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evengravy



Joined: Aug 10, 2013
Posts: 3
Location: ireland

PostPosted: Wed Nov 18, 2015 3:19 am    Post subject: Sorry Reply with quote  Mark this post and the followings unread

Hey, Sorry for reviving an old thread but I think this one is worth revival. I've built one of these to test and am having some issues.

I think I received some dead/fake CA3080s which are being re-ordered from a more reliable source but the main issue is the Fets are shorted between Gate and Source. Both are the same when testing continuity (3080 IC pins 6 and 7, IC's removed).

Could anyone tell me if this is usual for dead Fets? Do they short in this way? I think the fake chinese parts may have caused it to begin with. I cant find any PCB shorts at all.

Also, the Drain and Source are swapped in this layout vs. the schematic, I'm assuming it doesn't matter that much in this case (jfet buffering?)

Thanks and regards,
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synnys



Joined: Mar 26, 2018
Posts: 1
Location: netherlands

PostPosted: Mon Mar 26, 2018 10:58 am    Post subject: Reply with quote  Mark this post and the followings unread

hi everyone,

i also like to revie this topic, even 3 years later... hopefully anybody will read this.

I've got a weird problem with my build... a bit hard to explain, so i made a video.

https://www.youtube.com/watch?v=42atkVBsG34

The problem is that:

- resonance is out of control
- resonance pot controls the frequency of the resonance?
- also does this in a reversed

anybody got a suggestion?

I'm using 2x CA3080EZ from Reichelt and TL071 instead of the LM301, with no 33pf caps.

The youtube video is pretty high resolution, so you can see the PCB quite clear when paused.
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