Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Need a DC power supply - amplifier?

  1. Nov 10, 2006 #1
    I need a DC power supply for a project I'm working on.

    I have a Leach amplifier with a monster power supply and heat sinks able to handle it clipping at ~500W/channel. It's just sitting on my floor.

    I also have a 2 16bit 1MHz DACs and 2 16bit 200KHz ADCs attached to a National Instruments FPGA. I'm thinking instead of buying a DC power supply, I can write a program in 10 minutes that feeds a nice sine curve to the amplifier, and just buy a 2 rectifiers and some caps and build a pair of clean full wave rectifier for <$10 and hook it up to the outputs.

    Any immediate reason this is a bad idea? There's no way I'll need more than 2A @ 12V DC from this thing, and it's able to drive a 4ohm load to something like 60+V peak-to-peak, which means 10A @ ~40V DC after a rectifier.

    It's going to be the power source for a switch-mode duty-cycle controlled driver for a tiny servo motor (electronic throttle body from a car that I'm testing on my desk).
    Last edited: Nov 10, 2006
  2. jcsd
  3. Nov 10, 2006 #2


    User Avatar
    Science Advisor
    Gold Member

    I assume you'll use the ADC's to regulate the output voltage? Things to pay attention to: A) feedback loop has enough bandwidth and low enough delay. B) you might operate at a high frequency (10kHz, eg.) to reduce size of filter caps. C) calc. inrush current when you turn it on and check it's within amp ratings. Big caps (relative to frequency) with low ESR will initially look like a dead short across your amp.

    Done properly you should have a very high-quality supply.
  4. Nov 10, 2006 #3


    User Avatar

    Staff: Mentor

    Buy a wall wart from Radio Shack.
  5. Nov 10, 2006 #4


    User Avatar
    Science Advisor
    Homework Helper

    Run an extension cord to your car battery.
  6. Nov 11, 2006 #5


    User Avatar
    Science Advisor
    Gold Member

    You're going to deprive 280Z28 (I'm going to guess he's a fan of fast cars) of the immeasurable joys of design and experimentation. He indicated in the OP that he'd like to do this instead of buying a supply. Is it sensible? No. Practical? No. A good use of time? No. That doesn't mean he shouldn't do it :biggrin:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook