Posts Tagged ‘rectifier circuit’

Precision half wave rectifier using op-amp

This circuit provides for right half wave rectification of the input signal.
The op-amp IC no-NE5535 is Dual High Slew Rate Op-Amp, it is used for main of this circuit.
The input signal have two-phase supply are Fist, positive signals is the gain is 0; And second, negative signals is the gain is – 1.
By reverted both diodes no-1N4148, the polarity can be inverted. All resistor values are in ohms.
This circuit supply an accurate output signal, but the output impedance differs for the two input polarities and buffering be needed.
The output must slew through two diode drop when the input polarity reverses.
The NE5535 device will work up to 10kHz with less than 5% distortion.

Full wave rectifier with an op amp IC

This circuit acts rectifier the ACV signal.This circuit usually requires two op-amp, but this circuit uses only one op-amp.
The work is easy when a positive input into, The D1, D2 will does not work. The output is equal to R2 / (R2 + R3).When V1 is the input signal and R2 = R3 = R, we will have the output signal V0 = 1 / 2 V1.
Later, when the negative output signal into. The D2 to conduct, but D1 does not work. When this circuit is the inverting circuit, output has values V0 = R2/R1 V1, where R1 = 2R, and R2 = R, so V0 = 0.5 V1.
This piece was positive, but the same direction, so the output out.

Power MOSFET Bridge Rectifier

The losses in a bridge rectifier can easily become significant when low voltages are being rectified. The voltage drop across the bridge is a good 1.5 V, which is a hefty 25% with an input voltage of 6V. The loss can be reduced by around 50% by using Schottky diodes, but it would naturally be even nicer to reduce it to practically zero. That’s possible with a synchronous rectifier. What that means is using an active switching system instead of a ‘passive’ bridge rectifier.

The principle is simple: whenever the instantaneous value of the input AC voltage is greater than the rectified output voltage, a MOSFET is switched on to allow current to flow from the input to the output. As we want to have a full-wave rectifier, we need four FETs instead of four diodes, just as in a bridge rectifier. R1–R4 form a voltage divider for the rectified voltage, and R5–R8 do the same for the AC input voltage. As soon as the input voltage is a bit higher than the rectified voltage, IC1d switches on MOSFET T3.

Just as in a normal bridge rectifier, the MOSFET diagonally opposite T3 must also be switched on at the same time. That’s taken care of by IC1b. The polarity of the AC voltage is reversed during the next half-wave, so IC1c and IC1a switch on T4 and T1, respectively. As you can see, the voltage dividers are not fully symmetrical. The input voltage is reduced slightly to cause a slight delay in switching on the FETs. That is better than switching them on too soon, which would increase the losses.
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Author: Wolfgang Schubert – Copyright: Elektor Electronics Magazine
http://www.extremecircuits.net/2010/05/Power-MOSFET-Bridge-Rectifier.html

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