Electronics > Electronics

Using a capacitor to smooth out a power supply

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waltr:
O'scopes are better for signals that vary in voltage whereas the DVM is better for DC signals (constant voltage).
Keep playing with your scope. Try looking at clock signals, audio signals and digital signals.
The easiest signals to see are the ones that repeat with a regular period.
Some times it gets a little tricky to get the scope to correctly trigger on what you want to see. This gets easier with experience.

ErikY:
Waltr, thanks.

I actually setup a circuit specifically to try to see some movement.

I setup a simple circuit using a PUT, a capacitor and a mini speaker to generate some oscillation.

When I first hooked up my pocket digital oscope, I was seeing some movement, but the problem was I needed to adjust the voltage and the time on the oscope.

Once I made the adjustments, I could not see anything at all.

Every once in a while, it would start reading again for a tiny blip, but I could not get anything realistic.

At the same time, I saw my multimeter handling it properly, I would see the voltage raise until the PUT hit its threshold, and then drop once the cap discharged to the speaker, but could not get any real wave forms on my digital oscope.

I suspect its a problem with the scope itself, but there is almost no documentation out there for this thing.

I will keep playing around with it though. I have a few days to return it, so if I cannot get this thing working I will return it and invest in a better one.

Thanks again.

waltr:
What is a "PUT"?

If the DVM was seeing a rising voltage then this is typically too slow for an O'scope to easily see.

Try a 555 timer chip wired as a multi-vibrator running at about 1kHz to 10kHz. This will show up on the scope as a square wave when the scope's time base is about 2usec per division. Set the scopes vertical to about 1/10th of the voltage powering the 555.

ErikY:

--- Quote from: waltr on January 15, 2013, 09:50:34 PM ---What is a "PUT"?

If the DVM was seeing a rising voltage then this is typically too slow for an O'scope to easily see.

Try a 555 timer chip wired as a multi-vibrator running at about 1kHz to 10kHz. This will show up on the scope as a square wave when the scope's time base is about 2usec per division. Set the scopes vertical to about 1/10th of the voltage powering the 555.

--- End quote ---

Programable Unijunction Transistor, I was using this to allow the cap to build up to a threshold before discharging to the speaker.

Whats interesting is when I first connect the oscope to this circuit, and I had the scope on the +/- of the cap, I was able to see the voltage line bounce, when it discharged.

Then, when I changed the settings for the time, and the Volts for the channel I was using, the scope just stopped working completely, it showed a flat line with zero motion.

Perhaps I had it on a setting it did not like.

That is a good idea on the 555, I will definitely try that out and see if I can get some readings, and I will change out some resistors and caps to see if I can pick up different waves.

Thanks!

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