AC/DC combined propagation, separation, rectifier question

Discussion in 'General Electronics Chat' started by rasqual, Feb 21, 2011.

  1. rasqual

    Thread Starter New Member

    Feb 21, 2011
    Hi all. New guy.

    My application requires generating low voltage AC power at 20 to 25 kHz. This is coupled with an independent 0 to 20 VDC supply, and both are transmitted over a pair (under 100 yds). At the far end, the AC is picked off, rectified and regulated to a bit over 5 VDC, supplying 1+ A for consumption by electronics. The independent DC powers a motor (the high frequency AC was chosen to be invisible to the motor).

    To date I've combined an oscillator with a small audio amplifier, coupled the output to the DC line through a 6.8 uF Polyester cap, picked the AC off again at the far end through an identical cap, rectified and regulated it.

    It works OK. I'm guessing at some things, though. For example, the value of those isolation caps. Why did I choose 6.8 uF? Because I had the darned thing handy. I have no idea how far I can downsize (which I'd like to do, to a minimum physical size cap). I'm simply entirely ignorant about how to calculate cap values for power transmission.

    I have a few questions I'm puzzling over, but there's one more requirement that will narrow this post to one question for now. The "package" that consumes the AC is not very well ventilated, nor can it be. I have to minimize heat. The regulator's producing some, true enough. But tuning the AC amplitude I'm transmitting helps with that.

    But that darned rectifier. Here's my question: would a Schottky rectifier generate significantly less heat? There's only one such bridge at Mouser that would do the trick.

    Your mission, should you choose to accept it, is to determine from across time and space whether I add this inexpensive device to my shopping cart at Mouser. ;-)

    Seriously, from what I've found on-line I can only infer that I might avoid some heat by going with the Schottky. Does anyone know from experience what I can only guess about out of ignorance? Argh.
  2. tgotwalt1158


    Feb 28, 2011
    Hi rasqual!
    Why you don't use Tesla Coil instead. There are lot of projects are available. Just modify one which suits to your requirement.