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bad stone?

10/1/2002 10:08 PM
Sean K
bad stone?
Howdy Pedal Boffins and congrats on the new,for me anyways,forum.I'm looking forward to another place to hang out and learn things.  
Straight to business,I was talking to a guy last night who is very interested in this particular entity.Something like a phaser that is adjustable,by a wah type pedal mechanism,that is the amount of phase added?,I'd like to make one for him so can anyone point me to a schemo.
10/2/2002 2:52 AM
Jim Jones

Hey Sean,  
Here's a link from Aron's schematic page  
10/2/2002 7:09 AM
Sean K
Thanks Jim,I had a quick look in my catalogue and couldn't find any of those transistors or the J- Fets,any idea of modern eqivalents offhand,I can go searching in old catalogues at the surplus store but if anyone knows offhand.And I would suppose those quad op amps were,and are,TLO74's?  
I did have a look through small bears bunch of transistors thinking he'ed have them but to no avail.I've heard about the 2N4302 somewhere,maybe as a switching J-Fet but the MS 087 and the 2N3563 though SB has a 2N3565?
10/2/2002 11:52 AM
B Tremblay

JD Sleep has a schematic as well, with some corrections IIRC.  
He has confirmed it from the photos on my site of my Bad Stone.  
Which incidentally, only has one transistor.  
Check with JD.  
10/2/2002 9:06 PM
Sean K
Thankyou Chaps,I can see that the newer version is somewhat more to my liking as I can readily find all the required bits but I'll look further at aquiring the peices for the older one.I think its going to be fun designing a board for this one!Incidentally,I would suppose that the two 100k pots for manual control and feedback are log pots while the rate is a linear?
10/4/2002 11:33 AM
Sean K
I've figured out how to make the board and its pretty straight forward except I'm having a few problems understanding the actual power supply in the circuit.Can anybody shed any light on why it seems to be doing slightly weird things like C3 being connected between chassis and earth with the chassis having the - end of the cap?,and the fact that the circuit specs an AC input when one would think it was supposed to be DC.I'm not too clever on whats actually happening in this circuit but if its a clean copy I suppose it will work...Actually I suppose the control pot is linear.
11/6/2002 11:14 PM
Sean K

Its been a while but I've got it mostly worked out to build a PCB but I'm still a little concerned about the difference between chassis and earth.I would suppose that the chassis is a floating reference voltage that is "fluid"within the circuit but the earth or ground is separate but these two "systems" are held in check with each other with the 100uf cap between them.Also I'm thinking it would hurt to supply the op amps with a +/- supply of 18V(+9/-9) for a bit of headroom.If anyones interested in the layout I've done just add your name and addres below this and I'll send it to you.Its hand drawn,as thats how I do my PCB's,and will be top and bottom.

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