Electricpower
n00b
- Joined
- May 31, 2011
- Messages
- 20
I am a bit disappointed with all these review sites that are doing power supply testing for the noise and ripple figure because ALL OF THEM ARE DOING IT WRONG!!!!!!!!
When measuring for noise and ripple of a power supply, the following should be considered:
If you guys doubt me then I suggest a second source for you all here: http://www.youtube.com/watch?v=Edel3eduRj4
Hopefully, all review sites can learn from this error and will correct their testing methodologies in future review of power supplies. They will also have to revisit all power supply reviews to account for their mistakes.
They all had to do the same for video card testing ever since frame time and pacing came about from techreport guys.
When measuring for noise and ripple of a power supply, the following should be considered:
- Take into account common mode noises such as lighting, other power supplies, or any other source of EMI radiation or else you get the false readings!!!!!!!! Point number three will go into details on how to help with this issue.
- Follow the standard for power supply noise and ripple test with a 20 MHZ CAPABLE OSCILLOSCOPE, the Stingray USB is oscilloscope is ABSOLUTE GARBAGE!! At 250 KHz bandwidth you might as well be driving down the road blind as a bat because you are missing all of the other noise and ripple elements of the power supply because of the cutoff limit of the oscilloscope!!! Also, be sure to specify the load current at which the noise and ripple was taken at!
- Need to use a DIFFERENTIAL PROBE to make a PROPER measurements of noise and ripple of power supplies to help eliminate common mode interference!! Single ended probes are a POOR CHOICE. If you cannot afford a differential probe then use two single ended probes with the ground leads disconnect and terminated with 50 ohm load resistors!! You then use the math function to subtract the two waveforms to come up with the "TRUE" waveform that the supply is putting out.
- Make sure the probe is set to X1 and not X10 when performing noise and ripple test of power supplies.
- Finally, be sure that the load you are using is LOW NOISE. The load can put noise onto the power supply rail!! Resistors are the best choice compared to electronic load testers!
If you guys doubt me then I suggest a second source for you all here: http://www.youtube.com/watch?v=Edel3eduRj4
Hopefully, all review sites can learn from this error and will correct their testing methodologies in future review of power supplies. They will also have to revisit all power supply reviews to account for their mistakes.
They all had to do the same for video card testing ever since frame time and pacing came about from techreport guys.