audio -> Logic -> WTPA sync in

edited August 2009 in WTPA1 Mods
Just wanted to share a little progress with you all...

So I've got a customized 4ms Nocto Loco

to give me a logic output in addition to audio out. The pedal is based on a CD4024 counter IC.

The RCA jack on the backs of the WTPA and the Nocto are clock in/out

I'm driving the sampler's sync input with this output, and it works! So now when I play back samples I can re-pitch them based on the frequency of the audio I'm feeding into the pedal. Pretty extraordinary sounds I'm getting already. HOWEVER, audio sample rates are far too slow to make discernable samples. Is there a good strategy for multiplying clock signals? AD524? Something like that?

You'll also notice my bend wheel. Once I installed it I realized I've got a more limited range than the pot allows, so it's currently too fine of a control to be useful for anything.

And I'm happy with how the LED switches came out. Now that it looks like Todd may be designing some enclosures, I'm kind of cursing spending so much time trying to machine a cigar box with a shitty dremel!



  • May I comment on your WTPA - this is TEH SEX!

    wow! Can you comment on your led switches? Which ones did you use and how exactly do you hook these up? I was always tempted by these switches but the whole procedure of setting things up to make it work held me off. Until now... :)

    I guess your led0 is the led in the s0 switch? Basicly you just hook up the LED in the switch to the board of WTPA, right? Or is there more thinking involved?

    Thanks for the pics - really inspiring! Lets hear some of your stuff!
  • sorry - but I forgot:

    How about some gut shots of that beauty ?!
  • Sure...

    What I used were some surplus switches from Electronic Goldmine.

    HOWEVER, they came without caps. I was looking for a cheap substitute for these switches as I'm building a Bend Matrix with ~50 of these guys. The part that it calls for is $3.50 a piece. So, 5 for $1, I think I made out alright but I had to source the caps. Found a local distributor, and after some hassling them and searching through catalogues trying to find the actual part number I found the caps. the switch is a MEC TH - 3FT and the caps were 1T-16.

    I'd reccommend them, except that you'd need to buy them in bulk - Min. quantity on caps was 100 from my distributor.
    So basically these switches are just like the tact switches in the kit, but there are two more leads in between the switch leads - for the LEDs. Fortunately these switches use standard small LEDs and I was able to substitute other colors besides the stock red LEDs which you can see on sw0 and sw4, simply by tugging the LEDs out, forming my leads and sticking the new ones in. I mounted them on a piece of veroboard (Wish I had used some with copper plating), linked all of the grounds together (1/2 of the switch leads and the cathodes of the LEDs) and then connected the other side of the switches to their respective points (the upper holes on the PCB) and the other half of the LEDs to their respective points (also the upper holes).

    So yeah, my LED 0 - 4 is in switch 0-4, and then the other 3 are mounted next to the parameter knob.
  • edited August 2009
    Oh yeah, one more point -- I did have to take those linked ground points and connect them to a GND on the board -- I believe that's the lower soldered connection you can see on SW0 on the PCB

    Also, I initially wanted to make SW5 a lighted switch that would show you whether you had SW5 toggled on or off, so it would look consistent. However I opted for a simple toggle switch instead... Nice being able to "lock" effects mode on...
  • edited August 2009
    smrl - I will defintely look into the enlighted switches - You said you wished you would have used copperplated perf/pcb to mount them - for stability reasons?

    thanks a lot for sharing your approach, and elaborating on how your wtpa was done. Greatly appreciated!
  • Yeah, just because the solder creates a solid joint to the PCB that way -- Ijust bent the pins over and made solder blobs connecting point-to-point between components. It feels fine, they're not 'wobbly' at all, but I'm a little nervous about what will happen after extended sessions wailing on the buttons, etc...

    I think it would've simplified assembly a little bit too.

    One more note -- if you're going to substitute the standard red LEDs for other colors you should definitely look at the forward voltage & max current of your LEDs (different colors / varieties have different values). You may want to substitute the resistors next to the LEDs on the PCB with different values. My amber LEDs had a particularly low forward voltage.

    You can find calculators for LED resistors online if you search. Your supply voltage will be 5v.

  • Daaaaaaamn!

    Smrl, that looks AMAZING. No matter what sort of fly enclosure I might design and sell it will never ever be as distinct as what you did with a "shitty dremel". That was the point of WTPA!
    The illuminated switches look great, the toggle is a great idea for S5, and I like how you moved LEDs 5-7 up next to the parameter knob. Kickass. Absolutely great.

    I'm glad you got the sync working for you! W/r/t generating a higher frequency square wave, it's possible to do but it takes a little fiddling. You could set up an AD633 as a squaring circuit and adjust the level to be a CMOS out, and this would give you a frequency doubler (sort of -- only really for a sine wave, but close) or you could get jiggy with a PLL like the CD4046 and a flip flop or two. These are designed to multiply clocks, and they're cheap, but they are actually very complex little circuits. Or so I always thought. My buddy Peter B once swore that they sound "boring" because they do "too good" of a job of doing what they're supposed to. So maybe it's easier than I'm thinking.
    Finally, if you're handy with a compiler you could make a microcontroller (and a comparator, internal or external) do the frequency multiplication :-)

    Again, good work. That looks great.

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