Results 1 to 4 of 4

Thread: need voltage controlled power source

  1. #1
    Variable Bitrate
    Join Date
    Apr 2004

    need voltage controlled power source

    I need a voltage source controlled by a 0 to 5 volt input.
    The source must run on 16.5 volts dc, the minimum and maximum voltage must be
    adjustable by 2 potentiometers, for example, one pot would control the
    starting voltage, probably somewhere between 3 to 12 volts when the control
    input is at 0 volts and the other pot would control the max voltage
    somewhere between 10 to 16 volts when the control input is at 5 volts. As
    the control voltage varies between 0 and 5 volts the output would vary
    between the minimum and maximum set voltages. It needs to be able to handle
    about 1.5 amps.

    it needs to be simple and reliable, efficiency isn't important. Can't I take a power transistor, put it on a heatsink and bias it with the control voltage through the potentiometers and some resistors to get the effect I want? I'm just not sure as to how I would exactly do this. This circuit is needed to drive some LED light bars.

    I need this in a bad way, it's for a really cool project that I can't
    disclose yet.

  2. #2
    Variable Bitrate FPeter's Avatar
    Join Date
    May 2008
    Quote Originally Posted by turbochris View Post
    i dont understand, how do you mean the minimum and maximum level... voltage regulators has only one output that is controllable with 1 pot... or do you need two separate line with different voltages? and 1.5Amps on each?
    "case": Skoda Superb Elegance 1.8T
    Asrock G41MH-GE, E2180 2GHz dualcore, 1024MB DDR2/800, Samsung F1 750GB/7200RPM/32MB, M4-ATX, Lilliput FA1011 HDMI touchscreen, ASUS Xonar DG PCI, homemade Quectel L10 USB GPS

  3. #3
    Raw Wave Rob Withey's Avatar
    Join Date
    Apr 2000
    Bedfordshire, UK
    Use an op-amp. If I read correctly what you require is an output that is effectively y=mx+c (where y is output to swing between min and max, x is input to swing between 0 and 5, and m and c are gain and offset set by the opamp circuit).
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.

  4. #4
    Variable Bitrate
    Join Date
    Apr 2004
    This is what I came up with. Could I use a circuit like this?-

    I would adjust P1 until the load had it's minimum required power and then apply 5 volts to the 0 to 5 volt input and adjust P2 until the load had it's maximum required power. Then I hope it doesn't catch on fire and when I vary the control from 0 to 5 volts that I would see the power across the load vary from its min setpoint to it's max setpoint. DO I really need op amps and regulators?

Similar Threads

  1. RR is acting really slow... debug.txt attached
    By ludikris in forum Road Runner
    Replies: 10
    Last Post: 04-11-2008, 01:35 PM
  2. Switching power source by software ?
    By frontliner in forum Coders Corner
    Replies: 5
    Last Post: 03-10-2008, 09:28 PM
  3. Hardware Review: M3-ATX Power Suply
    By Bimmerstyle in forum The Review Palace
    Replies: 8
    Last Post: 03-05-2008, 06:57 PM
  4. Need help understanding efficiency and voltage regulation
    By sansoo24 in forum Power Supplies
    Replies: 3
    Last Post: 04-22-2005, 03:45 AM
  5. Here's an alternative power source....
    By A Boy and his Miata in forum General Hardware Discussion
    Replies: 7
    Last Post: 11-21-2000, 12:44 PM


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts