capmeter1c
TRANSCRIPT
+- 1
2
34.5V
8
4
OUTPUT
4
21
3+-
8
+-
5
76
4.5V
+9V
+9V
20KHz
TRIANGLE SIGNAL GENERATOR
CURRENT TOVOLTSCONVERTER
POSITIVE PEAKDETECTOR
RIPPLE FILTER
5VPP
25uS
dV/dT = 5v/25uS = 200,000v/sec
POSITION CLOSETO Cx CAP
POLY CARB CAP
OR NPO CERAMIC
2V PP FOR 10pF
DRAWN BY: DAVE JOHNSON
LF412
A1A
A2A
A2B
LF412
LF412
4.5V
+9V
SELECT VALUE FOR2VPP AT 10pF Cx
INGND
OUT
78L09
12V +9V
+4
2
3
8- 1LMC6482
+
4
2
38
-1
X2.5AMP
LMC6482
A3A
+9V
+9V
7
-
5
6
+GROUNDREFERENCEDSIGNAL
0V = 0pF
X2+5V @ 10pF
LM6482
A3B
A4A
IN GND OUT
TOP VIEW
+9V
ADJUST FOR ZEROVOLTS AT FINALOUTPUT WITH MINIMUMCAPACITANCE
7.8V
5.5V AT 10pF
ADJUST FOR 5 VOLTSAT FINAL OUTPUTWITH MAXIMUMCAPACITANCE
+9V
-
8+LM311
4 A1A
3
27
+9V+9V
+9V
20KHz
+9V
DAVID JOHNSON AND ASSOCIATES
0pF - 10pF
LOW VALUE CAPACITANCE METER
CAPACITANCECHANGE
CAPMETER1C.DSN A
LOW VALUE CAPACITANCE METER
B
1 1Sunday, December 12, 2004
Title
Size Document Number Rev
Date: Sheet of
+TANT4.7uF
0.1uF
0.1uF
10K
10K
0.47uF
200K
+TANT4.7uF
10K
220K
0.1uF
7.5K
200K
0.01uF 1M
150K
220K
0.1uF
0.047uF
10.0K1%
0.1
U?C
4071B8
910
U?D
4071B12
1311
U?B
4071B5
64
U?A
4071B1
23
680
0.1uF10K
1K1%
10K1%
3.9pF
ZERO ADJ
2K
4.02K1%
CX
10.0K
1%
4148
SPAN ADJ
5K
0.1uF
0.0015uF
10K1%
10K
0.1uF
0.1uF
CxTO Cx
TO Cx Cx