How to clear output of step up converter ?

[Matthew98]

Hey. I bught a DS0150 mini osciloscope and moded it to have internal battery. Its 700mAh Lipo and Im feeding the scope, which draws 100mAh at 9V by step up converter. but this converter add significant amount of static to the osciloscope. How do i get rid as much of it as possible ? For now im using only 470uF capacitor as filtration ... dunno what to add Thanks !

[bharatcs]

Hi
    Capacitor can only filter the output voltage.Since the step up converter is a switching circuits it will produce electromagnetic interference as it is not shielded and can induce voltages in the input circuitry oscilloscope thus creating static.
To solve your problem you can
  -Try to move the step up converter away from the main circuit
  -Try some shielding method (not sure how to )
  -Proper grounding
 

[Matthew98]

I will try to shield him than.. Mabye aluminum foil will work... I ll have to try
Aluminium and iron plates together make a good shielding, they say...

[Matthew98]

Update : Its not inducted voltage. I have tried powering it from 9V battery and when i turned on the stepup converter and gave it 100ma, the scope was sill clear.
Altough i have figured out something. If I connect the step up converter via long (half a meter ? ) cables, the noise decreases a lot !

[Refrigerator]

if the current draw is only 100mA then you can put a small inductor in series with the boost converter.

[Matthew98]

how many H do you reckon ?

[Refrigerator]

47µH inductor would be a good place to start.
Also it would help if you put about 10µF capacitor between the scope and inductor to ground.

[Matthew98]

Thanks !
So i gave it twice bigger inductor, as i dont have any smaller right now, but it works really well ! I did small module out of it, so it can fit inside with no problems. here is how the module looks


And it scopes quite nice now