* 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
Q10 -V N031 N030 0 2N3906
C3 N020 N013 1000p IC=0
LT2a N007 IN 50
R5 N023 0 1K
R13 N036 IN 10Meg
R1 N002 0 500
D1 N019 N027 1N4148
R11 N021 N025 49.9
C13 N014 N013 .1 IC=0
LT1c N032 0 100
C20 0 N026 1n
C23 N004 0 500p
C6 N015 0 .01
R15 N038 IN 100K
LT3a N001 0 25
C2 0 N002 4n
J1 N007 N001 N007 2N5432
LT1b 0 N024 100
C9 N036 IN 2.5p
LT3c N002 0 25
Q9 +V N019 N021 0 2N3904
XU1 0 N013 +V -V OUT LT1001 ;pnba In+)In-)V+)V-)OUT
JQ4 N032 N006 0 2N4416
C16 IN 0 100p
LT2b IN N008 50
C12 N017 N013 .05 IC=0
R24 N004 N003 400
R6 N029 -V 4.75K
C1 N033 IN .015p
R22 N006 N005 100
C18 N035 IN .4p
C24 N003 0 250p
R18 N035 IN 100Meg
LT3b 0 N012 25
LT2c 0 N011 50
R8 +V N015 1.98K
C19 N039 IN 50p
C8 N026 P001 .1
R23 N005 N004 200
Q8 N019 N016 N015 0 2N3906
R10 +V N018 1.2K
D2 N027 N031 1N4148
C14 OUT IN .04p
R19 N039 IN 10K
JQ2 N032 N009 N028 2N4416
R16 OUT IN 10G
V1 +V 0 15
LT1a 0 N026 100
R7 +V N016 2.5K
R3 N033 IN 100G
C5 N029 0 .01
C7 0 N011 2n
V3 N010 0 pulse(-5 0 0 10n 10n .5u 1u)
Q7 N016 N023 N029 0 2N3904
C11 N038 IN 100p
K1 T1a T1b T1c 1.
C22 N005 0 1n
R20 N013 N028 100
R4 N022 -V 4.99K
R12 N025 N030 49.9
J3 N012 N007 N012 2N5432
JQ5 N018 0 N011 2N4416
JQ1 N024 N006 N028 2N4416
C4 N023 N022 .01
C10 N037 IN 75p
C17 N034 IN .2p
R9 N031 -V 4.22K
R14 N037 IN 1Meg
C15 OUT N013 25p IC=0
K3 T3a T3b T3c 1.
J4 N008 N012 N008 2N5432
R17 N034 IN 1G
V2 -V 0 -15
R21 P001 N025 500
K2 T2a T2b T2c 1.
C21 N013 0 .01
I1 0 IN PULSE(0 1000p 1m 1u 1u 5m 10m)
R2 N003 N002 25K
Q6 +V N018 N022 0 2N3904
JQ3 N024 N009 0 2N4416
J2 N001 N008 N001 2N5432
.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):
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WINDOW 0 1 37 Right 2
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SYMATTR Value 25
SYMATTR Type ind
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SYMATTR InstName R5
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SYMBOL res -624 576 R0
SYMATTR InstName R10
SYMATTR Value 1.2K
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SYMBOL res 448 288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R22
SYMATTR Value 100
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WINDOW 0 2 39 Right 2
WINDOW 3 2 74 Right 2
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SYMATTR Type ind
SYMBOL Opamps\\LT1001 992 944 R0
WINDOW 3 -40 153 Left 2
SYMATTR InstName U1
SYMBOL res 288 288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R23
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WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
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SYMATTR InstName V2
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SYMBOL cap -496 1408 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C14
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WINDOW 3 61 46 VCenter 2
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SYMATTR Value 2N5432
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WINDOW 3 61 34 Left 2
SYMATTR InstName Q10
SYMATTR Value 2N3906
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SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL cap -736 1568 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C9
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SYMATTR InstName R11
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SYMBOL cap -496 2080 R90
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WINDOW 3 32 32 VTop 2
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SYMATTR InstName R8
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SYMBOL cap -496 1632 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
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SYMATTR InstName R9
SYMATTR Value 4.22K
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WINDOW 3 61 46 VCenter 2
SYMATTR InstName J3
SYMATTR Value 2N5432
SYMBOL cap 944 880 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
WINDOW 123 60 32 VTop 2
SYMATTR InstName C15
SYMATTR Value 25p
SYMATTR Value2 IC=0
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WINDOW 3 32 32 VTop 2
SYMATTR InstName C6
SYMATTR Value .01
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SYMATTR Type ind
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WINDOW 3 32 32 VTop 2
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SYMATTR InstName C3
SYMATTR Value 1000p
SYMATTR Value2 IC=0
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WINDOW 3 32 32 VTop 2
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SYMATTR Value PULSE(0 1000p 1m 1u 1u 5m 10m)
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WINDOW 3 32 32 VTop 2
SYMATTR InstName C16
SYMATTR Value 100p
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SYMATTR Value 50
SYMATTR Type ind
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 100K
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 100G
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SYMATTR Value 1n
SYMBOL cap -496 1856 R90
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WINDOW 3 32 32 VTop 2
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WINDOW 3 32 56 VTop 2
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WINDOW 0 24 56 Left 2
WINDOW 3 24 8 Left 2
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WINDOW 0 0 72 Right 2
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SYMATTR InstName T1a
SYMATTR Value 100
SYMATTR Type ind
SYMBOL ind2 -432 368 R0
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SYMATTR Type ind
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WINDOW 3 58 23 Left 2
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SYMATTR Value 2N4416
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WINDOW 0 4 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 50
SYMATTR Type ind
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SYMATTR Value 2N5432
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WINDOW 3 61 34 Left 2
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SYMATTR InstName C21
SYMATTR Value .01
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WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
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SYMATTR Value .01
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WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 500
SYMBOL cap -736 1120 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value .015p
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SYMATTR InstName Q5
SYMATTR Value 2N4416
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WINDOW 3 -32 56 VBottom 2
SYMATTR InstName V3
SYMATTR Value pulse(-5 0 0 10n 10n .5u 1u)
SYMBOL cap -736 1792 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C11
SYMATTR Value 100p
SYMBOL cap 944 704 R90
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
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SYMATTR Value 15
SYMBOL res 864 976 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
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SYMATTR Value 100
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WINDOW 3 56 54 Left 2
WINDOW 0 56 24 Left 2
SYMATTR Value 2N4416
SYMATTR InstName Q1
SYMBOL res -32 928 R0
SYMATTR InstName R12
SYMATTR Value 49.9
SYMBOL cap -368 1056 R0
SYMATTR InstName C5
SYMATTR Value .01
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SYMATTR InstName R6
SYMATTR Value 4.75K
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SYMATTR InstName Q7
SYMATTR Value 2N3904
SYMBOL res -288 544 R0
SYMATTR InstName R7
SYMATTR Value 2.5K
SYMBOL diode -176 832 R0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL res -720 1456 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R17
SYMATTR Value 1G
SYMBOL res -32 288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 25K
SYMBOL njf 528 1104 R180
WINDOW 0 39 90 Right 2
WINDOW 3 35 7 Right 2
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SYMATTR Value 2N4416
SYMBOL ind2 400 976 R180
WINDOW 0 1 71 Right 2
WINDOW 3 2 37 Right 2
SYMATTR InstName T1b
SYMATTR Value 100
SYMATTR Type ind
SYMBOL res -480 1968 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R19
SYMATTR Value 10K
SYMBOL njf -512 464 M270
WINDOW 0 34 48 VCenter 2
WINDOW 3 61 46 VCenter 2
SYMATTR InstName J4
SYMATTR Value 2N5432
SYMBOL npn -576 720 R0
SYMATTR InstName Q6
SYMATTR Value 2N3904
SYMBOL res -720 1680 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 10Meg
SYMBOL res 128 288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R24
SYMATTR Value 400
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