Hi,
I had this idea of putting together a power supply that would make it possible to run cordless power tools plugged in the wall.
The reason for this is to not waste the batteries' life when wall power is available. (This is a friend's situation...plus his old nicad batteries are getting, well, old)
And it is a good little winter project.
So given my limited electronics experience, I thought a linear power supply would do the job, but I want to know opinions of more knowledgeable people..
The power tools are DeWalt 18v Nicd.
I figured a microwave oven transformer with new 18 volts secondary going into an appropriate bridge rectifier followed by a humongous capacitor (I figured 4 x 33,000uF rated @ 20 A ripple current) would do the trick.
Obviously there are things I haven't considered....and I know a switch-mode power supply would be a lot better, but I am trying to keep it simple, albeit inefficient! (switch-mode is a bit outside my range for now)
What kind of ripple current can I expect for 18 volts @ say 30 amps?
(how many amps do cordless tools actually draw on average?)
Any info would help greatly!
Lucas Riveli
I had this idea of putting together a power supply that would make it possible to run cordless power tools plugged in the wall.
The reason for this is to not waste the batteries' life when wall power is available. (This is a friend's situation...plus his old nicad batteries are getting, well, old)
And it is a good little winter project.
So given my limited electronics experience, I thought a linear power supply would do the job, but I want to know opinions of more knowledgeable people..
The power tools are DeWalt 18v Nicd.
I figured a microwave oven transformer with new 18 volts secondary going into an appropriate bridge rectifier followed by a humongous capacitor (I figured 4 x 33,000uF rated @ 20 A ripple current) would do the trick.
Obviously there are things I haven't considered....and I know a switch-mode power supply would be a lot better, but I am trying to keep it simple, albeit inefficient! (switch-mode is a bit outside my range for now)
What kind of ripple current can I expect for 18 volts @ say 30 amps?
(how many amps do cordless tools actually draw on average?)
Any info would help greatly!
Lucas Riveli