Power supply help

Discussion in 'The Projects Forum' started by Zyhpheigh, Dec 15, 2012.

  1. Zyhpheigh

    Thread Starter New Member

    Dec 15, 2012
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    Hi all, I have been making guitar pedals and amplifiers for a couple of years, most of which have been get schematic and follow it no real need to think about what goes where and why. Recently I have started making pedalboards and I need a power supply to run them off of. I started doing research and I realized that the power supply is the easiest thing to make but there aren't any good schematics out there. So I defer to all of you. I have a lot of questions so bare with me. I found this schematic http://www.generalguitargadgets.com/diagrams/ss-ps4_sc.pdf
    It's a good starting point, but I need higher amps so can I still use it and just change out my transformers and regulators? The commercial power supplies can combine two outputs into one i.e. two 9v 100ma outputs into an 18v 100ma output, how does that work? And is that possible in this application? Any ideas and help are greatly appreciated.
     
  2. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    How can we suggest a power supply if you don't define what voltage(s) and load currents are required to run the device in question? Is it 9V or 18 or something in between?
     
  3. Zyhpheigh

    Thread Starter New Member

    Dec 15, 2012
    3
    0
    Oh sorry, I need 4-9v at 100 ma, 4- 12v at 60 ma. I would love it if I could combine two in to 18 v and 24 v
     
  4. tubeguy

    Well-Known Member

    Nov 3, 2012
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    ????
    So, do you really need 2-9v, 2-12v, and 1 each at 18v and 24v or do you need them selectable (combinable?)
     
  5. #12

    Expert

    Nov 30, 2010
    16,283
    6,795
    I did one of these with a 25.2 volt, 1 amp transformer from Radio Shack, some 78xx regulator chips, 78Lxx chips, 79xx chips, and some 317 regulator chips. The trick part was in using some rows of pins from a computer board where I could use the tiny jumpers to set each output for positive center or negative center. Another important part was an LED that went out when the regulators went into self protect mode because the customer had the wrong polarity chosen for an output.

    The problem I see with your schematic is that the transformer is too small. Everything else will supply 100ma (each) if you just buy a bigger transformer.
     
  6. Zyhpheigh

    Thread Starter New Member

    Dec 15, 2012
    3
    0
    Getting the output voltages is the easy part, I can do it with either a dual tap transformer, a transformer and voltage regulators and rectifiers, or a different transformer for each voltage. The biggest question I have is how can I combine the voltages of two outputs into 1 output of double the voltage i.e. say I had a 9v dual tap transformer which I ran to two different rectifiers and then to two different 9v outputs, is there a way to combine the two separate 9v outputs into one 18v output? The reason I ask is because having a bunch of different transformers inside of my pedalboard would take up a lot of space and generate a lot of magnetism which would distort my signal, and using a different regulator for each would generate a lot of heat and I don't have a lot of space for a fan or anything else. If I could use a dual tap transformer at 12v and 9v and have at least three out puts coming From those secondaries is there a way i could daisy chain off of one output and combine the other two into 24 and 18 volts?
     
  7. #12

    Expert

    Nov 30, 2010
    16,283
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    Connect the positive voltage of one supply to the negative voltage of the other supply. They will then be in series with each other and the voltages will add, as long as they are not both using the same secondary.
     
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