Monday, 5 July 2010

Nick Greer Ghetto Stomp

39 comments:

  1. Is there a way to put the diodes on a DPDT? If so, which diode on the board would the switch connect to? Thanks

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    1. You've got a couple of choices. If you haven't made the board up yet then just leave the diodes off the board (and make it 2 columns smaller if you want) then on the switch:

      1---4
      2---5
      3---6

      Solder the pair back to back across pins 1 and 4. Take pin 2 to Volume 3, and take pin 5 to ground. The switch would be a 2 position DPDT. Or if you want to experiment put a different pair of diodes back to back across pins 3 and 6 and use a 3 position DPDT switch. Then centre off will be no diodes, and each of the other positions will bring a different set of diodes in.

      If you have already built it up, de-solder the bottom leg of both diodes and re-solder them in 2 rows above (you will need to put an additional track cut between the new diode position and the bottom of the 47K resistor. Then use a SPST 2 position switch, one lug goes to Volume 3, the other lug goes to the far right hand hole on the same row you soldered the diodes to.

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  2. Wow. Thanks for the quick and early response. Says it's 6:42 where you are. That's dedication. It's almost 10 here and I am still not focused. Thanks, I am going to start this tonight.

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    1. It was actually 14:42, Google timestamping must be a bit dodgy :o)

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  3. one more quick question, then I'll leave you be. When you say "Take pin 2 to Volume 3", is that in place of the connection to the board to Volume 3 or in addition to it? Thanks again again

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    1. In addition to it. It basically creates the link to the diodes that had previously been provided by the vero track, but with the switch in between.

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  4. Finally got it built - sans switch (couldn't get that to work) but it sounds great. It's after midnight so I can't open it up and scare the family, but I will try it tomorrow at volume. Thanks again

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  5. Hello. I have this working well - I replaced all the ceramic caps I originally had in it with mylar ones and it smoothed it out considerably. But it is still pretty dark. Not a Black Sabbath kind of dark, just not alot of treble even with the tone dimed. Is there a value to change to lighten it up just a hair? Thanks and congrats on your 100th verification. There are a lot of happy DIYers out there that you have helped. I thank you for that.

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  6. You know what? Forget what I said. The more I play this thing, the more I like it just the way it is. It's a ballsy pedal and moves a ton of air. Thanks

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    1. Sorry I missed your post somehow. Glad it's grown on you though

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  7. Can I ask what the 10n cap does in this circuit? I assumed it was for the tone control since it seems to be connected to it (and for that matter the output as well) The reason I ask is because I socketed it and have been trying other values as an experiment. I have put caps from 1p to 150p in there. The top end of the spectrum seems to give it more balls, for lack of a better term, but I wondering what it's purpose is. Thanks

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    1. The 10n and the 100K Tone pot create a low pass filter which cuts highs. So if you decrease the value of the cap, it increases the cutoff frequency, above which the frequencies are attenuated. So basically the lower the cap, the more highs will get through the filter.

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    2. Thank you. I appreciate it. That makes sense.

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  9. Just tested this one, and it's pretty good.

    Tried couple different transistors on:
    2N3904 - Boring.
    2N5088 - Not much of an change comparing to 2N3904 on this design..
    MPSA13 - This darlington is rated at 5000-10000 hfe, and it does give a lot of noise, but generally sounds just dead. No colours at all.
    MPSA14 - Darlington at 20000 hfe, not much change to MPSA13.
    2N2222 - Aww. Fuller mids and much better overall body. Even compared to 2N3904..

    You can guess that i sticked with TO-18 2N2222... :) This makes me think that it's always better to try most designs with substandard transistors. Lower hfe seems to generally give out better results..
    +m

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  10. what could i tweak to make this fatter and bassier? output cap, volume pot value?

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    1. Well the 47n and volume pot create a high pass filter, but that only starts cutting bass from around 33hz downwards and so it's already really letting all the guitar's bass frequencies through so you're probably not going to notice any difference at all by increasing that cap value. You could try increasing the 10n cap at Tone 1, or maybe make the 100n input cap larger to let more bass into the circuit. But the problem you have is that this is a pretty simple circuit with passive filters so there's only so much you can do without something more advanced to actually amplify low frequencies to give you a real bass boost.

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    2. I would try doubling all three caps. 220 for 100, 22 for 10 and 100 for 47. I would guess that then you would need higher hFE transistor (like MPSA18 or 2N5089) to keep lower frequencies from dying.
      +m

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    3. being that this is based on the electra, wouldn't it be easy to tweak for more gain?

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  11. Hi - I'm a newbie and not so familiar with electrical issues. Just a question about the schematic or layout ....
    Make it sense or/and is it usefull /or possible to bias the circuit? Just in case I will try some other type of transistors?

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  12. I used Millenium Bypass...."LED+" what to do?

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  13. The LED+ is just to connect the LED on the enclosure if you wish to. You can leave it.

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  14. Hey guys, I picked this pedal as my first build and I'm having a few issues.
    1. I wired it without the switch to try and eliminate fault points, but I'm not getting any sound, static, or anything. I double checked the board, it looks fine, so I think it's offboard.

    2. Where does the ground wire coming from the volume pot go. I feel like a total noob, but I tried hooking it up to where I have the ground wire on the output jack, board, and DC jack with no luck.

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    1. hello and welcome!
      starting from 2.
      yes ground can go to any of 2 jacks's grounds or to the dc jack ground.
      you must also ground all together:
      input's ground,output's ground,board's,pot's in this case, and dc jack's.
      if you did that, then we can go to no.1

      check again
      unwanted bridges
      orientation of transistor
      orientation of the 47uf cap
      cuts(are they clean enough?)
      and the resistor values.
      i remember myself putting in 470k in place of 470r and wondering one whole day what's wrong!
      if nothing works out, just post some pictures of both sides and we'll make it!
      hope i helped.

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    2. I was able to get some oscilation after taking everything apart and redoing the grounding and jacks and the pots make noise.

      The copper is starting to lift off of my board around the edges, so ill probably just scrap this board and try again after i build a proper test box

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    3. This comment has been removed by the author.

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    4. Not the best picture, especially since I gave up on keeping it neat after a few tries

      http://i206.photobucket.com/albums/bb137/denmorin/Mobile%20Uploads/20141129_164854.jpg

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    5. ok.
      these photos seem good to me.it's not clear on tone 2 and 3, and it seems like you've soldered your blue and black wire together in the input jack witch is wrong, but i hope you did it right and it's just a bad angle in the picture.
      i think that the problem is in your board.so 2 pictures of both sides would be very helpful for us to be able to eliminate other probable problems
      good luck


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    6. lol, found a mistake in my wiring as I was taking the picture. The wire going from volume 3 to the board was connected to where the led+ should have gone.

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    7. I'll be trying this again after I build the test box.

      here's the top
      http://i206.photobucket.com/albums/bb137/denmorin/20141129_185538.jpg

      and the bottom
      http://i206.photobucket.com/albums/bb137/denmorin/20141129_191208.jpg

      you can see in the bottom left corner where the copper broke off.

      I'm bummed that I made that mistake on the wire from volume 3, and that I'll have to scrap this due to the copper breaking, but that's why I picked an easy one to start with.

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    8. you have a mistake!
      i can't see the 47k resistor.
      but even if it's there, it's in the wrong place.from the back of your board i can see it's one hole upper than it should.it should be next to the "c" of the transistor. it seems that you've put the resistor next to the down leg of 10nf cap.
      check this please and sent back
      and clean with the a knife or razor all possible unwanted bridges cause looks like there are some...

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  15. I built this circuit this morning and it does not work I have everything ok volume knob does not work does not kill signal when its down. I hope you can help me thanks.

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    1. Post your transistor pin voltages, that will always give us the best clue and a good idea where to look for an error

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  16. Product Name : NPN Transistor;Model : 2N3904;Quantity : 100 A +/- 2% pcs
    Collector Base Voltage : 60V;Collector Emitter Voltage : 40V;Emitter Base Voltage : 6V
    Collector Current(Continuous) : 200mA;Collector Power Dissipation : 350mW;Pin Size : 14 x 0.5mm/ 0.551" x 0.019" ( L* D)

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    1. no diego.you got it wrong. we don't need the specifications of 2n3904..when mark said pin voltages, he means that you should take them from your board with a multimeter. it's done like this:
      supply 9v to the board, and set your multimeter to 20V.
      then take the COM-black cable from your multimeter to ground of the board.
      with the other cable (red) of your multimeter, you touch each leg of your transistor or ic in an other case.
      then you write down each reading that you see in the multimeter for each leg and post it here.

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  17. Built this one on Friday. I Found it to be sort of a "one-sound" circuit - it's either everything at full blast for me or it's just boring. It's bassy and has a fuzzy-drive texture with gain and volume all the way up. Tone also has to be all the way up or it's just mud. Kinda nice for slide playing, but I wouldn't waste too much time with this one.

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