Cheap plug packs

[David_AVD]

This may explain why people using cheap plug packs for transmitters, etc have so much hum and rubbish in the audio!

Crappy PSU analysis

[lithgowlights]

That is scary, but not that suprising

[AAH]

It even had the all important CE (China Export) label on it. I was thinking that it was a linear supply originally until he said it was a 1 transistor switchmode.

[AussiePhil]

Nice Work David
 
Also nicely illustrates voltage drop on thin cables.
 
Also not particularly unexpected though but still a bit scary.
 
Phil

[XDU]

it would have been interesting to see the output noise

[David_AVD]

Also not particularly unexpected though but still a bit scary.

Maybe not unexpected to us propeller heads, but the average layman would never suspect it.

I just thought it worth linking to so that people think a little more about what they're buying.

[YAGOONA LIGHTS]

interesting to see David i had this problem myself with a power pack. i plugged the transmitter into a usb port for power instead. thanks to Ryans advice and now i do not have a hum or a buzz in the audio. very interesting to watch.

[Bird]

Also not particularly unexpected though but still a bit scary.

Maybe not unexpected to us propeller heads, but the average layman would never suspect it.
I just thought it worth linking to so that people think a little more about what they're buying.

That would be me on the electronics 
Thanks for the heads up David, nicely done.

[ɟɐsʇǝppʎ]

Great stuff David, that will help people understand that power supplies are not just power supplies, there is a difference in quality