I finished it yesterday, but it's not working. Being more specific, it's the nosiest effect I ever heard!!! Using 2N3819 and BS170 it seems to work (I hear the guitar signal, but weaker than the noise), but I have doubts that it compressed the sound (it works almost the same even if I rotated the FET by 180 degree). With 2N5457, 2SK30 and other DGS FETs I got no sound at all.
I rechecked the vero and my build and all seems OK. Maybe I will try to modify it, even other persons have no luck :)
This supposed to be one of the nosiest effects...ever so your build could be working as intended. Looking forward to hear if you find some useful mods.
Here is the schematic. https://i17.photobucket.com/albums/b72/mmarkmm/walcoNoteSustainerMods.gif
Hello, fuzzhead! I know that's considered to be very noisy, but I have serious doubts that be so noisy as my build, because it's unusable. The schematic above is for some mods of JC Mailet (I found them when I searched about WCNS), but JC said that it's not a big deal. Anyway, I will give it another try :)
I replaced the 1.5 K resistor from the MOSFET's drain with a 20K pot and the 330 ohms from the source with a 10K pot. Tweaking both, I've biased a 2SK30, a 2SK170 and a BS170 without noise, but I am not very sure if it compresses the sound or not. The 10K pot from the source seems not to help a lot (I set it very close to the original 300 ohms value), but the 20K pot from the drain seems to be very useful. Anyway, I don't think that I will spend time with it. Clearly, it's a bad design.
The circuit as drawn is incorrect. The fist of the two bipolar transistor amplifiers feeds the output, and the FET works as a variable resistor between the base of the first bipolar transistor and ground. The second bipolar transistor just drives the diode pump circuit (which is shown the wrong way 'round) to give a negative-going bias - below ground - to the gate of the FET.
The veroboard layout is therefore completely wrong.
Thanks for taking a look at this. Managed to find the original schematic in an USB stick which differs a bit to the one I linked to. I can't spot any errors but I need glasses now and then... 2,2M resistors in the layout is pulldown resistors at input and output.
Thank you, Chris! Do you have a corrected schematic? Looking at the last picture from https://reverb.com/item/17934073-walco-chord-and-note-sustainer, I saw something very interesting: you must press the footswitch for sustain! I will ask the seller for a schematic or some gutshots...
I know that 2.2M are pulldown resistors, but I thought that the input one can affect the input impedance and MOSFETs are sensible to that sort of thing. The output one seems to me not useful. Anyway, maybe both are OK. Only a thought of mine :)
I finished it yesterday, but it's not working. Being more specific, it's the nosiest effect I ever heard!!!
ReplyDeleteUsing 2N3819 and BS170 it seems to work (I hear the guitar signal, but weaker than the noise), but I have doubts that it compressed the sound (it works almost the same even if I rotated the FET by 180 degree). With 2N5457, 2SK30 and other DGS FETs I got no sound at all.
I rechecked the vero and my build and all seems OK. Maybe I will try to modify it, even other persons have no luck :)
This supposed to be one of the nosiest effects...ever so your build could be working as intended. Looking forward to hear if you find some useful mods.
DeleteHere is the schematic.
https://i17.photobucket.com/albums/b72/mmarkmm/walcoNoteSustainerMods.gif
Hello, fuzzhead! I know that's considered to be very noisy, but I have serious doubts that be so noisy as my build, because it's unusable. The schematic above is for some mods of JC Mailet (I found them when I searched about WCNS), but JC said that it's not a big deal. Anyway, I will give it another try :)
ReplyDeleteI replaced the 1.5 K resistor from the MOSFET's drain with a 20K pot and the 330 ohms from the source with a 10K pot. Tweaking both, I've biased a 2SK30, a 2SK170 and a BS170 without noise, but I am not very sure if it compresses the sound or not. The 10K pot from the source seems not to help a lot (I set it very close to the original 300 ohms value), but the 20K pot from the drain seems to be very useful. Anyway, I don't think that I will spend time with it. Clearly, it's a bad design.
ReplyDeleteThank you, fuzzhead!
Cool! thanks for your findings and info!
DeleteThe circuit as drawn is incorrect. The fist of the two bipolar transistor amplifiers feeds the output, and the FET works as a variable resistor between the base of the first bipolar transistor and ground. The second bipolar transistor just drives the diode pump circuit (which is shown the wrong way 'round) to give a negative-going bias - below ground - to the gate of the FET.
ReplyDeleteThe veroboard layout is therefore completely wrong.
there's a capacitor between the drain of the FET and the base of the first transistor so that the FET doesn't upset the biasing of the transistor.
DeleteIt's a very crude compressor, and a bit noisy, but if built correctly can work reasonably well.
Thanks for taking a look at this.
DeleteManaged to find the original schematic in an USB stick which differs a bit to the one I linked to.
I can't spot any errors but I need glasses now and then...
2,2M resistors in the layout is pulldown resistors at input and output.
Thank you, Chris! Do you have a corrected schematic?
ReplyDeleteLooking at the last picture from https://reverb.com/item/17934073-walco-chord-and-note-sustainer, I saw something very interesting: you must press the footswitch for sustain! I will ask the seller for a schematic or some gutshots...
I know that 2.2M are pulldown resistors, but I thought that the input one can affect the input impedance and MOSFETs are sensible to that sort of thing. The output one seems to me not useful. Anyway, maybe both are OK. Only a thought of mine :)
ReplyDeleteI've just found the soundclip from Tonefrenzy here: http://www.effectsdatabase.com/model/walco/sustainer#pictures
ReplyDeleteIt sounds good...clearly, we have errors...I will recheck my build.
https://cleveland.craigslist.org/msg/d/elyria-walco-chord-and-note-sustainer/7207929002.html
ReplyDeletehttps://www.thegearpage.net/board/index.php?threads/walco-effects.1722379/
ReplyDeleteNo luck with the Reverb seller :(
ReplyDelete