fet switching an LFO (Tremulous Lune)

[aloupos]

Hi Everyone -- wow, the fall is here in full swing, isn't it??  Cold weather = more effects builds! 

A friend asked me to build a trem with an LFO that is triggered by the guitar signal.  I've build the tremulous lune as a start.  I've noticed that by shunting pin 4 or pin 7 of the op amp (the 4558) I can stop and restart the LFO. 

I was thinking of using a JFET to handle the switching, since I think it's sensitive enough to respond to a signal from a guitar.  So, I'm looking for a really simple normally closed JFET circuit that will open with the signal from the guitar.  I've searched the board and google, but can't seem to find what I'm looking for. 

1.  Can you recommend a snippet of a circuit that does what I need? 

2.  Is the approach mentioned above the best way to start/stop the LFO?  Is there an easier way as a whole to accomplish this? 

Thanks!! 

[aloupos]

Can anyone point me in the right direction?

[R.G.]

See the "Vibra-matic" mod to the EA tremolo. Geofex, http://www.geofex.com, March 16, 2001.