Thanks guys. All good suggestions, but the REAL problem is following
directions!
I omitted the extra series resistance that John recommends in his
MOTM build-up. Once I changed the 220K on the wiper of the freq pot
to a 470K, all was well. It may help others to note that I matched
the 2n2222's in the circuit (all have hfe 0f 148. These are old
Motorola metal cans) and dug through my 2n3906's until I found one
with a low hfe - about 155 - and low noise.
In fact all is VERY well! This is a neat filter. Right now I've got
a patch using two VCO's, the BP and LP inputs of the filter with the
freq knob below the lowest fundamental of the VCO's. The resonance
is fairly low and the EG is set for a quick attack, medium decay and
minimal sustain and resonance. The VCO patched to the BP input has a
slight vibrato from the FM input. It sounds like an alien bell
tolling. Cool stuff!
Thanks again!
Chub
Chub
directions!
I omitted the extra series resistance that John recommends in his
MOTM build-up. Once I changed the 220K on the wiper of the freq pot
to a 470K, all was well. It may help others to note that I matched
the 2n2222's in the circuit (all have hfe 0f 148. These are old
Motorola metal cans) and dug through my 2n3906's until I found one
with a low hfe - about 155 - and low noise.
In fact all is VERY well! This is a neat filter. Right now I've got
a patch using two VCO's, the BP and LP inputs of the filter with the
freq knob below the lowest fundamental of the VCO's. The resonance
is fairly low and the EG is set for a quick attack, medium decay and
minimal sustain and resonance. The VCO patched to the BP input has a
slight vibrato from the FM input. It sounds like an alien bell
tolling. Cool stuff!
Thanks again!
Chub
Chub