Saturday, 16 March 2013

Harrymatic Stutter Distortion

Request. This one comes from Harrymatic's instructables.com project. Check out the page for more information and demo clip with keyboard. This one has really low part count, but tons of links keep the board pretty big...


15 comments:

  1. I think one could have a lot of fun with this one
    Might box it up with an autowah

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  2. Hey Miro, I'm not sure this one is correct, I've made it up but there's no power going to the LM386 in one of the switch positions. I noticed on the original schematic Harrymatic uses a DPDT to be able to have power going to pin 6 in both positions and the switch is just to turn the power to the 555 off, maybe it would be better to take a 9v feed straight to pin 6 of the 386 and use an SPST, that way you could save a row. Also I think there's a missing cut between pin 6 of the 555 and pin 2 of the 386, they're not linked on the schematic. And possibly the link between SW1 and pin 3 of the 555 should go from SW2 to pin 3, oh and Vol 1 and 3 need swapping (this is the only thing I can say for definite). Sorry if some of this isn't correct, I didn't have much time to debug it before I had to go pick my girlfriend up from a night out and now it's too late to start picking up the soldering iron again :(

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    1. You're right about the cut and about the volume pot labels. Thanks. Those i'll fix right away... But for the switching - you can't take the 9V straight to 386 pin 6 as the other position has it connected only to 555 pin 3. I'll just redraw the switch part for DPDT to match the schem.... I'll post the corrections in a bit.

      I just love drawing layouts on the evenings with a slight hangover.. Only bad thing in that is that i seem to get a lot more error prone :)

      +m

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    2. Updated and shave off one column and one row. Jigged a few links around too to make it prettier. Hope this one works out... :)
      +m

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    3. Cool, thanks man. The only reason I thought putting 9v to the 386 would work was because it looked like using the dpdt switch gave 9v out to pin 6 no matter what position it was in because of the way it was wired, thanks again anyway, time for round two with this thing :D

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  3. Ok, I've been out all afternoon but I've had another play with this now. I'm afraid the current wiring on the dpdt switch doesn't work correctly, it doesn't pass signal (I'm guessing power) in the distortion only setting, I've rewired the switch using the pinout from the instructible and it works great, well great may be an overstatement. It's got quite a loud clock noise mixed in with the signal in time with the stutter effect, I know Harry states this in the article but I was thinking maybe there should be a way to reduce this, maybe with a pulldown resistor similar to reducing pop with a stomp switch? Oh and it looks like the rate dial should use pins 3 and 2 rather than 1 and 2 as it's working back to front at the moment. It's quite a nice idea as an effect, if the clock noise/pop can be sorted it'd sound great, also there's scope for improving the LM386 side of the circuit, maybe use something based on the Lovepedal Purple Plexi, though the setup Harry has used sounds good.

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    1. Don't know how to reduce the noise.. This is pretty crude way of creating tremolo - cutting the power from driver IC with a clock :)

      I'll revisit the switch with Harry's layout, rather than the schematic..
      +m

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    2. To be honest it's more of a gate than a tremolo so it gives a really cool effect. I'm going to dig a bit deeper with this because it's definitely got potential. At the moment it's more like a proof of concept than a genuinely usable circuit.

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    3. I interpreted that as an tremolo - Harry states that it is a Distortion with a Stutter effect :) And that's true.

      I relabeled the switch according to Harry's layout, so i *think* it should be ok now..

      If you come up with a solution to clean the interferences, please let us know. I'd be happy to post a more guitar friendly, modded version of the layout.
      +m

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    4. Will do, I definitely want to get this sorted as it's great apart from the noise. I think it'd work well with a momentary foot switch in place of the dpdt too.

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    5. By the way.. Does your switch wiring match the current one on the layout? If it does, i think that means verified...
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    6. It's almost the same but I've got 9v going to lugs 1 and 4 with 6 free rather than 1 and 6 with 4 free. Everything else is the same though.

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    7. So you have it flipped vertically. It should be the same then. Shall i tag this one with a note that we may see a better working Madferret mod layout in the future? :)
      +m

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    8. I've read a few forum posts about needing decoupling caps to get rid of the 'crowbar effect' which seems to be what I'm hearing. It looks like the bottom 10uf cap may need increasing to 47 or even 100 and another one needs to go from row one to ground which should provide a decoupling cap for the 9v source going to pins 4 and 8. I'll let you know if that works.

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    9. Byt the way Madferret: Just for reference in other ways to create crude tremolos - check out Dragonfly's "Whirlygig". I noticed the same effect when i was on the breadboard stage of the Trixie/Fancy fuzz development. I'm planning on drawing that Whirlygig at some point too...
      +m

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