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 Forum index » DIY Hardware and Software » The layout factory
MS-20 LPF clone problem
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palmiarz



Joined: May 22, 2019
Posts: 7
Location: Poland
PostPosted: Wed May 22, 2019 4:07 am    Post subject: MS-20 LPF clone problem
Subject description: it doesn't work		 Reply with quote  Mark this post and the followings unread
Hello everyone! I build MS20 LPF clone LM13700 version (Rene Schmitz project), but it doesn't work (ok, it's work unstable). Signal from my VCO (square) lost on pin 12 LM13700, where it sounds like: https://www.youtube.com/watch?v=rzDJ4xWRdE4. I don't have oscilloscope. Sorry for my english. Cheers!
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ixtern



Joined: Jun 25, 2018
Posts: 145
Location: Poland
PostPosted: Wed May 22, 2019 1:00 pm    Post subject: Re: MS-20 LPF clone problem
Subject description: it doesn't work		 Reply with quote  Mark this post and the followings unread
palmiarz wrote:
Hello everyone! I build MS20 LPF clone LM13700 version (Rene Schmitz project), but it doesn't work (ok, it's work unstable). Signal from my VCO (square) lost on pin 12 LM13700, where it sounds like: https://www.youtube.com/watch?v=rzDJ4xWRdE4. I don't have oscilloscope. Sorry for my english. Cheers!

Please provide a schematic you have used or link to that schematic. Maybe something is wrong with biasing LM13700 OTA.
I am asking for your schematic as I have found one somewhere in the Internet and it's biasing part doesn't make sense for me .
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palmiarz



Joined: May 22, 2019
Posts: 7
Location: Poland
PostPosted: Thu May 23, 2019 1:20 am    Post subject: Reply with quote  Mark this post and the followings unread
Here is Rene's schematic: https://www.schmitzbits.de/ms20.html and here is LM13700 OTA version (which I built): https://www.lookmumnocomputer.com/projects/#/simple-filter . But yesterday I solved problem. I had connected wires between ICs V- pins and next I connected pin from one of this ICs (TL047) to supply voltage. Similarly I had with V+ pins. I disconnected this and connected supply pins to supply voltage independent. I removed decoupling caps also (2x 100nf) - but I have other decoupling caps except that.
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