Ok so common ground is effecting my scope and distorting my waveform.
can anyone suggest a way of overcoming this, or a procedure test the
output of a rectifier. my signal generator is intergrated to my scope
so the output of the sig gen is always grounded. as for the input to
the oscilloscope, my probe has a ground lead. This however makes no
differance to output wave if it is attached or not. ( a very small
differance does occure in the shape of the wave but it is negligible )
No, you are grounding the bridge in such a way that it's no longer
a bridge:
+----------+------>+DC
|K |K
[1N4001] [1N4001]
| |
120AC>--------+ +--+ |
P||S | |
R||E | |
I||C | |
ground --------+ +--|----------+
| |
|K |K
[1N4001] [1N4001]
| |
+----------+------>ground
You now only have one diode at work (the one in the upper left). The
two lower ones are shorted out (ground at the left, ground at the bottom)
and the upper right one never sees any positive peaks because it's at
ground.
So you have a half-wave rectifier, and the other three are going to waste.
How to isolate it? Use a transformer. That's what they are for.
Find an audio transformer, or a small power transformer, and use
that between the signal generator output, and the two AC input points
to the bridge. None of the diodes in the bridge will then be shorted
out, and it will work as normal.
Of course, you want to be careful picking the transformer. Best is
a 1:1 so it isolates but doesn't step up the voltage, which could give
you quite high voltages (depending on the input voltage and the step
up ratio of the transformer).
Of course, you could just get a low voltage power transformer, hook
the primary to a line cord, wire the secondary to your bridge, and
then you can do that to examine the output, and have a start on
your power supply.
Michael
