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Proper procedure for reducing ripple on DC power rail? (e.g. oscilloscope reading -> filter design)

Mahonroy

Oct 21, 2014
69
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Oct 21, 2014
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Are you using you oscilloscope properly?

What does the trace look like if you connect the ground clip to the probe tip?

What if you connect it directly across a filter cap on your 7805? (you are using filter caps, right?)
I started questioning this today actually... kind of seems like I'm not. Its a Rigol DS2202A for reference.

I will try connecting the ground clip to the probe tip. I did not put capacitors on the 7805, but there is a 100uF capacitor at the input of the PCB where I spliced the wires in.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Connecting the ground to the tip should give you a nice clean trace without noise.

When you're measuring the noise in the circuit, connecting the ground to the right place is important if you have significant ground currents
 

Mahonroy

Oct 21, 2014
69
Joined
Oct 21, 2014
Messages
69
Connecting the ground to the tip should give you a nice clean trace without noise.

When you're measuring the noise in the circuit, connecting the ground to the right place is important if you have significant ground currents
I just watched a video that explains the noise thing between analog and digital scopes, and how to get a better picture, worth the watch if you use scopes. It looks like this is what I was experiencing:
 
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