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Newbie question about pedal build

Discussion in 'Effects [BG]' started by Bass4lyf, Apr 26, 2010.


  1. Bass4lyf

    Bass4lyf

    Nov 1, 2008
    Sydney
    Ive got a big project coming up soon and thought Id do a simple compressor pedal build just to sorta get my head in the right place so I dont muck up the big project. Anyway, I did some shopping and have all the parts needed for the pedal build. This is probably a really stupid question but, can resistors, capicitors, transistors and diodes be soldered into the circuit back to front? Or can they be put in anyway? Are they directional?

    Thanks
     
  2. BruceBass3901

    BruceBass3901

    Oct 17, 2009
    Wickham, UK
    Most resistors are not biased, so can be put in any way round. The bias of diodes, transistors and capacitors is very important. Maybe post a pic of the components you are unsure of?
     
  3. Bass4lyf

    Bass4lyf

    Nov 1, 2008
    Sydney
    ok cool. Another question. This is what Im doing - http://www.tonepad.com/getFile.asp?id=11

    Schematic should be on that page or off a link on that page.

    There is a small arrow running along the wire pointing to a line coming off the wire, then theres another bigger arrow coming off that line that comes off the main wire. Its on the bottom left area of the schematic, above the 2k4 resistor. What is this? There is another similar thing to this abit to the right of it under the .0022 capacitor.

    Ive been stuck on this for ages going through numerous schematic symbol websites, cant find anything. Help will be greatly appreciated!

    EDIT: I have just found that this is a transistor. Which end is the emitter, collecter and base? (Its a 2n 5484)
     
  4. Do you have a multimeter? You can check with that.

    To be honest though, your best bet is to just follow the layout diagram. It shows you the rotation of Q1. Notice the flat edge?
     
  5. Silent Fly

    Silent Fly Supporting Member Commercial User

    May 8, 2006
    London - UK
    Owner/designer [sfx]
    As you pointed out it is a transistor.

    Not all transistors have emitter, collector and base - only BJT transistors. The transistor in the schematic is a jFET.

    Regarding the 2N5484 (in the schematics is 2N5457) I would suggest you google it. You will find the datasheet that tells you everything you need to know about that specific transistor.

    More in general, I would recommend you read a basic book about electronics before you start any project. I’m sure your local public library has more than one available.
     
  6. Bass4lyf

    Bass4lyf

    Nov 1, 2008
    Sydney
    ok cool. Yea im reading "Inside Tube Amps" by Dan Torres. Great book. Still learning though as you can tell. Yea sorry I just found it has D, S and G. D - Drain, S- Source, G - Ground. Is that right?
     
  7. Silent Fly

    Silent Fly Supporting Member Commercial User

    May 8, 2006
    London - UK
    Owner/designer [sfx]
    No, it isn't :)

    Have a look here - "Structure" section.
     
  8. Bass4lyf

    Bass4lyf

    Nov 1, 2008
    Sydney
    With all the grounds in the circuit, do they attatch to the pedal chassis or do they connect up to the ground on the input jack?
     
  9. The key is that all grounds should connected together. The ground of the jacks is a fine place, as metal jacks on a metal chassis will also ground the chassis (watch when you put the back cover on that you don't short any components to the cover - trim those leads after they're soldered)
     
  10. Bass4lyf

    Bass4lyf

    Nov 1, 2008
    Sydney
    alright sweet. Also, with that transistor, above the 2k4 resistor, on the schematic, the symbol of the transistor has an arrow that points up, but doesnt connect to anything. Why is that? Is it meant to be left unused?
     
  11. I'm not sure without seeing it but a resistor with another line through it is generally the symbol for variable resistor - a pot (a knob).
     
  12. Bass4lyf

    Bass4lyf

    Nov 1, 2008
    Sydney
    nah its not a pot, there is two transistors on the schematic. The transistor on the left has three prongs or wires. On the schematic, only two of those prongs/wires are connected. The prong on the left (looking at the flat side) is just an arrow that points up, doesnt look like it connects to anything. Ive attatched a link to the schematic above.
     
  13. faceinbass

    faceinbass

    Apr 20, 2008
    KCMO
    the only arrow that points up is a wire, to the middle lug on the pot.

    the trannys have three legs and there are solder points for each. :meh:
     
  14. Taylor Livingston

    Taylor Livingston Supporting Member Commercial User

    Dec 25, 2002
    Oregon, US
    Owner, Iron Ether Electronics
    The upward arrow means it is connected to the positive power rail (+9v in this case).

    You should start here:

    http://www.diystompboxes.com/wiki/index.php?title=DIY_FAQ

    Then go here:

    http://www.geofex.com/effxfaq/fxfaq.htm

    And when you've read those each 5 times and you still have an unanswered question, ask here:

    http://www.diystompboxes.com/smfforum/index.php
     
  15. Bass4lyf

    Bass4lyf

    Nov 1, 2008
    Sydney
    alright sweet. Everything is wired up, works in bypass, no bad noise, just clean dry bass signal, but when active, the signal becomes very significantly quieter, and the signal does drop out into absolutely no noise whatsoever randomly (except if you play the string really hard, you get abit of signal that has very slow attack and almost has a fart sound), every 10 seconds or 30 seconds or so and then the quiet signal does come back and so on. Im guessing there is a fault in the circuit then as it does the same thing when I take the footswitch out. What could be the problem?

    I have checked for short circuits, I have gone over my layout of the components in accordance to the schematic millions of times, I have eliminated every problem I have found and I have no clue. I do have a multimeter and have abit of an idea on how to use it, is there any tests I can do with the multimeter to find the problem in the circuit?

    Btw, thanks for the links everyone, I am also spending hours researching and trying to find out the problem for myself but aint too successful atm hence why im posting on here.
     
  16. Taylor Livingston

    Taylor Livingston Supporting Member Commercial User

    Dec 25, 2002
    Oregon, US
    Owner, Iron Ether Electronics
  17. Bass4lyf

    Bass4lyf

    Nov 1, 2008
    Sydney
    I whipped out my multimeter, put the black on the grounded part of the circuit board, and red on the op amp. This is what I got.
    9v battery=8.7

    op amp-
    1=8
    2=7.6
    3=7.5
    4=8
    5=7.5
    6=7.5
    7=8.1
    8=8.6

    Is that enough or do I need to do the same for every component? I tried measuring everything on the board with black on ground, about half of the capacitors, resistors, one transistor and the diode show 4-8 v, whereas the others show 0 v. Is this normal?
     
  18. chicago_mike

    chicago_mike

    Oct 9, 2007
    Chicago - LA - Rome
    Endorsing Artist : Genz Benz
    Check your ground. And your Vref. Vref should be about half of your supply voltage. There should be no voltage to ground. Band on the diode correlates to the line on the diode symbol. The curved line on the caps correlate(sp) to the negative end of an electrolytic or a tantalum cap.

    The 2 2N5457's ( 2N5458 and 2N5459 ) flat side facing the sun (up), is Drain Source Gate. To replace this you need to know the Gate-Sourve voltage and the Drain Gate Voltage. You can use in there a 2SK117, 2SK170( these are Mosfets) and the J201. Pay attention to the pinout though.

    Double check your spldering and clean the board with isopropil alcohol, the highest percentage you can buy. Dont get the 70% stuff that will leave impurities on the pcb and cause you to have bridges and shorts and other nasties.

    Fets are finiky, you may have fried them..doubtful but it happens.
     
  19. Build an audio probe. Instructions will be in one of the thinks Conical posted.
    You can trace the audio signal though the circuit and find where it starts playing up eg: if the signal is going into but not out of a transistor it probably has the wrong polarity.

    What schem are you using. I found this one but is different to yours...

    orgsqz.

    In this schematic you can check to see if the signal is going in to pin 3. If there's nothing coming out pin 1 then its possible you've got your IC in the wrong way. *check that!* (1 is where the dot is. if there's no dot then the little notch is the 'top' - 1 is on the left.) Are you using a socket for your chip? If it's in wrong then the voltage would probably have fried it - you'll need to get a fresh one.
     
  20. chicago_mike

    chicago_mike

    Oct 9, 2007
    Chicago - LA - Rome
    Endorsing Artist : Genz Benz
    He's building the tonepad wich has two n channel fets.
     

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