EFM Synthesizers
(c) EFM Synthesizers
3510 VCADSR envelope generator
The 3510 vcadsr is based on the EFM VC-RADSR. It is a
simple low cost solution to the usual high cost and
complexity of voltage controlled adsrs.
When Q7 is turned on by a gate the collector goes low. C5
is charged and quickly discharges. A low going pulse is
applied to the 555 trigger input on pin 2. Current flow
through Q7 causes Q8 to turn on and holds the 555 reset
pin4 high. R25 holds pin9 of the 4052 U2 high as long as
there is a high gate.
The 555s output goes high and holds pin10 of the 4052
high. The 4052 switches pin3 to pin4 and pin13 to pin 11.
The voltage bias on Q5 controls the current flow from Q6s
collector through R17 to the roll your own OTA (Q1,2,3,4).
(see VCF1-3521 for a loose description) In turn controlling
the amount of current used to charge C3.
When the voltage on pin1 of U2a reaches the 555s reset
threshold (U3 pin5). The 555s output (pin2) goes low and
so does pin10 of the 4052 (U1)
Q5s bias voltage is switched to pin4 (decay) and the ref
voltage used to set the charge for C6 is switches to pin15
(sustain).
Sustain
VCADSR - 3510
3510 - ADSR
EFM Synthesizers
Gate
Out
Attack
Decay
Sustain
Release
Out
When the gate is removed. Q7 turns
off. Q8 turns off and sets the 555s
reset pin low.
Q5s bias voltage is switched to pin1/5
(release) and the ref voltage used to
set the charge for C3 is switches to
pin12/14 (ground) and C6 is
discharged.
An attack, decay, sustain, release
envelope develops on U2a pin1.
