with sensor)?
6  Using Arduino / General Electronics / Re: Is 4n33 optocoupler fast enough for MIDI? on: February 21, 2014, 04:26:01 pm
Perfect! Thanks a lot LarryD!
7  Using Arduino / General Electronics / Is 4n33 optocoupler fast enough for MIDI? on: February 21, 2014, 03:52:52 pm
I'm building Arduino based MIDI controller (this is my first MIDI project, initial planning phase).
To isolate synth I want to use optocoupler.
I have some 4n33 optocouplers already, would they be fast enough to send serial data to MIDI port? From datasheet turn-on time is 10uS and off is 100uS. I know that MIDI baud rate is 31250. Should it work?
8  Using Arduino / Audio / Re: Sound gets distored when going thru digital pot on: January 29, 2014, 04:26:24 pm
Ooh, wish you had an oscilloscope so we could see what was happening on the pop.
Gotta be the part going open circuit or closed circuit internally as it switches, something like that.

I have one actually, been using it to monitor sine wave while tweaking resistor values in this circuit... I'll see what I can detect with it..
9  Using Arduino / Audio / Re: Sound gets distored when going thru digital pot on: January 29, 2014, 03:35:40 pm
Thanks guys! Got it working with help from you and guys at DIYAudio forums.
I also had to add (R5,R7) 47K resistors (towards ground) otherwise a little sound would bleed thru.   And R8/R9 100K resistor to bleed charge out of C3/C4 so it doesn't kill my speaker.
Learned how to use LT Spice emulator in the process, very useful!
But by solving one issue I created another one. Now every time I change volume I hear loud pop (higher volume, louder the pop). I read that it's problem with generic digital pots smiley-sad   It looks like I might have to switch to PGA2310 or something similar designed for audio...

10  Using Arduino / Audio / Re: Sound gets distored when going thru digital pot on: January 27, 2014, 08:45:56 pm
Yeah decoupling C5 is not polarized... I'm confused about polarized tho. I see I have C1 and C2 incorrect, current flows from R/L-in to the IC, but not sure about C3, C4...
11  Using Arduino / Audio / Re: Sound gets distored when going thru digital pot on: January 27, 2014, 08:28:07 pm
C2-R6-R7 not wired correctly.
Polarity of C3/C4 are not wired the same.

Ahhh my bad!
How about now? smiley
12  Using Arduino / Audio / Re: Sound gets distored when going thru digital pot on: January 27, 2014, 08:18:54 pm
Does this look right? smiley
13  Using Arduino / Audio / Re: Sound gets distored when going thru digital pot on: January 27, 2014, 10:33:37 am
Yes, feed the signal thru a capacitor, to the junction of two 100K resistors between 5V and GND, so the junction sits at 2.5V going into the pot.
Then feed the pot output thru a cap again to the amplifier.
Awesome! So this is whats called bias offset right?  Do I need voltage divider on the output as well or just the cap?  Would 10uF cap be ok?
14  Using Arduino / Audio / Re: Sound gets distored when going thru digital pot on: January 27, 2014, 10:23:20 am
To fix it, you'll have to offset the input signals.  Depending on how your amplifier is coupled, you might have to shift the output signals back to bipolar.
Thank you so much!  But how do I offset input signal? Add a voltage divider?
15  Using Arduino / Audio / Sound gets distored when going thru digital pot on: January 25, 2014, 04:39:23 pm
I've build remote volume control box that changes volume of the line signal passing thru it with help of MCP4241 10K digital pot. Everything seems great when source of audio was my TiVo, however when I connected Xbox 360 I noticed that something is very wrong with sound. Anything that has bass in it sounds very distorted (like speakers were ripped)... This especially clear during explosions...  Is this the nature of digital pots or I'm doing something wrong?  Can I add some components before or after pot to  fix this issue?
I'm attaching schematic, but it's pretty basic...

Edit: I think this is clipping smiley-sad
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