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9V 2A Guitar FX Pedal Power supply

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by moody07747, Jul 5, 2006.

  1. moody07747

    moody07747 Member

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    I saw a thread at another board for guitars where someone had a pedal board adapter made up for powering all his guitar pedals.

    a few photos of the setup (link removed due to deleted old pics)


    Yea they are not the best but I asked if he could get better ones.

    I could care less about the whole clear case and blue LEDs on this one.
    I just need a good, quiet power supply that will put out 9V and up to 2A to power up to 8 guitar FX pedals.

    Now I know how to make a power supply by following sheets but I need some advice on how to keep it "Quiet" in the audio part. I can't be having that 60Hz buzz in my audio lines...I already have that problem.

    So bring on the wiring sheets and tips/tricks
     
    Last edited: Nov 24, 2006
  2. moody07747

    moody07747 Member

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    btw, i was looking at this circuit
    http://www.aaroncake.net/circuits/supply6.htm

    but that transformer may cause buzz...is there any way to do a transformerless supply?
    or would a metal box keep the buzz out of the lines?
     
  3. HiTech

    HiTech Well-Known Member

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    If you play an axe and you also dabble with electronics then this site is a MUST! You'll spend days clicking through the myriad of links and good info.

    http://www.musicianstechcentral.com/schmatic.html#misc

    The Xformer shouldn't introduce 60hz hum if you use a metal project box as well as keeping wires short and also loop a couple of turns of them through a ferrite donut or similar.
    Below are some links to what you are looking for:

    http://www.generalguitargadgets.com/pdf/ggg_reg_power_supply.pdf


    a very clean pwr. supply:
    http://www.generalguitargadgets.com/diagrams/ultra_clean_ps_sc.gif

    here is the complete page of details on the above "clean" power supply:
    http://www.generalguitargadgets.com/index.php?option=content&task=view&id=77&Itemid=106

    Of course there are many websites with similar pwr. supply projects but this one seems fine and dandy. BTW, what guitar do you have? I have an original 1963 Stratocaster w/ original hardware, pickups, etc. It's worth a ton of money these days (thousands $$$) and to think I bought years ago for $125 from a guy that hated it and wanted a lower model Gibson instead!!
     
  4. dave

    Dave New Member

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  5. moody07747

    moody07747 Member

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    Thanks for all the links, ill have a look at them all.

    killer deal on that guitar. I am just starting on guitar, got a PRS SE (older version) last month but I'm learning it fast even without lessons.

    if you look in my sig like ill have my web page at myspace.com I will be putting up a song in a day or two, I'm working out some of the details in editing now and have to add drums and keys.
     
  6. Dr.EM

    Dr.EM New Member

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    That clean supply posted with the LM317 is good. Something that seems silly to me is the use of a 25v transformer though. That gives around 34v at the input to the regulator! This high input voltage will waste serious power to give a 9v output. Use a 12v transformer instead if you use that design, it will give plenty of voltage, even 9v may do, it would with a lower dropout reg. You may need to up the value of the 1000uf smoothing cap though.
     
  7. moody07747

    moody07747 Member

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    Thanks for the tip

    Also, im going to take a guess and say that they ment a 68K resistor, not a 6k8

    http://www.generalguitargadgets.com/bom/clnprbm.txt
     
    Last edited: Jul 5, 2006
  8. moody07747

    moody07747 Member

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    ok i got 90% of the parts from the list link above but i still have to find the following

    2 - 0.1uF (min. 35V)

    1 - LM317 Transistor


    I tried to get the parts all from allelectronics.com but the 6 - 1N4002 diodes had to come from mouser.com

    as for that 1,000uF cap change, I ordered a 12V transformer and a 2200uF 35V to counter it.
     
  9. Dr.EM

    Dr.EM New Member

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    The diodes arn't too critical, anything 1N4002, 03, 04, 05 etc is fine. Alternatively, for those 4 a bridge rectifier could be used as that is what the diode arrangement is doing (1A, 100v min).

    For the 0.1uF, use ceramic caps, (100n as they'll be listed). They are there to stop the LM317 oscillating and ceramic have the best high frequency bypass caracteristics. Install them as close to the 317 as you can. 25v rating is fine on them seeing as you are using the 12v transformer.

    The LM317 is very common, was it out of stock? It is an intergrated circuit, variable voltage regulator, not a transistor though in case you were searching the wrong terms.
     
  10. moody07747

    moody07747 Member

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    got everything from allelectronics.com.

    i did however find one of my old regulator ICs from that power supply that went from 1-30 VDC back a few months ago.

    its the "LM317T Adjustable Voltage Regulator"

    it looks like it will work so ill give it a try.

    I got the following parts all from AE.com

    (old photobucket link removed)
     
    Last edited: Nov 24, 2006
  11. moody07747

    moody07747 Member

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    OK I just got all the parts in today for the power supply...some from all over the place.

    I layed the parts in a blank board that's about 2" x 1.5" and ran into some problems near the end which I should have caught days ago when I ordered.

    The list of parts seen here
    http://www.generalguitargadgets.com/bom/clnprbm.txt

    Says to get a "6k8" 1/4W resistor

    Whats that?....While on the layout it calls for a "6k81" resistor

    Another one that I found was in the parts list
    A "270"ohm resistor is called for there but on the layout for the diode bridge seen here

    http://www.generalguitargadgets.com/diagrams/ultra_clean_ps_lo.gif

    A 274ohm resistor is in place, what should I use there?


    When I ordered I looked at the parts list and assumed it was meant to be a 68k resistor and got that but looking at the layout and schematic sheets I think its supposed to be a 6.81k 1/4W (in place at r2b )

    http://www.generalguitargadgets.com/diagrams/ultra_clean_ps_sc.gif


    Last time I emailed the guy it took 4 days of waiting for a response and I really don't want to have to wait that long just to make another order which will delay me even more.

    If you have any thoughts on what these parts should be post them.

    Thanks
     
    Last edited: Jul 10, 2006
  12. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Use a 470 or a 1000, it makes very little difference (try reading the tolerance on the side of electrolytics!).

    6K8 is the standard way of listing a 6.8K resistor, the 6k81 is probably a mistake, likewise 274, it should be 270 ohms.
     
  13. moody07747

    moody07747 Member

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    thanks...time to order more parts and play the waiting game.
     
  14. Hero999

    Hero999 Banned

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    You never know it could be 270k ohms, but I agree with you when looking at the circuit.
     
  15. moody07747

    moody07747 Member

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    OOPS!!!

    i made a big edit on that original post...

    i said something about a capacitor then went talking about the resistor...that's what happens when you stay up all night working on things that have to get done lol

    anyways here's how it should be worded:


    Another one that I found was in the parts list
    A "270"ohm resistor is called for there but on the layout for the diode bridge seen here

    http://www.generalguitargadgets.com/diagrams/ultra_clean_ps_lo.gif

    A 274ohm resistor is in place, what should I use there, the 270 or 274ohm resistor?

    its probably one of those that wont make much of a difference but better safe than blowing up parts lol
     
  16. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    What was wrong with my previous reply to this question?.
     
  17. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The project uses a 274 ohm 1% resistor in parallel with a 2k resistor, and a 6.81k 1% resistor in parallel with another 2k resistor.
    I would just use a 120 ohm 5% resistor for the resistor from the output to the ADJ terminal, and a 750 ohm 5% resistor for the resistor from the ADJ terminal to ground. Then its output voltage will be close to 9V.
     
  18. moody07747

    moody07747 Member

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    im not following ya on that...

    you mean take out the 2k, 270, 6.8k, and 2k resistors all together and just use the 120 and 750?

    if im going to under stand anything for this im going to need a wiring sheet made up with the different components in place...
     
    Last edited: Jul 10, 2006
  19. philba

    philba New Member

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    dave, take a look at figure 7 in the lm317 datasheet. http://www.st.com/stonline/books/pdf/docs/2154.pdf the guy that designed that power supply used 4 resistors instead of 2. In the datasheet you will see one resistor between output and Adjust (R1) and one between adjust and ground (R2). the formula for the output voltage is Vout = 1.25(1+ R2/R1) +Iadj*R2. For small R2s, you can ignore the Iadj*R2. What he was trying to do is get specific values of R1 and R2 so he could get exactly 9V. I would suggest you get 1% metal film resistors. R1 = 120, R2 = 732 (those are stocked values of xicon 1% metal film at mouser). This will give you very close to 9V (at least 8.95 but with the Iadj adder, it's almost exactly 9V). edit: note that 750 will get you 9.14V and 720 will get you 8.8V)

    so, remove all 4 resistors from the board. replace the 274 ohm one with 120. Replace the 6K81 one with 732.

    Now, I don't understand why the guy didn't just use a 7809. no resistors needed at all, Unfortunately, the pin out is different from the LM317 so the board won't work.
     
    Last edited: Jul 10, 2006
  20. audioguru

    audioguru Well-Known Member Most Helpful Member

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    An LM317 with the 10uF capacitor at its ADJ pin to ground has typically less than half the ripple of a 7809.
     
  21. moody07747

    moody07747 Member

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    Thanks

    ok so heres the new layout (older photo removed to reduce confusion)

    ill order later in the day...have to get some lists of items out for the mods to the DS1
     
    Last edited: Nov 24, 2006

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