In-Circuit LC Meter
A Prototype Study

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Materials
Component list
Component List
Resistors (All 1%, metal film, ≥1/8W)
R1, R71 = 4.7 kΩ
R2, R4, R34, R35, R36, R37 = 2.2 kΩ
R3 = 1.0 kΩ (1)
R5, R6, R7, R10, R13, R66, R72, R73 = 100.0 kΩ (2)
R8 = 100.0 Ω (1)
R9 = 100.0 MΩ (3)
R11 = 10.0 MΩ (3)
R12, R27 = 1.0 MΩ (3)
R14, R26, R46, R54, R62 = 100.0 kΩ (3)
R15, R28, R53, R55, R57 = 10.0 kΩ (3)
R16, R25, R52, R60 = 1.0 kΩ (3)
R17, R30, R39, R75 = 100.0 kΩ
R18, R19, R20, R21, R22, R31, R40, R48, R58, R59, R63, R64 = 10.0 kΩ
R23, R45, R65 = 1.0 kΩ
R24, R29, R32, R33, R38, R41, R42, R43 = 1.0 kΩ (2)
R44 = 1.0 MΩ
R47, R51 = 100.0 Ω (3)
R49 = 0.0 Ω (3)
R50, R56 10.0 Ω (3)
R61 = 1.0 Ω (3)
R67, R69 = 4.7 kΩ (1)
R68, R70 = 100.0 kΩ (1)
R74 = 5 kΩ trimmer
Capacitors
C1 = 22 nF, low temp. coefficient
C2…C14 = 1 µF, ceramic, multilayer
Semiconductors
D1,D2 = 1N4007, protection diodes
Q1, Q8 = J113, n-j FET switch
Q2, Q3, Q4…Q7 = BS170, MOSFET switch
Q2,Q3 = Si4136DY, MOSFET (4)
U1, U12 = TL084, quad opamp
U2, U3, U13 = MC34072PG, dual opamp
U2, U3, U13 = LM393B +1k collector R, dual comparator (5)
U16 = OPA2182, fast zero-offset opamp
U4, U11 = TL431D, 2.5V reference
U10 = DG413Y, quad MOSFET switch (current drive)
U5 = CD4016B, quad MOSFET switch (sampling)
U7 = CD4001B, quad 2-input NOR
U9 = CD4070B, quad 2-input XOR
U18 = CD4093B, quad 2-input NAND
Miscellaneous
SW1 = rotary switch, 6×2
SW2 = rotary switch, 4×3
SW3 = toggle switch, 2×2
Notes:
(1): Tolerances in these components can be compensated through the amplification and attenuation values inputs in the Arduino program.
(2): The equality of values among these resistors affects the accuracy.
(3): These resistors are critical for accuracy. Use precision (low-tolerance) resistors.
(4): More accurate alternative to BS170, with a lower Ron.
(5): Alternative to MC33172.
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