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Topic: How to verify a bridge rectifier's bridge type  (Read 307 times) previous topic - next topic

Daiszy

Hello everyone,,
I am working on a project in which I am trying to measure current from a current transducer (SCT 013-030). I want to convert the output to VDC and connect it to a smoothing capacitor and load resistor. However, the bridge rectifier that I currently have to use (DF005M) appears to be a half bridge, not a full bridge rectifier.

I am seeking some guidance in how to best verify what type of bridge rectifier I have? Because the output signal of the CT is so small, I used a function generator to simulate a stronger input signal (60Hz, 20Vpp sin wave). I connected that input wave to the two '~' pins of the DF005M rectifier. When I connect the '+' pin to the purple channel of my oscilloscope, I understandably get only the positive parts of the wave. However, what confuses me is that when I connect the yellow channel to the '-' pin, I only read the negative parts of the wave.

It was my understanding that a full bridge rectifier inverts the negative parts of the wave. Thus, I am confused as to why a negative signal is even getting through in the first place...

Any guidance in properly implementing teh DF005M (or verifying the need for a different rectifier) would be much appreciated! I have searched online for customer reviews for the DF005M glass passivated bridge rectifier, but have not found any that discuss how to properly implement it. I can't even find manufacturer's resources that provide the internal circuit diagram for the component.

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Wawa

I am working on a project in which I am trying to measure current from a current transducer (SCT 013-030).
I want to convert the output to VDC and connect it to a smoothing capacitor and load resistor.
Why?
A bridge rectifier has a threshold of ~1volt, meaning small currents can't be measured that way.
The common way is to measure/sample the AC wave from the CT directly.
For that you need to bias one side of the CT mid-voltage with two resistors.
Examples/diagrams can be found on this site and on openenergymonitor.org
Seems your clip-on CT has the burden resistor already buildin (1volt output), so don't add that externally.
Leo..

jremington

Agreed, don't use a rectifier of any type, as doing so will severely distort measurements.

This is a good tutorial describing the usual approach: https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/interface-with-arduino

raschemmel

#3
Sep 15, 2019, 05:16 am Last Edit: Sep 15, 2019, 05:17 am by raschemmel
As already pointed out , the max voltage output of the CT is 1V

(there are two output modes, current and voltage. It is easier to use the voltage output)

You might consider using a precision full-wave op amp rectifier and then you can amplify the output of that
with another op amp stage.



Op amp full wave rectifier

TomGeorge

#4
Sep 15, 2019, 07:52 am Last Edit: Sep 15, 2019, 07:52 am by TomGeorge
Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .

Did you google?

arduino SCT 013-030

Thanks.. Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

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