rectification qustion

[malcolm walker]

When i measure the input and output of a bridge rectifier using a two
channel oscilloscope i loses the negative cycle of input and negative cycle
of out.

The input signal is supplied by a frequency generator about 10 volts, 100 Hz
and used 1N4005 diodes.

Could someone explain why the negative cycle is killed off when i connect
the scope lead to the output of the bridge rectifier.

 

[malcolm walker]

Hi Greg what is happening is that i am lossing the negitave side on the
input and the negitave side is missing from the positive side of the output
i.e. showing only have wave rectification.

 

[DarkMatter]

Hi Greg what is happening is that i am lossing the negitave side on the
input and the negitave side is missing from the positive side of the output
i.e. showing only have wave rectification.

One of the elements contained in the bridge is/has opened, or the
bridge is not configured correctly.

 

[jriegle]

The ground of the scope channels is common and you are shorting out 1/2 of
the wave. Diagram this and you can see why. If the current is strong enough,
you may have cooked a diode. If you still get a full wave on the output with
the scope leads removed from the input, it is okay.
John

 

[Ben Miller]

Hi Greg what is happening is that i am lossing the negitave side on the
input and the negitave side is missing from the positive side of the output
i.e. showing only have wave rectification.

Either the bridge is wired wrong, or you have a bad diode in the bridge that
is shorting the input on the negative half of each cycle. This prevents it
from showing up on the output as well.

Ben Miller
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