nintendar volume drop with lfo

[petey twofinger]

rebuilt both of these twice , replaced all the chips , getting a significant volume drop when the lfo board is connected .

everything else checks out ok .



http://www.paulinthelab.com/2013/03/nintendetar-guitar-fuzz-stripboard.html

http://www.paulinthelab.com/2012/06/nintendetar-add-on-oscillator-veroboard.html



any thoughts ?

i have the power "slaved" and the depth 2 or row "J" on the lfo board connected to row "H" on the main fuzz board . so there is three connections , ground , 9v , and then between j to h .

great sounding circuit , the modulation is subtle but very usable . i would really love to get this ironed out . i could add a switch for the lfo vs pot , then a switchable npn boost , but i think there is something up . at my wits end here .

thanks

[pinkjimiphoton]

bro, on mine the volume is  100k, was built on a pcb paul sent years ago
hth

[ElectricDruid]

Does the LFO board work on its own?

My first guess would be something pulling a lot of current on the LFO board and dragging the voltage down.

If you connect the boards on their own, what do the supply voltages look like?

[pinkjimiphoton]

i went in last nite and played with it some, found that 470n caps instead of 100 seemed to track/sustain better. the lfo has a more useable range too if ya swap out the 47k resistor for 100k. a lot faster, sounds remarkably like a univibed fuzz.

i'm guessing the chip is pulling too much current with the power supplies piggybacked. maybe a decoupling cap is in order.

also try an lm358 for it, other chips i tried didn't work so well. mine was doing that too, lost a lot of output, so i shelved it years ago. the osc wasn't working then either. last nite when i pulled it out its all good. go figure!!