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1  Using Arduino / Project Guidance / Re: Controlling voltage out of Arduino (to replace vactrol) on: August 26, 2014, 04:47:54 pm
Thanks for the replies!

I don't think that R1 and R2 are LEDs given there names R= resistor.  They are Light Dependant Resistors (LDR).

Which make sense of the drawing's title!

Mark
Yes, sorry! I meant LDRs!


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What signals come in on the 3 inputs?
I should have explained better, I plan to use only the input on the left (lowpass) and leave the other two disconnected, I am sending an audio signal (oscillator that comes from Arduino)

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What are you trying to do?      You can get digitally controlled filters.  That might be better than trying to convert a variable analog filter to digital control.   

However, you can replace the LDRs with digital potentiometers (if you can find the correct values) and you can control the resistance with the Arduino.
I just want to have the audio filtered and control it from Arduino, I already did it with LDRs and leds that are connected to Arduino PWM pins and that works fine! But as I plan it to do some professional PCBs and vactrols are very pricey, I thought maybe that can be controlled from Arduino without using homemade vactrols.
What do you mean digitally controlled filter? I know there are filters which have CV control and maybe that would be better, but I think they require more parts and I like the sound of this one.

 
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PWM isn't a variable DC voltage.  It's a pulsed voltage.  For example, 5V PWM with a 50% duty cycle is on half of the time for an average of 2.5V.  PWM is unlikely to work in your application.
I know it's you are not directly able to do it, but it can be done (I think) with this circuit:


Well... maybe the only choices are doing it with vactrols or digital resistor (IC)
2  Using Arduino / Project Guidance / Controlling voltage out of Arduino (to replace vactrol) on: August 26, 2014, 03:26:27 pm
I have this two leds I want to replace in a circuit, I know it's possible to vary voltage from PWM, but I really don't know if this is the same as what the vactrol does in this circuit



Is it possible to connect maybe led "R1" and led "R2" pins to Arduino's PWM's pins and replace that from there?
3  Using Arduino / General Electronics / Re: Help designing a bass booster for an Arduino synth on: July 28, 2014, 09:20:42 pm
I was thinking about the potentiometer, the thing is that I don't want to have another pot in order to save space.
So, the thing I did encircled in red, isn't that the same as adding a fixed volume pot?
No, because you only have one resistor. You need two to make a voltage divider.

Ahhhh, yes, you are right!

Well, after tingling for several hours with some circuits I found online (mainly Bass Blender by Sean McLennan) I am happy with this effect.
the input goes to a low pass filter (top left) then gets boosted by two (top-right) and gets mixed with the original input.
I also recorded a bass and I think it could be a bass stompbox (or part of)
4  Using Arduino / General Electronics / Re: Help designing a bass booster for an Arduino synth on: July 27, 2014, 09:45:13 am
I was thinking about the potentiometer, the thing is that I don't want to have another pot in order to save space.
So, the thing I did encircled in red, isn't that the same as adding a fixed volume pot?
5  Using Arduino / General Electronics / Re: Help designing a bass booster for an Arduino synth on: July 26, 2014, 07:55:07 pm
Yes, I know! the thing is that I like the sound as it is, that gain of 4 of so that now has (100k and 470K) it's making it distort, if I lower the gain it sounds cleaner.
It's like on a guitar pedal you can lower the GAIN and you can lower the VOLUME, right? Well, I would like to lower the volume
6  Using Arduino / General Electronics / Re: Help designing a bass booster for an Arduino synth on: July 26, 2014, 07:21:58 pm
YES! That was it, thanks for your time.

I modified a "blender" circuit so  the RETURN op-amp is inverted and now the transition from one sound to the other sounds great!

Theres one more thing, as you can see the RETURN part has also been amplified a lot to give it more punch and also I put a capacitor there to lower the noise it makes.
The effect is very loud, I like it very distorted as it is, but would like to lower the volume a little, so I added the part circled in red to lower it, but no matter what resistor value I use, it's useless. Doesn't get lower.
Do you know how I can do this?

PD: I attached an mp3 sample, it's starts without the effect and then it gets boosted
7  Using Arduino / LEDs and Multiplexing / Re: using 4021 parallel shift register with internal pullup resistor on: July 25, 2014, 02:45:02 pm
http://media.tumblr.com/tumblr_m15ikhGfVK1qio1b3.png
haha, thanks for the answers!

The pullup resistor is so the input is at all times connected to one level or another and doesn't gets floating between values, right? I thought it could work as the bits that the register sends don't get floating also, but I guess it's not the same principle.
8  Using Arduino / LEDs and Multiplexing / using 4021 parallel shift register with internal pullup resistor on: July 25, 2014, 08:48:10 am
I need 8 buttons and thought of using a 4021 IC.
On every tutorial there's a pull up or down resistor for every button. would it be possible to just connect the buttons from 4021 to GND and instead use the arduino internal pullup on the DATA PIN?
Thanks!
9  Using Arduino / General Electronics / [SOLVED] Bass Booster effect on: July 24, 2014, 10:07:02 pm
I am programing a drum machine in Arduino with sequencer and everything and I am doing pretty well
I wanted to add some effects for it, and thought of a BASS BOOSTER so the bass drum could sound very fat and also a little distorted if the user wanted it (you can turn up the bass booster and lower the bass drum volume if it gets too loud).

I breadborded a circuit I found online:
http://circuit-diagram.hqew.net/Discrete-Bass-Booster-Circuit_4725.html


And it almost has the sound I am looking for, so it's fine for starters. As you turn P1 and P2 it goes from NO SOUND to a PUNCHY BASS SOUND.
Now, I want the user to be able to go from a DRY sound (not filtered) to a BASSIER sound (filtered and distorted) and this booster circuit only outputs the filtered sound.

It's not really what I wanted but I thought of using an op-amp as a mixer for the dry and wet output, the dry beeing always on and you can add bass by mixing the output as you turn a knob.

I then breadboarded this circuit:
http://www.experimentalistsanonymous.com/diy/Schematics/Buffers%20Switchers%20Mixers%20and%20Routers/Simple%20Mixer.pdf
and connected the dry output to one of the inputs and the wet output to another, but I am not getting both sounds at the same time, as you turn the P1 and P2 from the boost circuit it makes something strange: At one end you get full dry sound and at the other end you get the full wet sound, the weird thing is that at the middle point you get a VERY THIN sound, with no bass.

I also looked at "blender" circuits, but didn't tried yet.
What do you think???

Thanks a lot!

PD: attached an mp3 sample so you can hear it, it's a little quiet (doesn't has the bass boost!)
10  Using Arduino / General Electronics / Re: [SOLVED] Nano using 9v on Vin works weird on: August 23, 2013, 05:07:59 pm
I finished it!
Thanks again, here it is if you want to take a look at it...
http://forum.arduino.cc/index.php?topic=184158.0

I think it has quite an original sound
11  Community / Exhibition / Gallery / Auto Obstinato Synth (Arduino Mozzi + filter & fuzz) on: August 23, 2013, 05:06:58 pm
Digital synth capable of generating random sounds and melodies made with Arduino Nano and Mozzi library, sent to a LP filter and fuzz circuit.

Hope you like it!
I own a lot to the Arduino community! smiley

12  Using Arduino / General Electronics / Re: Nano using 9v on Vin works weird on: August 18, 2013, 05:00:19 pm
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No no, everything has common ground! Im using only the one on the power supply, also I'm probing on the audio output of the schematic (on the right)
Check that the wiring is actually making contact. What you describe is classic no common ground.
Sorry but there you are.
Maybe a photo of your setup?

What an idiot... I forgot to ground the audio output  smiley-red
For some reason when using USB power the audio doesn't needs a ground (when connected to the same PC I suppose)

THANKS to you all!!!!!
13  Using Arduino / General Electronics / Re: Nano using 9v on Vin works weird on: August 17, 2013, 05:58:48 pm
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How about your common grounds. Is the grounds connected when using battery, or just when using USB ?
I don't use a battery, I'm using a 200mA 9V power supply, I just connected GND to ground but I think I also tried connecting it to GND1 also.

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The 5V coming through USB is filtered.  Though the 9V should not be noisy enough to create what you are describing.

You can try adding 0.1uF and/or 4.7uF caps between Pos and Neg close to the battery.
This also applies to a power supply?

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If the regulator went to thermal shutdown, it would be off for a while.
But if there was not a common ground, it  cold produce such symptoms.
Where's the OP. Maby they have a hopping weekend, and left us till Monday.  LOL
why a thermal shutdown? It's not that the Nano goes off, it just produces a noise audio output. Also tried a blink program and it works fine with the power supply only.
Could it be that is a noise power supply? Is there a way to reduce that? Maybe with a capacitor as said above?
I'm sorry, I haven't been in the PC all this time to answer!!!  smiley-lol

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The strange thing is that when I touch the USB input of the Nano with the outside of the mini USB plug that is connected to the PC it works fine
That means you haven't got a common ground between your arduino and your audio circuits.
No no, everything has common ground! Im using only the one on the power supply, also I'm probing on the audio output of the schematic (on the right)
14  Using Arduino / General Electronics / [SOLVED] Nano using 9v on Vin works weird on: August 17, 2013, 11:50:57 am
I'm doing a little synth with a Nano and some other stuff (filter & fuzz)
When I connect it by USB it works fine and produces sound, but when I connect 9v (also tried 12v) on the Vin pin, it works but the output is faint and there is a lot of noise.
I must say that I'm probing the output after the Nano, before getting to the filter and fuzz.

The strange thing is that when I touch the USB input of the Nano with the outside of the mini USB plug that is connected to the PC it works fine, without reseting or anything, just by those two touching the noise dissapears, removing it noise comes back.

I'm attaching the schematic!

Heeeeelppp pleeeasee! Thanks!
15  Using Arduino / General Electronics / help with audio thru on: May 28, 2013, 06:35:57 pm
For a project I need to amplify the audio connected to "Input", while getting the same signal in the input to get straight to "Audio Thru".
"Audio Thru" needs to be the same signal that is going in on "Input".
And also "Input" needs to get converted from stereo to mono.

Is the connection on blue ok? Do I need to connect some resistors... somewhere??

Thanks!
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