Re: Simple question about scope (DS1102E) and AC ripple

Thanks Darren.

I did that with my fluke meter and got 0.001 VAC, so looking good. Much
easier approach you suggested!

I'm really just using this opportunity to learn more about the scope.

On Aug 26, 2013, at 9:37 PM, Darren Finck <dgfinck@yahoo.com> wrote:

240mV sounds OK for unregulated DC just out of the bridge with a decent
size filter cap. After a regulator, you should see muck less ripple than
that.

Note that you can also measure AC ripple with just a (decent) DMM inn AC
mode. It'll show RMS voltage, not peak-to-peak.

Altan Pinball <pinball@aaarfamily.com> wrote:

Thanks! That was helpful. This is the first real thing I've tried with
this scope.

I'm getting about 250 mV as the AC ripple, which I assume ok.

Using ac mode is quite helpful...

On Aug 26, 2013, at 6:02 PM, Rodger Boots <rlboots2@gmail.com> wrote:

Set horizontal to 5mS, trigger to Line mode, and vertical to 10 V and input
coupling to DC. That will get you a good stable starting point. With probe
not connected adjust vertical position to the center of screen. That gives
you 0V in the center.

To see just the ripple, switch input mode to AC and vertical sensitivity to
1V. That gives you a good starting point.

The way you did it before the scope put 0V towards the bottom and 25
towards the top (and 12.5V in the center). When you increased the gain 0V
went off the bottom and 25V off the top.
On Aug 26, 2013 4:44 PM, "Altan (GAPAS)" <pinball@aaarfamily.com> wrote:

>
> Feel kind of stupid asking this, but you knows know this stuff well…
>
> I'm trying to use my DS1102E to look at the output of a bridge rectifier.
> Goal is to see the voltage and whether any AC ripple exists.
>
> So I connect everything up, make sure the probe ground is connected to a
> proper ground, and press the auto button.
>
> I see the voltage is going between about 25V and 26V. This is obviously
> DC.
>
> If there was AC ripple, I assume I would see some large swings down to
> zero and back up, yes? Or do I have that work.
>
> I'm also running into another problem. I wanted to "zoom in" on the area
> between 25V and 26V, just to see what's going on there. The "auto" mode
> picked 5V as the vertical size, so 0V is toward the bottom of the display
> and 25V is toward the top. However, if I use the vertical scale knob and
> change it from 5V to 2V (the next step down), I hear a little click and see
> nothing. Even if I use the position knob to ensure I should see
> something, it's not there. I'm certainly doing something wrong here.
>
> Bottom line: I'd appreciate any thoughts about measuring/viewing AC ripple
> with a scope as well as any thoughts about why I cannot change the vertical
> scale to < 5V in order to look more closely at the bouncing between 25V and
> 26V.
>
> Thanks so much!
>
> … Altan
> www.aaarpinball.com
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Received on Mon Aug 26 21:54:57 2013