* Z:\home\khalils\Downloads\files\data\raw_asc\Electrometer.asc
* Generated by LTspice 26.0.1 for Windows.
* Old Fashioned Electrometer Using Parametric up Conversion\nThese days you should just use a AD549
* 1nA full scale
* 1A full scale
* 100A full scale
* Add for 1A full scale
* 10A full scale
* Add for 100A, 1mA full scale
* 100pA full scale
* 100pA, 1nA, 10nA, 100nA full scale
* 10nA full scale
* 100nA full scale
* Add for 10A full scale
* 1mA full scale
* A 1% mismatch in J1, J2, J3, J4 capacitiances give a 6mV input offset and a 425mV output offset(4.25pA readout error) at 100pA full scale range.\nQ1, Q2, Q3, Q4 require a low drive impedance lest the gain of the loop inverts at high input currents.
* 10V full scale
* Trim to reduce\nerror to a\nfraction of 1pA
* Library below included based on ModelFile attribute of instance XU1 (C:\users\khalils\AppData\Local\LTspice\lib\sym\OpAmps\LT1001.asy)
A1 N006 0 N010 0 0 N006 N009 0 DFLOP Vhigh=0 Vlow=-5 Trise=10n
R2 N003 N002 25K
C5 N029 0 .01
LT2a N007 IN 50
Q10 -V N031 N030 0 2N3906
R22 N006 N005 100
R24 N004 N003 400
JQ2 N032 N009 N028 2N4416
R23 N005 N004 200
C6 N015 0 .01
R11 N021 N025 49.9
J4 N008 N012 N008 2N5432
Q8 N019 N016 N015 0 2N3906
LT3a N001 0 25
C2 0 N002 4n
C13 N014 N013 .1 IC=0
R12 N025 N030 49.9
R7 +V N016 2.5K
J3 N012 N007 N012 2N5432
C21 N013 0 .01
C1 N033 IN .015p
R3 N033 IN 100G
R8 +V N015 1.98K
R6 N029 -V 4.75K
K3 T3a T3b T3c 1.
LT1a 0 N026 100
Q6 +V N018 N022 0 2N3904
D2 N027 N031 1N4148
R21 P001 N025 500
J1 N007 N001 N007 2N5432
V1 +V 0 15
C10 N037 IN 75p
C11 N038 IN 100p
Q7 N016 N023 N029 0 2N3904
R17 N034 IN 1G
C16 IN 0 100p
JQ4 N032 N006 0 2N4416
JQ5 N018 0 N011 2N4416
C15 OUT N013 25p IC=0
K2 T2a T2b T2c 1.
C20 0 N026 1n
C18 N035 IN .4p
C22 N005 0 1n
C12 N017 N013 .05 IC=0
LT3c N002 0 25
R15 N038 IN 100K
V3 N010 0 pulse(-5 0 0 10n 10n .5u 1u)
R10 +V N018 1.2K
C23 N004 0 500p
C14 OUT IN .04p
I1 0 IN PULSE(0 1000p 1m 1u 1u 5m 10m)
D1 N019 N027 1N4148
R16 OUT IN 10G
LT1b 0 N024 100
LT2b IN N008 50
R14 N037 IN 1Meg
C8 N026 P001 .1
K1 T1a T1b T1c 1.
R19 N039 IN 10K
C19 N039 IN 50p
J2 N001 N008 N001 2N5432
R9 N031 -V 4.22K
JQ1 N024 N006 N028 2N4416
C7 0 N011 2n
R4 N022 -V 4.99K
R1 N002 0 500
R18 N035 IN 100Meg
LT1c N032 0 100
LT3b 0 N012 25
R5 N023 0 1K
R13 N036 IN 10Meg
C3 N020 N013 1000p IC=0
V2 -V 0 -15
C24 N003 0 250p
JQ3 N024 N009 0 2N4416
R20 N013 N028 100
C17 N034 IN .2p
LT2c 0 N011 50
Q9 +V N019 N021 0 2N3904
XU1 0 N013 +V -V OUT LT1001 ;pnba In+)In-)V+)V-)OUT
C4 N023 N022 .01
C9 N036 IN 2.5p
.model D D
.lib C:\users\khalils\AppData\Local\LTspice\lib\cmp\standard.dio
.model NPN NPN
.model PNP PNP
.lib C:\users\khalils\AppData\Local\LTspice\lib\cmp\standard.bjt
.model NJF NJF
.model PJF PJF
.lib C:\users\khalils\AppData\Local\LTspice\lib\cmp\standard.jft
.tran 15m
.lib LTC.lib
.backanno
.end

* LTspice schematic (.asc):
Version 4
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WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
WINDOW 123 60 32 VTop 2
SYMATTR InstName C12
SYMATTR Value .05
SYMATTR Value2 IC=0
SYMBOL Digital\\dflop 752 320 M0
WINDOW 0 -10 75 Center 2
WINDOW 3 -97 197 Left 2
WINDOW 123 -56 165 Left 2
SYMATTR InstName A1
SYMATTR Value Vhigh=0 Vlow=-5
SYMATTR Value2 Trise=10n
SYMBOL cap -736 1120 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value .015p
SYMBOL njf 672 1104 M180
WINDOW 0 56 73 Left 2
WINDOW 3 58 23 Left 2
SYMATTR InstName Q2
SYMATTR Value 2N4416
SYMBOL cap 208 1008 M180
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SYMATTR InstName R12
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SYMBOL cap -496 1856 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C10
SYMATTR Value 75p
SYMBOL voltage 976 416 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 -32 56 VBottom 2
SYMATTR InstName V3
SYMATTR Value pulse(-5 0 0 10n 10n .5u 1u)
SYMBOL res -176 512 R0
SYMATTR InstName R8
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SYMBOL res -480 1968 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R19
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SYMBOL cap -736 1792 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
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SYMBOL res -176 1088 R0
SYMATTR InstName R9
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WINDOW 0 4 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName T2b
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SYMATTR Type ind
SYMBOL cap -896 528 M90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C16
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMBOL res -480 1520 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMBOL res 448 288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 100
SYMBOL cap 192 912 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
WINDOW 39 60 32 VTop 2
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WINDOW 3 61 46 VCenter 2
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SYMATTR Value 2N5432
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SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL cap -32 320 R0
SYMATTR InstName C24
SYMATTR Value 250p
SYMBOL cap 1008 800 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
WINDOW 123 60 32 VTop 2
SYMATTR InstName C3
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SYMATTR Value2 IC=0
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SYMATTR InstName R4
SYMATTR Value 4.99K
SYMBOL cap -784 848 M180
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WINDOW 3 24 8 Left 2
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SYMATTR InstName R6
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
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SYMATTR Value 2N5432
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SYMATTR Value 2N4416
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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WINDOW 0 0 32 VBottom 2
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WINDOW 123 60 32 VTop 2
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SYMBOL res -720 1904 R90
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WINDOW 3 32 56 VTop 2
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SYMBOL cap 944 880 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
WINDOW 123 60 32 VTop 2
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SYMATTR Value2 IC=0
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WINDOW 3 61 34 Left 2
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SYMATTR Value 2N3906
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WINDOW 0 1 70 Right 2
WINDOW 3 2 37 Right 2
SYMATTR InstName T1c
SYMATTR Value 100
SYMATTR Type ind
SYMBOL cap -736 1568 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
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SYMATTR Value 2.5p
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WINDOW 3 24 8 Left 2
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WINDOW 0 56 24 Left 2
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SYMATTR InstName Q1
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMBOL ind2 -432 368 R0
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WINDOW 3 -7 76 Right 2
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SYMATTR Type ind
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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WINDOW 3 32 40 VTop 2
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WINDOW 39 53 40 VTop 2
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SYMATTR Value PULSE(0 1000p 1m 1u 1u 5m 10m)
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 100
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SYMATTR Type ind
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WINDOW 0 0 72 Right 2
WINDOW 3 2 38 Right 2
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SYMATTR Value 100
SYMATTR Type ind
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SYMATTR Value 2N3904
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WINDOW 0 34 48 VCenter 2
WINDOW 3 61 46 VCenter 2
SYMATTR InstName J1
SYMATTR Value 2N5432
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WINDOW 0 1 37 Right 2
WINDOW 3 -2 74 Right 2
SYMATTR InstName T3a
SYMATTR Value 25
SYMATTR Type ind
SYMBOL cap -368 1056 R0
SYMATTR InstName C5
SYMATTR Value .01
SYMBOL cap -736 1344 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C17
SYMATTR Value .2p
SYMBOL diode -176 960 R0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL pnp -224 752 M180
WINDOW 0 59 68 Left 2
WINDOW 3 61 34 Left 2
SYMATTR InstName Q8
SYMATTR Value 2N3906
SYMBOL ind2 -656 448 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 10 55 VBottom 2
SYMATTR InstName T2c
SYMATTR Value 50
SYMATTR Type ind
SYMBOL njf 528 1104 R180
WINDOW 0 39 90 Right 2
WINDOW 3 35 7 Right 2
SYMATTR InstName Q4
SYMATTR Value 2N4416
SYMBOL cap -496 1408 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C14
SYMATTR Value .04p
SYMBOL cap 128 320 R0
SYMATTR InstName C23
SYMATTR Value 500p
SYMBOL voltage 352 576 R0
SYMATTR InstName V2
SYMATTR Value -15
SYMBOL njf -800 384 R90
WINDOW 0 34 48 VCenter 2
WINDOW 3 61 46 VCenter 2
SYMATTR InstName J3
SYMATTR Value 2N5432
SYMBOL res -624 576 R0
SYMATTR InstName R10
SYMATTR Value 1.2K
SYMBOL Opamps\\LT1001 992 944 R0
WINDOW 3 -40 153 Left 2
SYMATTR InstName U1
SYMBOL voltage 256 576 R0
SYMATTR InstName V1
SYMATTR Value 15
SYMBOL ind2 -816 352 M90
WINDOW 0 4 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName T2a
SYMATTR Value 50
SYMATTR Type ind
SYMBOL npn -336 816 R0
SYMATTR InstName Q7
SYMATTR Value 2N3904
SYMBOL cap -496 2080 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C19
SYMATTR Value 50p
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SYMATTR InstName R1
SYMATTR Value 500
SYMBOL cap -128 624 M90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C6
SYMATTR Value .01
SYMBOL cap -496 1632 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C18
SYMATTR Value .4p
SYMBOL res -32 816 R0
SYMATTR InstName R11
SYMATTR Value 49.9
SYMBOL cap -432 848 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C4
SYMATTR Value .01
SYMBOL res 288 288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R23
SYMATTR Value 200
SYMBOL res 144 912 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R21
SYMATTR Value 500
FLAG 256 688 0
FLAG -272 416 0
FLAG -368 416 0
FLAG 336 1040 0
FLAG 400 992 0
FLAG 464 992 0
FLAG 352 688 0
FLAG 256 576 +V
FLAG 352 576 -V
FLAG 992 960 +V
FLAG 992 1056 -V
FLAG 944 1024 0
FLAG -1200 240 0
FLAG 1280 1008 OUT
FLAG -656 432 0
FLAG -448 368 0
FLAG -160 416 0
FLAG -688 832 0
FLAG -400 976 0
FLAG -352 1136 0
FLAG -48 640 0
FLAG -16 1200 -V
FLAG -16 512 +V
FLAG -768 864 0
FLAG -816 544 0
FLAG -912 240 IN
FLAG 224 1040 0
FLAG 1088 416 0
FLAG 832 480 0
FLAG 864 1088 0
FLAG 304 400 0
FLAG 144 400 0
FLAG -16 400 0
TEXT 792 1392 Left 2 !.tran 15m
TEXT -384 256 Bottom 2 !K3 T3a T3b T3c 1.
TEXT 392 864 Bottom 2 !K1 T1a T1b T1c 1.
TEXT -704 232 Bottom 2 !K2 T2a T2b T2c 1.
TEXT -24 216 Bottom 2 ;Old Fashioned Electrometer Using Parametric up Conversion\nThese days you should just use a AD549
TEXT -536 1368 Center 2 ;1nA full scale
TEXT -768 1640 Center 2 ;1A full scale
TEXT -776 1864 Center 2 ;100A full scale
TEXT 1088 816 Left 2 ;Add for 1A full scale
TEXT -536 1816 Center 2 ;10A full scale
TEXT 1088 624 Left 2 ;Add for 100A, 1mA full scale
TEXT -776 1192 Center 2 ;100pA full scale
TEXT 1088 896 Left 2 ;100pA, 1nA, 10nA, 100nA full scale
TEXT -768 1416 Center 2 ;10nA full scale
TEXT -536 1592 Center 2 ;100nA full scale
TEXT 1088 720 Left 2 ;Add for 10A full scale
TEXT -536 2040 Center 2 ;1mA full scale
TEXT -216 1544 Left 2 ;A 1% mismatch in J1, J2, J3, J4 capacitiances give a 6mV input offset and a 425mV output offset(4.25pA readout error) at 100pA full scale range.\nQ1, Q2, Q3, Q4 require a low drive impedance lest the gain of the loop inverts at high input currents.
TEXT 1184 1008 Bottom 2 ;10V full scale
TEXT 976 1120 Top 2 ;Trim to reduce\nerror to a\nfraction of 1pA