EFM VCADSR - 3510 User manual

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.

EFM Synthesizers
(c) EFM Synthesizers
R1
100K
R2
100K
R3
100K
R4
100K
R5
100K
R6
100K
R7
1K
R8
1K
R9
100K
R10
100K
R11
100K
R12
10K
R13
10K
R14
1K
R15
470K
R16
10K
R17
100K
R18
100K
R19
1K
R20
10K
R21
3K3
R22
470
R23
100K
R24
100R
R25
10K
R26
10K
J1
Sustain CV
A
P1
50K
Sustain
P2
50K
Release
P3
50K
Decay
P4
50K
Attack
B
C
D
E
F
Gate
G
U1
4052
U2
TLO72
U3
555
Q1 Q2
Q3 Q4
U2a
U2b
1
2
3
7
6
5
16
12
14
15
11
1
5
2
4
6789 10
3
13
C3
.01uF
C4
100pF
C6
100uF
+
C5
.01uF
Q7
Q8
D1
C1
0.1uF
C2
0.1uF
T1
50K
0 Adj.
Small Kit
PCB PC Board 1
C1,2 0.1uF Ceramic 2
C3,5 .01uF 2
C4 100pF 1
C6 100uF Ele 1
R1,2,3,4,5,6,9,10,11,17,18,23 100K 12
R7,8,114,19 1K 4
R12,11113,16,20,25,26 10K 8
R15 470K 1
R21 3K3 1
R22 470 1
r24 100 1
D1 1N4148 1
Q1,2,8 2N3906 3
Q3,4,5,6,7 2N3904 5
U1 4052 1
U2 TLO72 1
U3 555 1
Full Kit
P1,2,3,4,5 50K Pot 5
Knob 5
Jack 1/8" 5
L Bracket w/hardware 2
Header 1
Panel 1
Overlay 1
VCADSR - 3510
J2
J3
ADSR
Out
J4
J5
P5
50K
Level
Q5 Q6
Adjust T1 for
zero output
voltage on pin-G
with no gate.

EFM Synthesizers
(c) EFM Synthesizers
+v
Gnd
E
D
B
C
G
F
A
VCADSR - 3510
VCADSR
It's a little more expensive but the 3510
vcadsr is much more capable than the
standard adsr. The 3508 has been a
favorite through the years and we keep it
around because it is a simple, useful,
inexpensive circuit.
VCRADSR
Although not part of this kit it's easy to put
the rate parameter back on. Simply
remove R12 and 13 and connect a 50K
voltage control pot to the loose end of
R11. I even put a pad on the board.
Sustain
3510 - ADSR
EFM Synthesizers
Gate
Out
Attack
Decay
Sustain
Release
Out