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Topic: Seeking full wave bridge rectifier with the lowest forward voltage drop... (Read 447 times) previous topic - next topic

holesflow

Experts,

Google searching with the right keywords doesn't match their algorithms well. Most everything I see is 1volt/leg, and I'm trying to charge a battery (powering a μC) with low-power AC from RF (think Qi/Energy harvesting, etc.). what Since the power demands are low, I'm hoping the possibility of using SMD will make more efficient alternatives possible. 


Would you go 1/2 wave, having that make up for 1 less leg's loss?

Problem is, I can't even figure out how to search for such a critter. 

Thoughts?

TIA!

"A wise man can learn more from a foolish question than a fool can learn from a wise answer". ~ Bruce Lee.
"If you drop it and it breaks, it was good." ~ Mr. William Lehr, my Electronics VoTech Teacher, on testing vacuum tubes. RIP

DaveEvans



Paul_KD7HB

SMD is only efficient for circuit board use. Before you go too far searching, what AC voltages are you using? What frequency? And what charging current? Germanium signal diodes may work well.

Paul

MasterT

Try "schottky diode rf detector" as your google search pattern.

MarkT

Schottky diodes or germanium diodes or back diodes have the lowest rectification loss.  For RF you need
a diode that's fast enough for the frequencies involved.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

ted

google - free rf energy.
include youtube
What is your the RF source ?

holesflow

Thanks experts for the great ideas!

By the comments, I see I succeeded at being too concise. A friend asked me to investigate Qi charging, with him thinking about a "generator" pad under a mouse pad, and a rechargeable mouse with a receiver. Problem is, they are all too big COTS, as they are made for cell phones. They're cheap, but not small.

Being that coil size has a huge impact on received RF (albeit in the KHz range), I took a look at what makes up these receivers, and it ain't much. Just a rectifier and regulator, as far as I can see. I don't think I could lose more in a FW rectifier than gain by only rectifying 1/2 wave, but that is just a gut feeling, and it's based on low voltage assumptions, where higher voltage can take the 1vdc/diode loss no problem..

This is why I mentioned the N-Channel MOSFETs as rectifiers, with some spec sheets looking at well under 1/2 volt total forward voltage loss at lower voltage. 

Does this help?

TIA!
"A wise man can learn more from a foolish question than a fool can learn from a wise answer". ~ Bruce Lee.
"If you drop it and it breaks, it was good." ~ Mr. William Lehr, my Electronics VoTech Teacher, on testing vacuum tubes. RIP

ted

http://www.longrangelocators.com/forums/showthread.php?t=18464
Your transmitter, make as described then you can change diameter of the coil.
C2=22nF, VR1 = tune for resonance.

ted

http://vu2lvj.blogspot.ca/2013/11/a-passive-field-strength-meter.html

Your charger, doesn't need ANT1 and C1, instead C3 your battery, everything on right of C 3 - remove. L as in transmitter

holesflow

http://www.longrangelocators.com/forums/showthread.php?t=18464
Your transmitter, make as described then you can change diameter of the coil.
C2=22nF, VR1 = tune for resonance.
Thanks, Ted!
Funny that the comments to that post all claimed it was useless nonsense... :)
"A wise man can learn more from a foolish question than a fool can learn from a wise answer". ~ Bruce Lee.
"If you drop it and it breaks, it was good." ~ Mr. William Lehr, my Electronics VoTech Teacher, on testing vacuum tubes. RIP

ted


TonyWilk

Google searching with the right keywords
Synchronous Rectification


Sometimes called: Active Rectification

Yours,
  TonyWilk

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