Splitting incoming power into multiple voltages at the same time

Discussion in 'The Projects Forum' started by TheIdeaCan, Jun 13, 2009.

  1. TheIdeaCan

    Thread Starter New Member

    Jun 13, 2009
    2
    0
    So I'm working on an idea I had and have run into a snag regarding power. I'm attempting to combine two electronic instruments, two effects pedals, and a small photo-theremin circuit together into one unit. I've been able to figure out all the connections between the different circuits but could use some help to figure out how to eliminate the need for batteries or at least reduce them in number without sucking them dry too fast. I've scoured the net looking for a solution, but can't find anything that allows for multiple different voltages to be pulled from one power adapter at the same time (or I'm just using the wrong search terms).

    What I'm trying to combine:

    1. Casio SA-7 keyboard -requires 4 x AA batteries or 6v power supply
    2. Blue Man Group Percussion tubes - requires 4 x AA batteries or 7.5v power supply (not sure why it needs more power if it's plugged in)
    3. Ping Pong Echo FX pedal - requires 1 x 9v battery or 9v power supply
    4. Ibanez SD-9 Super Distortion pedal - requires 1 x 9v battery or 9v power supply
    5. Photo-theremin - requires 2 x AA batteries or can be tapped into keyboard power since it doesn't require much power to run
    I know the easiest scenario would be to use a 3v battery pack (2 x AA), 2 x 6v battery packs (4 x AA), and 2 x 9v batteries, but adding 10 x AA batteries and 2 x 9v batteries is just too many batteries to have to replace. I'd imagine I could run the whole thing off 4 x AA batteries and a 9v battery, but I think that would just drain the batteries down quicker.

    What I would like to be able to do is eliminate the batteries all together without having a stream of wallwarts tethered to the thing to supply power to all the individual components. Is it possible to have one power input that splits the power into different voltages internally? I've got a little bit of electronics know-how. At least enough to figure out how to combine circuits in the correct order and read schematics and wiring diagrams, but figuring out how to split incoming power into multiple voltages confuses me.

    What I'm thinking is the voltage would be split into the following taps:

    1. 3v for the theremin
    2. 6v for the keyboard
    3. 7.5v for the percussion tubes
    4. 9v for the distortion pedal
    5. 9v for the echo pedal
    Would that mean that I would need a 34.5v power supply and a number of voltage regulators or am I not thinking clearly? The main requirements are that whatever I use be relatively quiet (it is going to be used with a musical instrument) and be able to supply all the different voltages at the same time. Any help anyone could offer me would be greatly appreciated. Thanks in advance.
     
  2. leftyretro

    Active Member

    Nov 25, 2008
    394
    2
    "Would that mean that I would need a 34.5v power supply and a number of voltage regulators or am I not thinking clearly?"

    No that's not clear thinking. You just need a voltage source equal or higher then the highest voltage required by a device, 9vdc in your case I believe.

    After that simple voltage regulators devices could drop the 9vdc voltage to that required by the other voltages required, (3, 6, 7.5.) However the total current requirement of all devices needs to be know to properly size the input highest voltage source's current capacity requirement.

    That make sense?

    Lefty
     
  3. Externet

    AAC Fanatic!

    Nov 29, 2005
    761
    57
    Can be done, use a single12 to 14 V DC wall power adapter capable of supplying at least the sum of the milliamperes of all devices, and make a box with regulators to feed all the devices. If needed, attach heat sinks to the regulators.

    (+)---------------------7809---------+9---------7806---------+6------|>|---|>|---|>|---|>|-----+3
    12 to 14V
    DC source
    (-)----------------------------------------------------------------------------------------------------common

    Feed the Casio and the Blue at nodes +6 and common
    Feed the Ping and the Ibañez to +9 and common
    Feed the theremin with +3 and common

    Label. observe polarity and terminate properly the connectors.

    ---|>|--- are 1N4001 diodes
    7809 is a 9V regulator IC
    7806 is a 6V regulator IC
    The regulators need one pin connected to common.

    Miguel
     
    Last edited: Jun 13, 2009
  4. TheIdeaCan

    Thread Starter New Member

    Jun 13, 2009
    2
    0
    Hey guys. Thanks for getting back to me so quickly. I guess I'll need to add up the milliampere requirements of all the different devices to make sure I get a wallwart with the right current output. I'm putting together a parts order, so I'll add the parts Miguel suggested to the list. Since the Percussion Tubes will run off of 6v via batteries, I'd imagine it shouldn't have a problem running with 6v DC. I'll post some pictures on here when I start to make some progress. Thanks again.

    ~Ben
     
  5. Liggy

    New Member

    Dec 19, 2010
    1
    0
    put them in paralell, use nine volts DC , if you know enough about resistance you should be able to take it from here, if not, use hi power rated resistors on each device branch that requires less than nine volts, the actual resistance is low but that makes it safer for you,(less current)the resistors will get warm, honestly, I'm no expert but I think you could probably run the whole thing off of one nine volt (can't be alkaline) but it has to be a heavy duty dry cell type (alkaline batteries run like they ate sugar and then wear out too quickly, heavy duty batteries stay at more of a steady power making them last longer) other than that, pedals like that with 9volts are likely to just turn off one second after turning them on if there is an alkaline battery powering it
     
  6. Len Whistler

    Member

    Dec 10, 2010
    44
    3
    Would this work? I'm a newbie and I saw a voltage divider schematic in one of my books so I figure I would drawing this up. It's untested.

    [​IMG]
     
  7. #12

    Expert

    Nov 30, 2010
    16,338
    6,823
    What you have there is a voltage divider...as you said. It is not a row of power supplies. Now...if you had a power amplifer attached to each of the voltage out places, it would be a row of power supplies. The easier and better way is to buy the regulators that externet spoke about. They supply power without resistors becoming part of the load or interfering with keeping a steady voltage.
     
  8. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    Where's your loads?
     
  9. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    The answer is an unequivocal no. By the way... V3 would = zero as R6 is shorted.

    Voltage dividers are most useful and used mostly where infinitesimal current is drawn from any of the nodes. They simply do not lend themselves to good power distribution. In other words they don't posses Voltage vs Current stability. Besides that, when used to distribute power they're lossy as hell. Might be good to heat your room with though! :rolleyes:

    Back in the 'Old Days' it was not uncommon to encounter voltage dividers because Vacuum Tube circuitry were voltage amplifiers, where plate currents were relatively low, except for the driver & power amplifier stage.
     
  10. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Guys, have you really looked at how old this thread is?

    The OP is long gone, probably never to return.
     
  11. #12

    Expert

    Nov 30, 2010
    16,338
    6,823
    Sorry. I habitually assume people don't answer questions that are years old. It's a beginner's mistake. I did it once, some years ago.
     
  12. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Unfortunately...no. Why do nube's always do this? They join, find the oldest post they can and reply to it. I'll admit that I rarely check to see when the original post was made.... eh! I really do gotta change that!
     
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