Variable Pressure Detector
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Transcript of Variable Pressure Detector
Variable Pressure Detector ECET 270
Andy Schnobrich
Overview This project utilizes a variable
capacitor as a pressure switch. The analog portion of the circuit is used to detect how much the switch is depressed. The digital portion of the circuit is used to Display the time that the switch is depressed and to display the current pressure level.
The Wien-Bridge Oscillator
+15V
15V
741
2
3
7
4
6
500
4.7k
RB
10k
R2
12.1k R1
12.1k
C2
.0022FC1
.0022F
RA
VOUT
The Peak Detector and Voltage Comparator Circuit
+15V
15V
741
2
3
7
4
6
Vin
(13.90°)[email protected]
D1
1N914
C1
.47FR1
10k
IDC
+15V
15V
741
2
3
7
4
6
R1
150k
R2
150k R3
680
VLED
VCC
ILEDV3
V1
The RC Wheatstone Bridge and The Instrumentation Amplifier
+15V
15V
741
2
3
7
4
6
C1
70pF
R1
56kR2
100k
C2
60.5pF
FROM THE WEIN BRIDGEOSCILLATOR
VOUT2VOUT1
+15V
15V
741
2
3
7
4
6
+15V
15V
741
2
3
7
4
6
+15V
15V
741
2
3
7
4
6
R2
12.1k
R1
10k
VOUT1
VOUT2
Vy
Vx
VOUT1
VOUT2
VOUT
R2
12.1k
R2
12.1kR2
12.1k
R2
12.1k
R2
12.1k
The Second Order Active Band Pass Filter
+15V
15V
741
2
3
7
4
6
+15V
15V
741
2
3
7
4
6
R1
12.1k
RA
12k 33k
C1
0.0033F
C2
0.0033F
R2
12.1k
R3
12.1k
FROMINSTRUMENTATION
AMPLIFIER
VOUT
330
RB
250 2250 4250 6250 8250 1025002468
1012141618
Frequency Response
frequency (Hz)
Vout
_pp
(V)
The Active Rectifier Circuit
+15V
15V
741
2
3
7
4
6
+15V
15V
741
2
3
7
4
6D1
1N914
D2
1N914
R2
12.1kR1
12.1k
R3
12.1kR5
12k+15V
15V
741
2
3
7
4
6
VOUT
VIN
R4
10k
The Active Peak Detector and Voltage Comparator Circuits
+15V
15V
741
2
3
7
4
6
+15V
15V
741
2
3
7
4
6
+15V
15V
741
2
3
7
4
6
R3
100k
R2
100k
R1
100k
R6
680
R5
680
R4
680
LED3
RED
LED2
YELLOW
LED1
GREEN
VOUT1
VREF1
3.9V
15mA
VREF2
6.3V
VREF3
10.2V
VOUT2
VOUT3
VOUT4
15V
15V
15V
15mA
15mA
The Transistor Drivers, and Passive Low Pass Filters
R3
100k?
R2
100k?
R1
100k?
VREF1
VREF2
VREF3
VOUT2
15V
15V
15V
R5
680
2N3903
RC2
1k
5V
C2
22F
VOUT5
VOUT1
R4
680
2N3903
RC1
1k
5V
C1
22F
VOUT4
VOUT3
R6
680
2N3903
RC3
1k
5V
C3
22F
VOUT6
FROM ACTIVE PEAK DETECTOR
RB2
22k
RB1
22k
RB3
1k
Normal1st Level
2nd Level
3rd Level
0V
0V
0V
0V
FROM ACTIVEPEAK DETECTOR
VOUT1
VOUT2
VOUT3
-13V
-13V
-13V
+13V
+13V
+13V
0VVOUT6
0VVOUT5
0VVOUT4
+5V
+5V
+5V
The Monostable Multivibrator, and 555 Square Wave Oscilator Circuits
VOUT4
Q4: 2N3904
5V
SN74121
2
3
4
5
6
7
14
13
12
11
10
9
8
1
5V
NC NC
NC
NC
NC
NC
OUTPUT
RB4
6.8k
RC4
1k
Cext
0.1F
RT
150k
VOUT7
1
3
2
4 8
7
6
5
RB
1M
RA
100k
C1
0.068FC2
0.01FOUTPUT
+5V
LM555
The Counter, Decoder, and Display Circuits
74190
FROM 555 TIMER
FROM 1/3 PRESSURETRANSISTOR SWITCH
FROM MONOSTABLEMULTIVIBRATOR
74190
74190
7446
a
b
c
d
e
f
d
R1
220
R7
220
.
.
.
.
7446
a
b
c
d
e
f
d
R8
220
R14
220
.
.
.
.
7446
a
b
c
d
e
f
d
R16
220
R22
220
.
.
.
.
R15
220
RCO
RCO
CLK
CLK
1/10's place
1's place
10's place
The Pressure Display Circuit
7
1
2
6
7446
8
16
vcc
13
12
11
10
9
15
14
a
b
c
d
e
f
g
R's220
.
.
.
.
R's220
a
b
c
d
e
f
20
10
7
8
9
19
18
17
16
vcc
.
.
.
.PLD
FULL
2/3
1/3
FROM TRANSISTORDRIVERS
MSB LSB