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 Forum index » DIY Hardware and Software » Developers' Corner
AS3330 behaving strange :/
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Anonymous301



Joined: Dec 25, 2015
Posts: 4
Location: Germany

PostPosted: Thu Oct 10, 2019 10:28 am    Post subject: AS3330 behaving strange :/ Reply with quote  Mark this post and the followings unread

Hey,
I'm currently trying to build a VCA with an AS3330. I build one of the VCAs according to the datasheet. As i powered the circuit, i saw, that the output signal was weaker as i expected and that this annoying high frequency noise in it.(ass seen on the image). Input was a 5V AC-coupled sawtooth.

I tried multiple things: adding a filter to pin 7 like in the original CEM3330 Datasheet, tying the inputs of the other VCA to ground with resistors, adding many capacitors on the supply.(as seen on the image) But all of this didn't work.
Does anyone have an idea?

Best regards,
Franz Smile


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Last edited by Anonymous301 on Yesterday, at 12:15 pm; edited 1 time in total
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Grumble



Joined: Nov 23, 2015
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PostPosted: Thu Oct 10, 2019 2:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

Did you use a proper ground for your scope?
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Electric Druid



Joined: Mar 13, 2012
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PostPosted: Fri Oct 11, 2019 11:59 am    Post subject: Reply with quote  Mark this post and the followings unread

Grumble wrote:
Did you use a proper ground for your scope?


That was my first thought too. Looks like bad grounding, which happens a lot on breadboard circuits with scope probes flying about all over the place.

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Anonymous301



Joined: Dec 25, 2015
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PostPosted: Fri Oct 11, 2019 12:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Grumble wrote:
Did you use a proper ground for your scope?

Yes, i tripple-checked that already. Sad


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cslammy



Joined: Apr 27, 2018
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PostPosted: Mon Oct 14, 2019 7:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Total guess: if you stripboarded or created a PCB your issue might go away?

I frequently have trouble with grounding, unwanted resistance, cap coupling that doesn't quite work, etc., on breadboards. Maybe because until recently I used a $3 banggood breadboard?

An EE told me when breadboarding always buy a really good bread board (3M for instance, which is expensive) even though I'm tempted to buy the cheapest thing I can find. He says: If the part isn't really nailed in there, and the cheap ones are a bit loosey goosey, you can have all sorts of issues. The 3M ones tend to have more positive contacts.

I did this and have had somewhat better results. Of course this could not be your issue at all.....

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JovianPyx



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PostPosted: Mon Oct 14, 2019 8:46 am    Post subject: Reply with quote  Mark this post and the followings unread

+1 on what cslammy said. I spent some cash on a breadboard system and it was well worth it.

Quality of the breadboard is important, but also pay attention to the conductors you insert. I've had parts not work or not work correctly due to dirt, grease, oil or corrosion on pins or leads.

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Anonymous301



Joined: Dec 25, 2015
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Location: Germany

PostPosted: Yesterday, at 12:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

Sorry for replying late, im finally back home Very Happy
cslammy wrote:
Total guess: if you stripboarded or created a PCB your issue might go away?

This sounds pretty logical to me, since the circuit worked for 5 minutes but then gave up again. And my breadboard is indeed a pretty cheap one, thats for sure. Laughing
I just finished a PCB Design utilizing the AS3330 and two AS3310s, i might get them done until next week.

Best regards,
Franz
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