Allison
Agreed about noise from all sort of electronics.? We live in a world full of it, some of our
own making.?
I broke open the USB charger module (1) to see what was in it, and (2) so others would
not have to do the same.? Now that I know what is inside and how it works I can simply
purchase those little 5V chargers and use them much like we have done with wall-warts
for many years.? A USB cable from the dollar store and small test equipment is easily
and conveniently powered.?
These USB chargers seem to operate at around 50 KHz (the pulse rate varies depending
on current load), but do not radiate strongly.? Opening one up and adding 0.1 mfd across the
5V output quieted it down to almost nothing being radiated.?
The 5V output is unexpectedly stable with varying load, at least on these units from a local
Dollar Store.? Since Li-ion cells act like big capacitors I tried using one of these 5V chargers
to power a Pixie based telemetry system that has Li-ion backup power.? Result is gratifying,
no switching transients, and It works just like it does when running on Li-ions charged by a
pair of small solar cells.? The telemetry system runs on Pixies at 160 to 190 KHz but no
noticeable interference from the 5V charger.?
Of course the 5V output is excellent for Arduino Nano? or Arduino Pro-mini based test
equipment.?
Arv
_._
