Re: MOSFET BRIDGE RECTIFIER

On Sep 11, 7:59 am, legg <l...@xxxxxxxxxxxxxxx> wrote:
On Thu, 10 Sep 2009 08:58:05 -0700 (PDT), john





<conphil...@xxxxxxxxxxx> wrote:
Hi,

The following application note is about building the Bridge Rectifier
using MOSFETs. The link is as follows

http://www.pack44-sandusky.org/FETBridge.htm

<snip>
I build the circuit according to circuit diagram 3. The input to the
signal is 2 volts peak to peak sine wave but the output is half wave
output not the full wave.

The output goes positive for the positive part of the sine wave but
stays zero for the negative part of the input sine wave.  I would
appreciate any advice to solve this problem. The zener diode data
*** is as follows

First of all, circuits depending upon the source voltage for gate
enhancement require source amplitudes sufficient to enhance the gates.
2V peak is unlikely to do this, for many mosfet types. In this circuit
you will need Vgs plus a parasitic diode drop to start, though the
extra diode drop reduces to Vf as enhancement is achieved.

Secondly, as drawn, this schematic does not attempt to peak rectify
the source, which is the usual aim of a power circuit. If you stick a
storage capacitor on the output of the bridge, it will be discharged
by the source as the source returns to or passes through zero volts on
each half cycle.

If vyou just want to enhance the fet for reverse current flow, you'll
need smarter circuitry, though it can be a simple linear circuit
function.

http://www.magma.ca/~legg/20_Years/1994/Simple_Mosfet_Rectifier_Contr...

RL

I'd like to correct your grammar.

"This seriously effects it's suitability"
should read
"This seriously affects its suitability"

Fire away.
.

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