WSG filter problems

[acidblue]

I have an WSG filter on breadboard that I'm passing some Oscillators from a 40106.
The problem is I'm not getting any sound from the output.
Should I be using a voltage divide for the WSG filter?

Also I assume the input would be before the .1uF,(C1), cap to the 750k resistor to pin 2.
Or is that wrong, btw I'm actually using a 1m resistor since I don't have a 750k one,
is that too much?

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[electri-fire]

[acidblue]

The 40106 is on a different bread board.
Both grounds are connected.
R16 and R17 are in place.

I'm using this schematic:
I've left out the volume pots to save space on the bread board

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[adambee7]

I'd omitt the 100nf cap on input to WSG as you already have a cap for AC on the output of the space explorer. In fact try omitting the cap on output of space explorer and keep 100n of WSG. In fact try both ways and see what happens. What the hell its worth a go.

[acidblue]

Seems to work both ways, sounds exactly the same as well.
However not much variation when I adjust the filter pots.
The resonate pot doesn't seem to have any variation.

I'll have to check my wiring.

[kaputtpanzer]

I built a standalone wsg filter on perfboard but i have a constant (ground?) hum in the output signal. It is powered by a 9V battery, input and output are 1/4" jacks. Can you tell me what Parts I should replace and check first???

I also grounded the back of the pots, because if i touched them the hum was getting louder.
If I dont find a bad part, can I use this huminator thing?(http://www.beavisaudio.com/projects/Huminator/index.htm)

[acidblue]

I've a had this happen to me a couple of times and it was always something wired wrong.
Double check your wiring and cap placement.

If everything looks ok and your still getting hum,
Try placing a filter cap on the + power side, a 10uF should do it.
See if that changes anything.

That Huminator might help but seems a bit overkill for just one circuit.
I think it's more for FX boxes that are chained together.

[kaputtpanzer]

OK thank you very much, I check the wiring later. Sorry maybe this is a totally newbie question, but what is the right position for the caps? I built the circuit very narrow on the perfboard. I dont know why but I have the feeling that the big cap (220uf) is broken. I try to replace this one first. Next time I try to built filter circuits on bigger piece of perfboard.

[acidblue]

Larger caps ,electrolyte usually over .1uF are polarized meaning they have to
go + to + and - to - .
They usually come with a stripe down the negative side, so you would place it with
the stripe facing the most negative side of you circuit. make sense?

Smaller caps such as ceramic disk, mylar and others. lower than .1uF, are not
polarized, they can face in any direction.
That is what meant when people say "check the placement of your caps".

It's not uncommon to place a polarized cap in the wrong direction, it happens to everyone.

[kaputtpanzer]

The caps are placed in the right direction. Tomorrow I check the wiring again. And place the 10uf cap between + and ground. Thank you for your help.

[adamon]

acidblue, try adding an attenuator before the input to the filter. If you send in too hot of a signal, the filter will be overdriven and you'll loose quite a bit of the filter's effect (I use 100k pots for the inputs to mine).

[acidblue]

Thanks I'll give that a try.

[-minus-]

I've breadboarded the WSG filter today, and although it works fine, I have grounding type hum issues too. This is the schematic I have used... its the older WSG filter with the single pot.

http://electro-music.com/forum/phpbb-files/wsgschem_130.gif

470pF caps have been substituted with 680pF, but 330pF works too. By turning the pot even with no input, I can hear the filter operating and the hum is still there. I quite like this filter, but would love to find a way to eliminate the hum.

Any suggestions much appreciated!

ps: putting a cap from the output to ground, say 1uF seems to stop the hum, but it then makes the output of the filter seem to loose a lot of its highs

[-minus-]

OK. Think I have solved this!

I have increased the capacitor from 220uF to 1000uF!

Hope this info may be of use to others.

[kaputtpanzer]

cool i will replace it, hope it will work without hum now!

[kaputtpanzer]

No there is still some hum!

[-minus-]

OK Yeah, I actually still have some very slight hum too.... I wonder what this is? I have this on breadboard still, so I'll try a few things out and see if I can eliminate it completely. I'm noticing the hum change when I move my alligator clipped pot around....

[kaputtpanzer]

yeah it is only a little bit of hum but it annoys me, I think i will try tim ecobedos ms20 filter thing or the Q&D filters. But if you figure out something let me know it! Thanks...

[-minus-]

Yeah it is only a little bit of hum... and it annoys me too! I would prefer not to just have to live with it! I was unsure if it was because of the pot not being in an enclosure at present and thus not grounded properly. Hopefully one of us will resolve it... or an answer may yet be forthcoming from someone else!

[-minus-]

Tried the Humminator... on the power input. No luck with that. I figure it is for adaptor power and wont do a hell of a lot with battery supplies.

A fair amount of the remaining hum can be knocked on the head with a 330nF cap across the output socket. This does dampen the high of the filter though. I've eliminated the resistor which goes to the pot to try get the high end back. This works... kind of.

I'm getting sound coming from this filter, even with there being no input plugged into it. I'll ask around a bit and see if a solution can be found!

[kaputtpanzer]

Hmmm I wonder if there is hum if you build the wsg complete on the mfos pcb? If I have a strong signal with a lot of oscillators running through the filter then it is kind of impossible to hear the hum.

[-minus-]

Yes that is a good point. The WSG and filter are always on at the same time, so we would never know if it hummed or not! The WSG is making weird noises all the time after all! I've tried substituting some resistor values in the hope I may solve something by chance... no luck yet.

I simply don't have the knowledge required to diagnose this problem... I could open up my WSG and cut some jumpers and see if the filter part hums !

"You hum it, and I'll play it"!

[kaputtpanzer]

haha no please don`t cut any wires. Anyways it is a great filter but I think I will try another active lpf for one of my projects.