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previous: funkymonkey Hi,I'm trying to bu... -- 9/12/2000 7:03 PM View Thread

Re: Mu-tron III

9/12/2000 11:07 PM
Re: Mu-tron III
The "0805" is a combination LED / dual LDR. The response of the LDRs seems to be fairly critical to the feel of the Mutron III, at least in my limited experience with building clones of it - all of the cheaper LDRs seemed to be too "slow", and don't give that "liquid" feel.  
Any dual opamps will work, so you can use 4558s, TL072s etc.  
The drive switch changes both the sensitivity of the envelope detector and the polarity of the LED-driving signal simultaneously, but you can just use a SPDT switch and substitute a pot (say 100k) in for the selectable sensitivity resistors instead.  
As you also guessed, the range switch is a DPDT that changes the two caps in the state variable filter .... of course, you can change this to a rotary switch to select more than two different cap values for the range  
This site has a schematic including these mods and others to work with NSL-32 LED/LDR packages:  
This site has the schematic and PCB layout for the Bassballs, which might be an easier to get working in an acceptable manner:  
No doubt RG's Neutron would be the way to go if you are looking for an easier building experience, and I seem to remember he said something about including discussion of a few options for getting the LED / LDR interaction just right.  
Good luck! Envelope filters rock ... errr ... funk. :)  

funkymonkey The Neutron - R.G. Keen -- 9/13/2000 12:17 AM