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Assembly

Assembly Instructions

  1. Place and solder U2 (LM13700 SMT package)
  2. D1 and D2 (1N4148)
  3. Horizontal resistors R3, R6, R9, R12, R15, R18
  4. Socket for U1 (DIP-14)
  5. Disc capacitors C1, C2, C3-C5, and C7-C9
  6. Transistors Q1 and Q2 (BC557)

  7. Vertical resistors

    • R1, R10
    • R2, R11,
    • R8, R17
    • R4, R13
    • R5, R7, R14, R16,
    • R19, R20 (ferrites)

  8. D3 and D4 (1N5819)

  9. Electrolytic capacitors C6 and C10
  10. Power connector J7
  11. Trim pots RV1 and RV2 (opposing orientations for equivalent trim direction)
  12. Audio jacks J1-J6
  13. Control pots RV3 and RV4

Measurement and Calibration

Calibration: apply a test signal (440Hz sine, 8Vpp) to the audio input and a DC 1V level to the CV input. Adjust the trim pot until the output is balanced (mean voltage \simeq 0V).

Measurement: apply a test signal (440Hz sine, 8Vpp) to the audio input and vary the DC level to the CV input.

CV (V) Output (Vpp)
1.0 1.20
2.0 2.24
3.0 3.36
4.0 4.32
5.0 5.36
6.0 6.40
7.0 7.44
8.0 8.48
9.0 9.52
10.0 10.72

The linear fit of the gain response is

A = 0.017 + 0.13V_{cv}

where A is the gain in V/V and V is the CV input in Volts. With R = 56k\Omega in the output stage, the gain at 8V CV input is expected to be 1.04 V/V. The measured gain at 8V CV input is 1.06 (within 2% of expected).

image

BOM

Download (.csv)

Reference Value Qty
C1,C2 220p 2
C3,C4,C5,C7,C8,C9 100n 6
C6,C10 10u 2
D1,D2 1N4148 2
D3,D4 1N5819 2
J1,J2,J3,J4,J5,J6 WQP-PJ323M 6
J7 IDC Header 10P 1
Q1,Q2 BC557 2
R1,R10 68k 2
R2,R11 15k 2
R8,R17 56k 2
R3,R4,R6,R12,R13,R15 100k 6
RV1,RV2 3296W 100k 2
RV3,RV4 RV09 B100k 2
R5,R7,R14,R16 220R 4
R9,R18 1k 2
R19,R20 10R 2
U1 TL074 1
U2 LM13700 1