Voltage ripple

[Hammy]

I'm measuring the output ripple on my flyback (60 kHz @10W). I'm using
2 polymer aluminum caps 16V 470uf 9mohm 100 kHz ESR. The peak
secondary current is 5 Amps full load this should give about 35mV
ripple. I'm measuring 140mVpp ripple on the output. I'm not using the
ground lead from my probe but the small wire; I'm also taking the
measurement right in the terminal blocks. Is the spike just RF pickup
from the leads? I've tried bypassing it with leaded ceramic caps based
on an FFT with limited success.

Any suggestions?

Heres a capture of the scope measurements.
CH1 is the output ripple CH2 is the current sense signal.

http://i29.tinypic.com/1493upl.jpg

Thanks

 

[Phil Allison]

"Hammy"

I'm measuring the output ripple on my flyback (60 kHz @10W). I'm using
2 polymer aluminum caps 16V 470uf 9mohm 100 kHz ESR. The peak
secondary current is 5 Amps full load this should give about 35mV
ripple. I'm measuring 140mVpp ripple on the output.

** OK - so far.

I'm not using the
ground lead from my probe but the small wire;

** Huh ??

Try using a co-axial cable ( with BNC on one end) instead of a scope probe.

Might lose that RF glitch altogether then.



...... Phil