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31  Using Arduino / General Electronics / Re: Simple (I think) problem with very basic drum machine trigger on: March 07, 2013, 06:53:22 pm
Could we talk you into replacing the whole circuit with an Arduino ?  smiley-evil
hehehe... I'm trying to simplify things to make it small. I was planning to do it more complicated later after I finish this one.

Forget the diodes and put another buffer between the base trigger and the input circuit.
I am very amateur at this... Do you mean to double negate the output of the bass trigger? I should point out that at this point it does work as intended when the rhythm switch is connected into one of the counter outputs, but maybe it can be damaged if left for a long time?

If you need that manual trigger then turn that buffer into a logic gate. The type will depend on the normal state of the output of the 74LS93. If it is normally low then an OR gate should do. You should connect the input of the OR gate through a potential divider to get a safe input level to the gate. You should not feed over the supply voltage into a gate.
I really don't know what is the normal state of the 74LS93 counter is, the 555 timer is always running. I am sorry but got lost here, what OR gate? I know what it is, but there is none here... I think.

Thank you again for answering, it's not the first time you help me, Grumpy_Mike.
32  Using Arduino / General Electronics / Simple (I think) problem with very basic drum machine trigger on: March 07, 2013, 03:31:40 pm
Okey, I originally posted this on because it has nothing to do with Arduino, but as I couldn't solve it there and I think that Arduino forum has a lot more activity than the other one, and also there is a lot of people here that knows this stuff very well and helped me in the past. So I tried posting it here.

Thank you very much for taking the time to read this and help me!

I designed this circuit which I think is a pulse generator, made with a 555 IC, counter and an inverter to generate a ryhtm for the drum machine
Out of the picture (down) is a hi-hat circuit.

(those two things drew on the right by hand are buttons)
First of all this part is working fine, it generates a desired pulse and is having no problems by itself, also the hi-hat works fine in rhythm.

I also made two PCBs for this circuit:
which generate the snare and bass sounds and connected each one (bass and snare triggers) to the designed pins on the right of the first image. That also works fine by itself with the rhythm.

As I also want the drum and snare to be triggered by a button when the snare and bass rhyhtm is disabled (by disconnecting the switch on the right of the first image, next to the snare and bass rhythm output pins, labeled "X2_RITMO(OPC)") so I also connected a button to +9v and the other pin of the button to each trigger and THATS WHERE THE PROBLEM IS.

When I press the bass button it first triggers a bass drum sound, but when I realease it it makes a snare drum sound, also it seems that the snare button doesn't trigger the snare at all.

On the other forum a user kindly suggested I should put a diode in the bass wire, so that none of its switch action gets back to node 3.

So I made this modification:
but now it behaves in a weird fashion, when I press the bass button it makes the snare sound like a machine gun firing it very rapidly.

Any ideas what I could try? Thanks a lot!!!
33  Using Arduino / LEDs and Multiplexing / Re: CD4051 Multiplexor input test sketch on: October 31, 2012, 05:58:44 pm
Yes, I know it's not efficient but it's just for testing a connection to a MUX, works for me.
2. You may spuriously select two wrong channels before settling on  your target channel.
Sorry but I don't understand, what do you mean with this?
34  Using Arduino / General Electronics / Re: Soldering leads to arduino to finish up? on: October 31, 2012, 05:57:14 pm
today I removed the female plastic for the pins and after getting something as the Diavolino as fungus is showing us then I soldered the cables directly to it
I think that is better than gluing them
35  Using Arduino / General Electronics / Re: Audio out and speaker on: October 29, 2012, 12:24:02 pm
Hey, thank you very much to all for the great help and the time!
I think I got it now, the jack will act as a jumper when a plug is connected, that goes in series to the speaker.

I'll buy some from ebay!
36  Using Arduino / General Electronics / Re: Audio out and speaker on: October 28, 2012, 07:21:57 pm
ok, yes, but where do I connect the switch output of the jack?
37  Using Arduino / General Electronics / Re: Audio out and speaker on: October 28, 2012, 01:12:44 pm
ok, and where the switch of the audio jack goes connected on that schematic? If it were a normal switch I would think that the switch goes from R7 to speaker, but I have no idea how to do it with a built in switch as it has only one connector.

also, I dont see R7 value and what value should be correct for the R9 potentiometer?
38  Using Arduino / General Electronics / Re: Audio out and speaker on: October 28, 2012, 12:11:47 pm
Oh... so when I connect the line out the speaker gets automatically disconnected? That is awesome.
And R9 is the volume, right?

39  Using Arduino / General Electronics / Audio out and speaker on: October 27, 2012, 03:38:49 pm
I am working on some sort of synth and want to add a speaker output but also a line out, and if I am using line out the speaker should be deactivated.
I was thinking that I can use this amplifier: and have a switch on the OUT after the Master volume so it can switch between speaker and line out
Will that work ok? with no noise or problem at all?
40  Using Arduino / General Electronics / Re: Weird led behavior? on: October 22, 2012, 04:28:53 pm
Thanks for answering!
yes I did it like the picture, now I see what you mean, as the leds were not polarized (I mean they turned on on whatever orientation) once one shift register output becomes high it will get trough the led and as the other outputs of the SR are on low it will make the other leds turn on (on inversed polarity)... so that is what happened.

Now that I changed the leds to polarized ones it works perfect!
41  Using Arduino / General Electronics / Weird led behavior? on: October 21, 2012, 10:00:59 am
I have made a PCB for the circuit I have attached. Those 12 leds on the left are sharing one resistor because only one of them will turn on at a given time, on those leds I put some I had stored, they don't seem to have a cathode and annode, the orientation work the same and the 2 legs are equally length. What they did is some of the voltage seems that was going trough the leds into GND.
I really don't know a lot of ellectronics so really can't explain it very well, but when connecting the PIN13 of arduino to the GND terminal of the leds, if one of them was turned on, I could get a "1", and so some of the other leds got turned on as well. After replacing those leds with normal ones it did work as intended.

Could someone explain why I got a "1" on the GND terminal after the leds? Of course if I connected PIN13 after that shared resistance I got a "0".
42  Using Arduino / General Electronics / Re: Help with drum machine schematic on: October 16, 2012, 08:24:26 pm
oh, so can I take the 5V from the arduino board and maybe put a resistor somewhere in there in order to get the voltage down to 4,5V... or something like that?  smiley-razz
Sorry, I am a begginer about circuits.
43  Using Arduino / General Electronics / Re: Soldering leads to arduino to finish up? on: October 16, 2012, 12:29:24 pm
I get strips of male pin headers.  You can get long strips and snap off sets of the desired size.  I then plug the male pins into the female sockets on the Arduino board and solder to the part of the pin that would normally be soldered into a circuit board

Sorry, I don't understand you mean a pin header like this, right?
How do you solder that to the inside of the Arduino female pin? it has plastic all around!
44  Using Arduino / General Electronics / Help with drum machine schematic on: October 16, 2012, 12:21:13 pm
Hi, I saw this webpage which has the circuit for a drum machine explained:

I was wondering, once I do the circuit for a "snare drum" (SD) for example, where should the Arduino output pin be connected? To the termination where it says SD maybe?
And what type of output should it use? Just sending a digital "1" on the Arduino pin to the snare circuit make it sound?

45  Using Arduino / LEDs and Multiplexing / CD4051 Multiplexor input test sketch on: October 13, 2012, 07:07:11 pm
I made a little sketch to test my MUX shield and thought it may be useful to someone else
It's for testing INPUT potentiometers

Sorry for spanish comments, but you just need to copy, paste and change multSelPins[] to the inputs (S0,S1,S2) of the MUX and muxPin to the Pin of "COM OUT/IN" (Pin 3 of IC)

//change multSelPins[] to the inputs (S0,S1,S2) of the MUX and muxPin to the Pin of "COM OUT/IN" (Pin 3 of IC)

const int multSelPins[]={2,3,4}; //selectores del multiplex (S2,S1,S0);
const int muxPin=A5; //salida del mux

void setup() {
  pinMode (muxPin,INPUT);
  for(int x=0;x<3;x++){

void loop() {
  int channel[]={0,0,0};
  int value=analogRead(muxPin);
  int channel1[]={0,0,1};
  int channel2[]={0,1,0};
  int channel3[]={0,1,1};
  int channel4[]={1,0,0};
  int channel5[]={1,0,1};
  int channel6[]={1,1,0};
  int channel7[]={1,1,1};

void multSelectInputFun(int inputSel[]){
  //Serial.print("multInput :");
  for (int x=0;x<3;x++){
    //digitalWriteFast2(multSelPins[x],0); //prueba
    digitalWrite(multSelPins[x],inputSel[x]); //escribe el selector del multiplex con el valor que le pasamos
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