Capacitance Water Level Sensor

+5V

+5V

+5V

+5V +12V

470K

S 4013B

4 4.7M

27pF

PN2222

OSCILLATOR

Q

100K

32KHz CLOCK

2

2V

1K

R CK

100pF

3K

6

32.768KHz

100K

ZERO ADJ D

0.1 2K

3

+

0V - 2.8V

SPAN ADJ

5

BUFFER

FUEL GAUGE

1M

GND

OUT

LAMP

0 - 100%

2V - 3.4V IN

+ -

5mA

AVERAGING

0.47uF +5V

CIRCUIT

TOP VIEW SWITCHED +12V

78L05

30K

+5V

3V

+5V +

10uF

+

10uF

0.1

20K

9

+12V ON WHEN IGNITION ON

D 32KHz CLOCK

11

CLK

Q

13

Q

R

10K

DG S

4013B

10

75K

4.7K

12

S

+ 3V BNC CONNECTOR

D

8

CAPACITANCE PROBE LIQUID LEVEL CHANGES C A P ACITANCE BETWEEN TUBES

RG58 COAX

G BS170

CAPACITANCE PROBE S

CAPACITANCE TO

0.01 Cx

DUTY CYCLE CONVERTER

100pF - 170pF

DRAWN BY: DAVE JOHNSON

LIQUID FUEL GAUGE

CAPACITANCE PROBE CIRCUIT

DAVID JOHNSON AND ASSOCIATES C A P A C I TANCE TYPE LNG FUEL GAGE SENSOR Size

Document Number

Date:

Tuesday, June 13, 2000

B

Rev

CAPGAGE.DSN Sheet

A

1

of

1