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how to avoid using a jfet buffer? Answered

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I am trying to build an overdrive circuit, and it requires a jfet buffer, which i do not have, nor does radioshack (to the best of my knowledge), i do however have multiple mosfet buffers.  could i use these in place of the jfet, and if not, is there a way to remove the buffer altogether.  the scehmatic and diagram are here, i am trying to build the big daddy. thanks in advance!

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seandogue (author)2010-01-21

go to mouser (or similar distributor) and look for it for an online purchase. You could use a mosfet but the jfet was designed in for a reason. Unless you can match the electrical characteristics of the jfet, the mosfet will not be a sufficient substitution to achieve an accurate duplication of the effect. Mosfets are in general similar  (they are both forms of the fet transistor structure, rather than biploar), but they are not equivalent to jfets. Close enough isn't always close enough, and when it comes to musical instruments and effects, that applies rather well.

Mouser sells in small quantities and last I checked, unlike Digikey and many others, they still have a very low minimum purchase rule


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fatfoohy (author)seandogue2010-01-22

thanks for that, but i wasn't looking to duplicate the effect anyways, i was just looking for a way to get that circuit to work without a jfet. thanks again

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seandogue (author)fatfoohy2010-01-22

Well, then you can use a mosfet preamplifier stage or substitute an opamp...there are alot of things you can do to replace the preamp. As for the specifics of such a substitution, one would still have to know the characteristics of the jfet and replace the jfet subcircuit accordingly.

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