SEQUENCE DRUMS casio sa series... GATED STEPS??

[Steve DrGwon]

HI GUYS!! Im trying to build a sequencer for triggering the drums of a casio sa2. As a lot of you already know a tipical 4051 sequencer its not the right sequencer for this mission. its not possible to trigger the same sound in sucessives steps.,because it need to have a "cut" between itch step...    After spend hours searching on Google I Found,,,NOTHIN helpfull.
The easiest way of solving this problem is to use a 16 TO 1 multiplexer and build with it a 8 step sequencer using 1,3,5,7,9,11,13,15 outs,,that way you have the "cut" you need between steps,,, BUT I WONDER(im pretty sure there is a much better way of having this "Cut")IF THERE IS A WAY OF DOING IT USING A 8 TO 1 MULTIPLEXER so its no necessary spend my 16 to 1 MUX??.

I guest my question is.. IS THERE A WAY OF "CUTTING" THE STEPS OF A MULTIPLEXER SEQUENCER??

I hope someone can help a silly newbie
THANX IN ADVANCE

[Steve DrGwon]

Hi GUYS! Finally I see light at the end of the tunnel.. Didn't have the CHIP to try it yet but looks like a good solution for the Casio SA Sequencer I'm trying to build.  It use a 4081 AND gate... One input comes from the sequencer channel and the other one from the clock oscillator..then you have this "cut" in the signal I was trying to optain...
Its my first time using a 4081 and I'm not sure how it works... For what I read it have 2 input a 1 output ..then you apply voltage to the input. This voltage can be high or low..if its high in booth input the gate its "open" in any other combination the gate its close.. Am I right?
I saw there is a way of doing this kind of gate with 2 transistors.. I think I will have a go trying with the transistors before a order the 4081.
I will try to Integrate it to my circuit ...I hope it works!
Catch you later Guys!!

[Steve DrGwon]

Hi GUYS!!I order the IC 4081 AND gate ,,,unfortunately i gonna have to wait alot,,,,SO i build a simple AND gate with 2 2n3904 transistor, it work! but something happens when i add it to the sequencer circuit, i only build the AND gate in one of the sequencer´s steps.. the sequencer run great until it arrive to the step with the AND gate, then it STOP... only restart when i unplug the clock from the AND gate.

    i suppose something about invert current it is involve. I try add a diode between clock and the AND gate but makes no difference.

   I use a 40106 to generate the clock signal, a 4040 to convert this signal into binary, with this binary signals i control a 4051 multiplexer that its the steps controller,

you can check this video if you are interested on it, https://youtu.be/t7JYOIYqMEY (circuit schematics link on the video description)

In my opinion its a great sequencer design cause with a few switches or pusher you can change steps order... ALOT OF FUN!!


Basically i use the same circuit to which i add this AND gate at the multiplexer outputs (and LEDs to ground throug 1K resistor).

Well not a big progress,, I´m gonna have to struggle a little more.

      ANY SUGGESTION WILL BE VERY APRECIATED!! XD

Catch you later guys!!

[Steve DrGwon]

LOGBOOK october 25th 2018

    Its been a long time without human contact,the resistors seen to be hostile,,, i refuse to have any more conversation with they.I think im gonna start negociations with the other big tribe..the capacitors,,, Im afraid the diodes attack the vessel while i sleep. I still have hope in this mission,,,The sequencer is real!!! I'm going to find it even if it's the last thing I do in this misery life OH LORD HAVE SOME MERCY OF MY SOUL!!


  HI GUYS!!
   I make a little progress, but still a few things i have to fix.
   i attach a "beautiful" drawning of the circuit.
  1-The sequencer seems to work almost well but when I raise the clock the LED that indicates the tempo of the clock stops flashing... I'm not sure what's going on there. Something to do with the inverter maybe (The first transistor after the clock output)?
     The output of the sequencer if i conected to a LED seems to work fine.., but when I connect the PINS of the Casio to the last transistor (the one with red resistances in the schematic)does not seem to work right.. At least doesn not sound any drums from the Casio,,,i try to add a couple of resistances(i play with diferents values... 47k 100k not lower than that cause im afraid of burning the casio chip with to many voltaje.. IS THIS POSSIBLE??) between the emitter and the connector and the ground and 9v + respectively(red resistances in the schematic)...
That way sometimes it works but only a couple of times then stops  working completely or  trigger sounds  "ramdomly " (I'm not sure that is said that way in English XD sorry XD)

  SO THATS MY HISTORY,,, i HOPE SOMEONE CAN SHARE SOME KNOWLEDGE WITH THIS ROOKIE


THANX!!