oscilloscope wave shape

[kentroverman]

HI Guys, Need a bit of help.  Made a standard bridge rectifier on a bread board. Conected my probe from my rigol ds 1054z. with the probe on 1X it looks like a proper fully retified wave, but when i change the probe attenuation to 10X the wave looks strange as per attached png file. my welerman oscilloscope on 10X shows the wave as you would want to see a fully rectified wave. any info would be appreciated. Hope i have made myself clear as I am new to electronics.  Thanks

[fubar.gr]

Real life diodes (as opposed to ideal ones) have some series capacitance. When the load on the bridge rectifier is too low (ie high impedance of the oscilloscope in 10x) the capacitance causes these oscillations.

See this: http://en-us.fluke.com/community/fluke-news-plus/electrical/measuring-a-rectifier-with-no-load.html

[kentroverman]

Thank you, very helpfull.

[Phoenix]

You can fix it quite easily with a small load on the output (1k-10k kinda thing).

What I can never work out is why for one half of the cycle the rectified voltage reached zero, it's only ever the other half of the cycle that appears wonky. Intuitively I would expect symmetrical behaviour (same shape each fundamental half cycle).

[kentroverman]

Thanks, I will try a resistor.