Radio interferences on my EMS Filter

Thalassa

Hello, anyone know why I have radio interferences on my EMS Filter???

Filter more or lees work nices ( resonance self oscilates, good sound ) but I can hear the radio !!!!

It's funny because even I can change station Shocked

The situation is like this :

Something patched on I1 or I2 ( doesn't matter ) , input level at 0 , andi can hear radio on the output.

Other thing is that if i move the control frequency the station changes, and is more or less louder...

I don't know what to do because I check ground, wires and nothing. If i connect any other module to the VCA I don't have interferences only with ems filter.

Anyone knows how can avoid this interferences??

Thanks

Pablo

radio.wav

Description:

Input a 0 level, with radio on the background, after few second I turn the level knob CW and you can hear the input mixed with the radio interferences

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Filename:

radio.wav

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2.69 MB

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804 Time(s)

radio2.wav

Description:

Just filter out patched to vca, frequency knob full CCW and after few second turn CW, at 85% you can her one big interference -> full CW and again turn CCW -> interference-> full CCW

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radio2.wav

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2.69 MB

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791 Time(s)

Thalassa · Posted: Tue Apr 21, 2009 8:02 am Post subject:

any idea? no? yes? Question

I'm so frustrated Confused

v-un-v · Posted: Tue Apr 21, 2009 8:53 am Post subject:

Maybe someone is trying to tell you something? Wink

Thalassa · Posted: Tue Apr 21, 2009 11:42 am Post subject:

maybe

, it's an amazing filter and also a allow you to communicate with the spirits Idea

v-un-v · Posted: Tue Apr 21, 2009 3:43 pm Post subject:

it's just a thought I had earlier, and I'm probably completely wrong, but one of the diodes used in the ladder, it is a germanium type is it? Perhaps the diode manufacturer mistook it for a signal type? Like a crystal radio set?!

I love the idea that you can "tune" this filter Laughing

Pwrhaps that's a clue? Shocked

Adam-V · Posted: Tue Apr 21, 2009 3:55 pm Post subject:

Dry joints can sometimes cause audio circuits to pick up radio signals. It might be worth your while to double check every solder joint on the board and connecting wires.

Also check that the unit is earthed correctly.

Cheers,
Adam-V

Thalassa · Posted: Tue Apr 21, 2009 4:17 pm Post subject:

Thanks for your reply, I'm feel a bit dumb but also very very happy because filter is working!!!!

The problem was that I've varnished the pcb with an anti-corrosion spry and I didn't realize that the varnish avoid the pcb ground line to make contact with the pcb spacer that make the earth connection. Embarassed

So the solution was just clean the pcb pcb corners with a bit of acetone. Embarassed

.

The audio file is just a demo od the filter that I made with two synthesizers.com vco ,yusynth noise and the EMS filter with external delay and reverb.

EMS-Filter.mp3

Description:

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EMS-Filter.mp3

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4.76 MB

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792 Time(s)

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

Wow, I have just discovered this thread and it's some amazing effect. Do you live close to a Radio Emitter ?

I would have suggested just as is said above that you used germanium diodes instead of silicon diodes... Grounding properly the cicuit solves the problem, good to know.

Cheers.

Thalassa · Posted: Wed Apr 22, 2009 7:13 am Post subject:

In some way was funny because even when filter oscillates I could change the frequency moving my hands over the module without touch it, like some kind of theremin Shocked