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Technical Description
Gasman II Portable Gas Detector
Crowcon Detection Instruments Limited
2 Blacklands Way
Abingdon Business Park
Abingdon
Oxfordshire
OX14 1DY
United Kingdom
Contents
Contents Page 1
Functional Description Page 2
- System Overview
Page 2
- Gasman II Block Diagram
Page 2
- Gasman II Circuit Description
Page 3
Appendix A - Schematic Diagram (Sheet1) Page 5
Appendix A - Schematic Diagram (Sheet2) - Toxic Page 6
Appendix A - Schematic Diagram (Sheet2) - Flammable Page 7
Appendix A - Schematic Diagram (Sheet2) - Oxygen Page 8
Appendix A - Schematic Diagram (Sheet3) Page 9
Appendix A - Schematic Diagram (Sheet4) Page 10
Appendix B - Parts List (Sheet 1) Page 11
Appendix B - Parts List (Sheet 2) - Toxic Page 12
Appendix B - Parts List (Sheet 2) - Flammable Page 13
Appendix B - Parts List (Sheet 2) - Oxygen Page 15
Appendix B - Parts List (Sheet 3) Page 16
Appendix B - Parts List (Sheet 4) Page 17
1
Functional Description
System Overview
The GasmanII Portable Gas Detector system is designed to detect the presence of toxic or flammable gases or the
absence of life supporting gases. As an option it may be fitted with a low power transmitter PCB to permit the use of a
body-worn Vibrating Pager Unit.
The standard GasmanII Portable Gas Detector monitors the level of a particular gas in the atmosphere and provides both
an audible and a visual alarm should the gas levels become unacceptable. When fitted with the optional low power
transmitter PCB the unit also emits a 418MHz RF carrier wave that is 'On-Off-Key' (OOK) modulated at about 10Hz. It is
this signal, which is only emitted while the alarm condition exists, that the GasmanII Vibrating Pager Unit intercepts and
produce a pulsing vibration to augment the audible and visual alarms provided by the GasmanII Portable Gas Detector.
Gasman II Block Diagram
The circuit consists of the functional blocks as shown in Figure 1 below and a complete unit is assembled from 3 PCBs,
with an optional fourth PCB, as shown in the appendices. Each of the three distinct gas types requires a specific type of
gas sensor, signal conditioning circuitry and calibration information. All of the gas sensors share a similar mechanical
design and are plugged into a small daughter board at the top of the unit. The output signal from the various types of
sensor is different and each requires a corresponding signal conditioning amplifier to interface the signal to the common
CPU section. The calibration information is stored in non-volatile memory within the unit and is factory set.
The CPU is powered in a low-power state at all times that batteries are present and controls the electronic switch to apply
power to the rest of the circuitry when one of the front-panel mounted buttons is pressed. Once powered the unit
continuously monitors the gas level comparing it with preset alarm levels and, should an alarm level be exceeded, the
buzzer and the LED operate to provide both audible and visual warnings. The two signals that drive the LEDs are
combined on the optional low-power transmitter PCB to form a 10Hz signal that is used to modulate an RF Monolithics
transmitter module.
Figure 1: Gasman II Block Diagram
cpu
(ROM & RAM)
gas
sensor
LCD display
buzzer
LEDs
analogue
signal conditioning
electronic
switch
low
power
txmtr
(optional)
2
Gasman II Circuit Description
The following description of the circuit refers to the schematics shown in Appendix A.
Sheet 1 (CPU/Display PCB)
The CPU is at the heart of the unit and contains the operating program stored in OTPROM and a quantity of RAM for
general variable storage. Q1A and IC3 provide the electronic switch shown in the Block Diagram above and these two
components form a switched +3V supply that is used to power various circuit sections. IC2 is an EEPROM and is used to
store data relating to configuration and calibration while IC4 provides a CPU reset/watchdog function. Under the control of
one of the CPU I/O lines Q1B is used to switch the LCD backlight on and off. S1 and S2, the two user push-buttons, are
used to control the units function. Two crystals, X1 and X2, provide the clock signal for the CPU with X1, at 2.51MHz,
providing the frequency for normal operation and X2, at approximately 32kHz, providing the clock signal for the CPU when
not in full operation. The connections to the Main PCB are made through connectors J1 and J2 with JP4 providing the
connection to the optional low-power transmitter PCB.
Sheet 2 (Main PCB) - Toxic
This PCB contains the 3 batteries used to provide power to the unit, the analogue signal conditioning for the gas sensor
and also the 'buffers' for driving the buzzer and the LEDs.
IC2 provides the necessary amplification and level shifting to enable the output from the gas sensor to be coupled to the
CPU ADC input. The unit is configured using a custom PC application and communication is accomplished via connector
J4. IC3 (comparator) is used to extract the data sent by the PC from the common 'signal' wire and Q2 is used to impress
the data sent by the Gasman II to the PC onto the 'signal' wire. Varistor, RV1, provides protection against ESD transients.
IC3 (op-amp) provides a control loop for powering the sensor and is arranged to maintain constant operating conditions.
Header, H1, is a small plug-in PCB containing resistors that set the offset and gain of the sensor signal conditioning
amplifier. IC1(A/B) is used to provide a boosted drive signal during an alarm condition for the buzzer and two LEDs. IC1B
is wired to provide a differential drive to the buzzer and thus generates a greater sound level. IC1A provides the drive to
the LEDs and also the drive to Q2 as mentioned above. Q1 is a depletion-mode FET, i.e. its channel conducts until biased
off, which is used to short the sensor terminals when the unit is switched off. The connections to the CPU/Display PCB
are made through connectors J1 and J2 while J3 provides the connection to the Sensor PCB.
Sheet 2 (Main PCB) - Flammable
This PCB contains the 3 batteries, NiCAD types, used to provide power to the unit, the analogue signal conditioning for
the gas sensor and also the 'buffers' for driving the buzzer and the LEDs. An additional function fitted to the PCB is the
ability to charge the NiCAD batteries.
IC5 and IC2 provide the necessary amplification and level shifting to enable the output from the gas sensor to be coupled
to the CPU ADC input. The CPU provides a method of 'auto-zeroing' the output from the sensor by providing a variable
M/S ratio PWM signal to the base of Q3. The effect of this, once smoothed by R4 and C5, is to provide a variable
'calibration voltage' at TP3. FET, Q4, is used to change the gain of the signal-conditioning amplifier under CPU control.
The unit is configured using a custom PC application and communication is accomplished via connector J4 and varistor,
RV1, provides protection against ESD transients. IC3 in conjunction with FET, Q1, provide a low battery protection system
and remove power to the PCB when the battery voltage falls below about 2.3V. IC4, in conjunction with FET, Q2, provide
a power supply to the sensor that may be turned off by the CPU to save battery power. IC1(A/B) is used to provide a
boosted drive signal during an alarm condition for the buzzer and two LEDs. IC1B is wired to provide a differential drive to
the buzzer and thus generates a greater sound level. IC1A provides the drive to the LEDs and also provides the transmit-
data signal to the PC over the communications link. The connections to the CPU/Display PCB are made through
connectors J1 and J2 while J3 provides the connection to the Sensor PCB.
Sheet 2 (Main PCB) - Oxygen
This PCB contains the 3 batteries used to provide power to the unit, the analogue signal conditioning for the gas sensor
and also the 'buffers' for driving the buzzer and the LEDs. An additional function is the provision of an NTC thermistor to
permit the ambient temperature to be monitored.
IC2 provides the necessary amplification and level shifting to enable the output from the gas sensor to be coupled to the
CPU ADC input. The unit is configured using a custom PC application and communication is accomplished via connector
J4. IC3 is used to extract the data sent by the PC from the common 'signal' wire and Q2 is used to impress the data sent
by the Gasman II to the PC onto the 'signal' wire. Varistor, VR2, provides protection against ESD transients. IC1(A/B) is
used to provide a boosted drive signal during an alarm condition for the buzzer and two LEDs. IC1B is wired to provide a
differential drive to the buzzer and thus generates a greater sound level. IC1A provides the drive to the LEDs and also the
drive to Q2 as mentioned above. Q1A and TH1 provide the ambient temperature monitoring capability with the voltage
across the thermistor being fed to a CPU ADC input. The connections to the CPU/Display PCB are made through
connectors J1 and J2 while J3 provides the connection to the Sensor PCB.
3
Sheet 3 (Sensor PCB)
This is a simple PCB that plugs into the Main PCB via connector J1. It contains the buzzer and the two LEDs along with
two sites for a gas sensor. The two sites are necessary to accommodate the two slightly different physical shapes of the
gas sensors and are overlaid so as to position each of the gas sensor types in the same place when fitted.
Sheet 4 (Optional Low-Power Transmitter PCB)
This simple PCB plugs into the CPU/Display PCB via J1 which carries both power and the two LED control signals. The
LED control signals are 'ORed' together on this PCB to provide a 10Hz modulation waveform. This waveform is used to
power the transmitter module, IC1, using FETs Q1 and Q2.
4
Appendix A - Schematic Diagram (Sheet 1)
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Date: December 19, 1999 Sheet 1 of 1
Size Document Number REV
C 2648-CD 1V1
Title
GASMAN 2 CPU (DISPLAY) BOARD
Crowcon Ltd
WITHOUT REFERENCE TO CERTIFYING AUTHORITY -
Any resistor may be substituted by an
alternative whose resistance is greater, or >=1k.
Any capacitor may be substituted by an
alternative whose capacitance is lower.
R15
3k9
Vdig
SensorSleep
SparePort1
SparePort2
SparePort3
/PotDrive
Vdig
/Alarm-LED-1
/Alarm-LED-2
SensorSignal2
1
2
3
4
5
6
7
8
9
10
11
J2
R1
3k9
1
6
5 Q1A
IMT1
3V
TxD
RxD
PWM
Potentiometer
sound
/SounderOn
SensorSignal1
1
2
3
4
5
6
7
8
9
10
11
J1
3V reference
1
TP3
C1
10uF
/SwitchDrive
TxD
RxD
VdigSwitched
3V
1 2
3
IC3
TC55
SensorSignal1
C2
10uF
TXD
90
RXD
89
X
1
8
X
2
7
V
C
C
7
9
V
C
C
3
4
C
O
M
4
3
5
C
O
M
3
3
6
C
O
M
2
3
7
C
O
M
1
3
8
A
V
S
S
5
G
N
D
9
G
N
D
3
0
SEG1
39
P5-1
40
P2-5
19
P5-2
41
P5-3
42
P5-4
43
P5-5
44
P5-6
45
WKP7/P5-7
46
P6-0
47
P6-1
48
P6-2
49
P6-3
50
P6-4
51
P6-5
52
P6-6
53
P6-7
54
P7-0
55
P7-1
56
P7-2
57
P7-3
58
P7-4
59
P7-5
60
P7-6
61
P7-7
62
P8-0
63
P8-1
64
P8-2
65
P8-3
66
P8-4
67
P8-5
68
P8-6
69
P8-7
70
P9-0
71
P9-1
72
P9-2
73
P9-3
74
P9-4
75
P9-5
76
P9-6
77
SEG40/P9-7
78
M
D
0
1
3
P2-7
21
PB7/AN7
100
PB6/AN6
99
PB5/AN5
98
PB4/AN4
97
P4-3/IRQ0
91
AVCC
92
AN0
93
P3-0/SCK1
22
P3-1/SI1
23
P3-2/SO1
24
P1-7
87
P1-6
86
P1-5
85
P1-4/PWM
84
P1-3
83
P1-2/TMOFH
82
P1-1
81
P1-0
80
P3-6
28
P3-5
27
P3-4
26
P3-3
25
P2-4
18
P2-6
20
P2-0
14
P2-1
15
P2-2
16
P2-3
17
P4-0
88
V
3
3
1
V
2
3
2
V
1
3
3
/RES
12
O
S
C
1
1
0
O
S
C
2
1
1
AN11
4
AN10
3
AN9
2
AN8
1
AN3
96
AN2
95
AN1
94
P3-7
29
TEST
6
IC1
H8/3834
R2
3k9
C4
1uF
C5
100nF
1
TP4
C3
10nF
R10
100k
S8
S7
S6
S5
S4
S3
S1
S2
1g
1f
1a
1b
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
J3
LCD CONNEXION 2x16
S2
S1
3a
3b
3c
3d
3e
3f
3g
DPT1
2a
2b
2c
2d
2e
2f
2g
DPT2
1a
DPT1
2g
2f
2a
2b
DPT2
3g
3f
3a
3b
COMMON
3c
S8
3d
S7
3e
2c
S6
2d
Potentiometer
SensorSignal2
1
TP5
SCK
DATA
R16
10k
R17
10k
VCC
8
WP
7
A0
1
CLK
6
DATA
5
/A1
2
GND
4
A2
3
IC2
24C16
R19a
0R
R19b
0R
VdigSwitched
Vdig
2k x 8
EEROM
3V
1
TP6
1b
1c
1d
1e
1f
1g
S5
2e
S4
1c
1d
1e
S3
BatteryState
/PotDrive
1
TP7
1
TP8
1
TP9
BatCheck
R3
3k9
VdigSwitched
R4
3k9
1
TP11
SCK
SensorSleep
SparePort1
SparePort2
Vdig
R14
1k
Always Low for Gasman II
R20
1k
Connections to optional daughter board:
R8
3k9
S1
R9
3k9
1
TP15
1
TP16
S2
D1
GF1J
D2
GF1J
sound
PWM
SparePort3
/SounderOn
/Alarm-LED-1
/Alarm-LED-2
Vdig
R7
27k
C9
1uF
1
TP14
D3
1SS355
Vdig
-25-CYT
WDI
4
/RESET
1
/MR
3
VCC
5
GND
2
IC4
MAX6316
C6
100nF
R18
100R
R13
3k9
D3a D3b
Backlights
1
TP13
Vdig
R5
150R
R6
150R
4
3
2 Q1B
IMT1
1
TP1
Force Reset
by shorting
across C9
X2
32.768kHz
R11
1M
1 3
2
X1 2.51 MHz
C8
15pF
C7
15pF
Vdigswitched
/Alarm-LED-1
/Alarm-LED-2
Radio transmitter for optional Vibrator
1
2
3
4
JP4
TC55
3V reg
outingnd
1 5
MAX
6316
R12
10k
PCB issue: 1V1
PCB No: PC2065 issue 1V1
Filename: G2-CPU2
Appendix A - Schematic Diagram (Sheet 2) - Toxic
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Date: December 20, 1999 Sheet 1 of 1
Size Document Number REV
B 2646-CD-PROD 2v0
Title
GASMAN 2 TOXIC BOARD
v0
Crowcon Ltd
right
angled
board
1
J3-9
1
J3-4
1
TP1
1
TP2
Sounder+
Sounder-
R11
1M
sound
Speaker Drive
A1
11
A2
13
A3
15
A4
17
/OE
19
Y1
9
Y2
7
Y3
5
Y4
3
IC1B
74HC240
VCC
GND
Vdig
C10
10uF
C16
100nF
VR1
10k
3V
GND
RxD
TxD
Potentiometer
sound
/SounderOn
SensorSignal1
1
2
3
4
5
6
7
8
9
10
11
J1
PWM
To CPU board
/PotDrive
/Alarm-LED-1
/Alarm-LED-2
1
2
3
4
5
6
7
8
9
10
11
J2
SparePort1
SparePort2
Cal / Zero pot
E03556
R23
10k
R23 allows s/w to tell
this is an issue 2 PCB
1
2
J3X
TEST JIG
Sounder-
R14
1M
R15 10k
/SounderOn
/Alarm-LED-1
/Alarm-LED-2
A1
2
A2
4
A3
6
A4
8
/OE
1
Y1
18
Y2
16
Y3
14
Y4
12
IC1A
74HC240
TxD
Vdig
/TxD
R32
150R
R31
150R
1
TP3
1
TP4
1
2
3
Q1
J177
1
TP21
Counter
Ref
Sense
1
J3-2
1
J3-6
1
J3-5
1
J3-7
1
J3-3
1
J3-8
1
TP5
1
TP6
"S7"
J177 (top view)
12
3
DS
G
Comms
Counter
1
TP7
R3
3k9
Short during Reset
to re-initialise s/w
RxD
The link between
SparePort 1 & 2
this is a Toxic board.
enables the s/w to tell
1
TP9
Vdig
VdigSwitched
GND
SensorSignal2
/SensorSleep
Vdig
D2
1SS355
1
TP16
1
TP17
R12
10k 1
2
3
4 8
6
5
7
IC3
MAX951
R1
3k9
C14
1nF
C15
1nF
1
TP8
1
TP10
1
2
3
(Sensor is
on other PCB)
Ref
R13
1
4
3
7
5
8
2
6
H1
HEADER
Sense
/SensorSleep
C2
100pF
1
TP12
R8
4k7
C17
100pF
1
TP14
1
TP15
VdigFilt
C4
10nF
SensorSignal1
C7
100pF
R7
10k
2
3
6
4
8
5
71
IC2
LTC1152
C8
100pF
R10 4k7
1
TP13
R5
100k
R6 100k
C9
100pF
C5
1nF
3V
C11
10nF
C12
1nF
C13
1nF
R2
3k9
1V2
1
TP11
R24
R
R25
R
C18
100nF
spare comparator
Vdig
1V2
VdigFilt 1
2
3
FLT1
1
2
J4
1.5mm segregation
RV1
VARISTOR
*
**
R20 >=200R
*
0W4
D3
6V2
D4
6V2
R9
1k
Q2
BC849
R4
10k
1
TP18
1
TP19
1
TP20
/TxD
*
changed without reference to DEMKO A/S
This component / distance must not be
WITHOUT REFERENCE TO CERTIFYING AUTHORITY -
Any resistor may be substituted by an
alternative whose resistance is greater, or >=1k.
Any capacitor may be substituted by an
alternative whose capacitance is lower.
Vdig
C3
10nF
C6
10uF
"2C"
C
BE
BC849
*
F1
125mA C1
10uF
1
2
B1
4.5V
1
2
B2
1
2
B3
3 alkaline cells PCB No: PC2069
Filename: G2-Tox2
PCB Issue: 2v0
Appendix A - Schematic Diagram (Sheet 2) - Flammable
7
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Date: December 20, 1999 Sheet 1 of 1
Size Document Number REV
B 2V1
Title
GASMAN 2 FLAMMABLE BOARD
Crowcon Ltd
1
J3-9
1
J3-4
right
angled
board
1
TP21
1
TP22
Sounder+
Sounder-
R22
1M
sound
Speaker Drive
VCC
GND
A1
11
A2
13
A3
15
A4
17
/OE
19
Y1
9
Y2
7
Y3
5
Y4
3
IC1B
74HC240
1
TP19
Vdig
3Vswitched
C10
100nF
C9
100nF
C2
10uF
C4
10uF
Vdig
VIN
1
GND
2
/SHDN
3
BP
4
OUT
5
IC4
MAX8878
R19
R
1
TP1
Pellistor power supply
3V
GND
RxD
TxD
Potentiometer
sound
/SounderOn
SensorSignal1
PWM
1
2
3
4
5
6
7
8
9
10
11
J1
RESET
To CPU board
/PotDrive
SparePort2
/Alarm-LED-1
/Alarm-LED-2
1
2
3
4
5
6
7
8
9
10
11
J2
SparePort1 HI to boost gain
SparePort4
Cal / Zero pot
VR1
10k
R23
10k
SparePort3 1 2
3
Q2
BSS123
D1
1SS355
R18
R
1
TP2
C11
10nF
/SounderOn
/Alarm-LED-1
/Alarm-LED-2
A1
2
A2
4
A3
6
A4
8
/OE
1
Y1
18
Y2
16
Y3
14
Y4
12
IC1A
74HC240
TxD
1
TP13
R32
150R
R31
150R
1
TP20
1
J3-7
1
J3-3
1
J3-8
1
TP10
1
TP12
1
J3-1
1
J3-2
FlamBridge
3Vswitched
C3
1nF
1
TP8
1
TP9
Comms
BoostedTxD
D2
1SS355
Vdig
VdigSwitched
GND
SparePort3
BatTypeSense
SensorSignal2
J2-8, J2-9 are connected to help CPU tell it’s
connected to a Flammable PCB.
R23 tells processor this is an issue 2 PCB.
D4
<=6V2
D3
<=6V2
MMST2222A
c
be
1
TP14
"RIP"
1
TP15
R3
10k
R4
10k
FlamBridge
R5
10k
R7
1M
1
TP16
Vdigswitched
3
4
2
1
5
IC5
MAX4040
R16
82k
R15
82k
1
TP7
1
2
34
5
MAX4040
top view
R9
3k9
1
TP17
1
TP18
R17 1M
C7
1nF
FlamRef
1
TP3
R6
11k
C5
2u2
PWM
R2
4k3
Q3
MMST2222A(9.6kHz)
1
TP23
*
R20
>=200R
*
1.5mm Segregation
1
2
J4
RV1
D7
>=750mA
D8
>=750mA
K
D7,D8
1
TP5
*
*
R27
10R
0W4
gs
d
BSS123
R10
10k
R12
4k7
SA
SensorSignal1
C6
10nF
1
TP4
1
TP6
3
4
2
1
5
IC2
MAX4040
R13
10k
Vdigswitched
typ. marking:
"ACGF"
changed without reference to DEMKO A/S
This component / distance must not be
*
WITHOUT REFERENCE TO CERTIFYING AUTHORITY -
Any resistor may be substituted by an
R14
10k
Vdig
6 ohms
N-channel
R8
R
R11
0R
1 2
3
Q4
BSS123
SparePort1
D10
R1
0R
4
3 1
2
5
Q1
NDC632P
Vin
1 2
LK2
RESET
C1
1uF
R24
>=100R
G
N
D
1
V
I
N
3
RESET
2
IC3
MAX6327
F1
125mA
*
*
D6
<=6V2
D5
<=6V2
D9
GF1J
1
2
B1
1
2
LK1
ANC
"ZS7"
1
2
B2
1
2
B3
Charging circuitry
R21
1k
BatTypeSense
d
s
s
d
d
g
NDC
632P
61
p-channel
PCB No: PC2067 issue 2v1
Filename: G2FlamV2
Any capacitor may be substituted by an
alternative whose capacitance is lower.
alternative whose resistance is greater, or >=100R.
Appendix A - Schematic Diagram (Sheet 2) - Oxygen
58
8 7 6 5 4 3 2 1
A
B
C
D
12345678
D
C
B
A
Date: December 19, 1999 Sheet 1 of 1
Size Document Number REV
B 2645-CD 2v0
Title
GASMAN 2 OXYGEN BOARD
Crowcon Ltd
1
J3-9
1
J3-4
1
TP1
1
TP2
Sounder+
Sounder-
R12
1M
sound
Speaker Drive
A1
11
A2
13
A3
15
A4
17
/OE
19
Y1
9
Y2
7
Y3
5
Y4
3
IC1B
74HC240
VCC
GND
Vdig
C10
10uF
C4
100nF
R8
10k
1
TP13
Temperature sensor
SparePort1
3V
R9
10k
1
6
5
Q1A
IMT1
1
TP14
VR1 10k
1 2
J3
short during
Reset to
re-initialise
software
"TEST JIG:"
3V
GND
RxD
TxD
Potentiometer
sound
/SounderOn
SensorSignal1
1
2
3
4
5
6
7
8
9
10
11
J1
To CPU board
/PotDrive
/Alarm-LED-1
/Alarm-LED-2
SparePort1
1
2
3
4
5
6
7
8
9
10
11
J2
SparePort2
Cal / Zero pot
is an issue
2v0 board
R23 permits s/w
to tell this
R23
10k
Temp
C19
1nF
1
2
TH1
NTC
10k at 25C
/SounderOn
/Alarm-LED-1
/Alarm-LED-2
A1
2
A2
4
A3
6
A4
8
/OE
1
Y1
18
Y2
16
Y3
14
Y4
12
IC1A
74HC240
TxD
R31
R
R32
R
1
TP5
1
TP6
1
J3-7
1
J3-3
1
TP3
1
TP4
1
J3-5
1
J3-8
1
J3-6
OxySignal
Comms
R1
270k
1
TP9
1
2
J5
1
TP12
Linking SparePort 1 & 2
allows s/w to tell this
is an Oxygen board
Vdig
VdigSwitched
GND
Temp
SparePort3
1
TP16
1
2
3
4 8
6
5
7
IC3
MAX951
1
TP22
Double
gain
R5
2k7
1
TP15
R3
2k7
1
TP10
1
TP11
C3
10nF
R2 1k
C9
1nF
2
6
3
4
7
IC2
OP191
R18
2k7
1
TP7
1
TP8
3V 1
2
3
FLT1
SensorSignal1
R11
100R C5
10nF
R6
2k7
OxySignal
*
D4
6V2
Vdig
1
TP17
1V2
Vdig
RxD
1V2
R10
10k
1
2
J4
1.5mm segregation
VR2
VARISTOR
*
R20
>=200R
*
*
D3
6V2
R7
3k9
1
TP18
D1
1SS355
/TxD
R4
10k
1
TP19
1
TP20
Q2
BC849
1
TP21
This component / distance must not be
WITHOUT REFERENCE TO CERTIFYING AUTHORITY -
Any resistor may be substituted by an
alternative whose resistance is greater, or >=1k.
Any capacitor may be substituted by an
alternative whose capacitance is lower.
"2C"
C
BC849
Vdig
C1
10uF
F1
125mA
*
C2
10uF
0W4
1
2
B1
4.5V
1
2
B2
1
2
B3
3 alkaline cells
Note:
one half of
Q1 is spare.
IMT1 dual PNP xistor
c b e(6)
c(1)be
(symmetrical)
BE
*
PCB issue: 2v0
PCB No: PC2068
Filename: G2-ox2
changed without reference to DEMKO A/S
Appendix A - Schematic Diagram (Sheet 3)
9
8 7 6 5 4 3 2 1
A
B
C
D
12345678
D
C
B
A
Date: December 19, 1999 Sheet 1 of 1
Size Document Number REV
AA
Title
Gasman 2 Sensor Board Issue V4
Crowcon Ltd
1
J1-9
Sounder+
R2
43R
R1
>10R
C1
1nF
1
2
3
S1
Toxic
LS1
AT-01
1.5mm SEGREGATION
Sounder-
Counter
1
J1-4
1
J1-5
1
J1-2
1
J1-1
1
J1-6
3V
Sense
Ref/Bridge
1
2
3
S2
Flam
sensor
sensor
D1
LED
D2
LED
S1 and S2 are overlaid
because only 1 is
fitted at a time.
Alarm-LED-1
Alarm-LED-2
1
J1-8
1
J1-7
1
J1-3
GND
Filename: G2-sens
PCB no: PC2066(bottom view)
Toxic / Oxygen sensor
(bottom view)
Flammable sensor
2
1
3
3
21
1 = Counter
2 = Ref
3 = Sense
TOXIC:
Appendix A - Schematic Diagram (Sheet 4)
10
8 7 6 5 4 3 2 1
A
B
C
D
12345678
D
C
B
A
Date: December 19, 1999 Sheet 1 of 1
Size Document Number REV
A 1.0
Title
Radio Transmitter Daughter Board
Crowcon Detection Instruments Ltd
ANTENNA
P
O
S
2
M
O
D
1
0
V
3
ANT
4
IC1
HX1003
4
3 1
2
5
Q1
4
3 1
2
5
Q2
Vdigswitched
/Alarm-LED-1
To Display board.
1
2
3
4
J1
/Alarm-LED-2
C1
10nF
C2
1nF
R1
0R
C3
1nF
Filename: G2radio
PCB number: PC2128
Appendix B - Parts List (Sheet 1)
This appendix gives the parts list for the GasmanII Portable Gas Detector CPU/display PCB. For each circuit reference a
description of the component is given and, where appropriate, its case style is listed.
Circuit Ref. Component Description Case Style
C1 10uF 16V Tantalum Case A
C2 10uF 16V Tantalum Case A
C3 10nF 25V X7R Multi-layer Ceramic 0805
C4 1uF 16V Tantalum Case A
C5 100nF 16V X7R Multi-layer Ceramic 0805
C6 100nF 16V X7R Multi-layer Ceramic 0805
C7 15pF 25V COG Multi-layer Ceramic 0805
C8 15pF 25V COG Multi-layer Ceramic 0805
C9 1uF 16V Tantalum Case A
D1 GF1J SMA
D2 GF1J SMA
D3 1SS355 SOD123
IC1 Motorola H8/3834 100PQFP
IC2 Microchip 24C16 SO8
IC3 TC55 3V Regulator SOT89
IC4 MAX6316 SO8
Q1 IMT1 SOT23-6
R1 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R2 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R3 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R4 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R5 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R6 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R7 27k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R8 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R9 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R10 100k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R11 1M 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R13 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R14 1k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R15 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R16 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R17 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R18 100R 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R20 1k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
S1 Push Switch Omron B3S-1000 N/A
S1 Push Switch Omron B3S-1000 N/A
X1 2.51MHz Crystal N/A
X2 32.768kHz Crystal N/A
11
Appendix B - Parts List (Sheet 2) - Toxic
This appendix gives the parts list for the GasmanII Portable Gas Detector Main PCB - Toxic version. For each circuit
reference a description of the component is given and, where appropriate, its case style is listed.
Circuit Ref. Component Description Case Style
C1 10uF 16V Tantalum Case B
C2 100pF 25V COG Multi-layer Ceramic 0805
C3 10nF 25V X7R Multi-layer Ceramic 0805
C4 10nF 25V X7R Multi-layer Ceramic 0805
C5 1nF 25V X7R Multi-layer Ceramic 0805
C7 100pF 25V COG Multi-layer Ceramic 0805
C8 100pF 25V COG Multi-layer Ceramic 0805
C9 100pF 25V COG Multi-layer Ceramic 0805
C10 10uF 16V Tantalum Case B
C11 10nF 25V X7R Multi-layer Ceramic 0805
C12 1nF 25V X7R Multi-layer Ceramic 0805
C13 1nF 25V X7R Multi-layer Ceramic 0805
C14 1nF 25V X7R Multi-layer Ceramic 0805
C15 1nF 25V X7R Multi-layer Ceramic 0805
C16 100nF 16V X7R Multi-layer Ceramic 0805
C17 100pF 25V COG Multi-layer Ceramic 0805
C18 100nF 16V X7R Multi-layer Ceramic 0805
D1 1SS355 SOD123
D3 6V2 1.3W Zener Diode MELF
D4 6V2 1.3W Zener Diode MELF
F1 125mA N/A
FLT1 Supply Line Filter N/A
IC1 74HC240 SSOP20
IC2 LTC1152 SO8
IC3 MAX951 SO8
Q1 J177 SOT23-6
Q2 BC849 SOT23
R1 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R2 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R3 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R4 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R5 100k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R6 100k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R7 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R8 4k7 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R9 1k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R10 4k7 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R11 1M 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R12 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R14 1M 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R15 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R20 330R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R23 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R24 100k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R25 510k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R31 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R32 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
RV1 Varistor 1206
VR1 10k 0.1W Preset N/A
12
Appendix B - Parts List (Sheet 2) - Flammable
This appendix gives the parts list for the GasmanII Portable Gas Detector Main PCB - Flammable version. For each circuit
reference a description of the component is given and, where appropriate, its case style is listed.
Circuit Ref. Component Description Case Style
C1 1uF 16V Tantalum Case B
C2 10uF 16V Tantalum Case B
C3 1nF 25V X7R Multi-layer Ceramic 0805
C4 10nF 25V X7R Multi-layer Ceramic 0805
C5 2u2F 16V Tantalum Case B
C6 10nF 25V X7R Multi-layer Ceramic 0805
C7 1nF 25V X7R Multi-layer Ceramic 0805
C9 100nF 16V X7R Multi-layer Ceramic 0805
C10 100nF 16V X7R Multi-layer Ceramic 0805
C11 10nF 25V X7R Multi-layer Ceramic 0805
D1 1SS355 SOD123
D2 1SS355 SOD123
D3 6V2 1.3W Zener Diode MELF
D4 6V2 1.3W Zener Diode MELF
D5 6V2 1.3W Zener Diode MELF
D6 6V2 1.3W Zener Diode MELF
D7 ZHCS750 SOT23
D8 ZHCS750 SOT23
D9 GF1J SMA
F1 125mA N/A
IC1 74HC240 SSOP20
IC2 MAX4040 SOT23-5
IC3 MAX6327 SOT23
IC4 MAX8878 SOT23-5
IC5 MAX4040 SOT23-5
Q1 NDC632P SOT23-6
Q2 BSS123 SOT23
Q3 MMST2222A SOT23
Q4 BSS123 SOT23
R2 4k3 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R3 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R4 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R5 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R6 11k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R7 1M 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R9 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R10 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R11 0R 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R12 4k7 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R13 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R14 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R15 82k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R16 82k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R17 1M 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R19 4k7 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R20 330R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R21 1k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R22 1M 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R23 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R24 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R27 10R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
13
R31 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R32 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
VR1 10k 0.1W Preset N/A
VR2 Varistor 1206
9914
Appendix B - Parts List (Sheet 2) - Oxygen
This appendix gives the parts list for the GasmanII Portable Gas Detector Main PCB - Oxygen version. For each circuit
reference a description of the component is given and, where appropriate, its case style is listed.
Circuit Ref. Component Description Case Style
C1 10uF 16V Tantalum Case B
C2 10uF 16V Tantalum Case B
C3 10nF 25V X7R Multi-layer Ceramic 0805
C4 100nF 16V X7R Multi-layer Ceramic 0805
C5 10nF 25V X7R Multi-layer Ceramic 0805
C9 1nF 25V X7R Multi-layer Ceramic 0805
C10 10uF 16V Tantalum Case B
C19 1nF 25V X7R Multi-layer Ceramic 0805
D1 1SS355 SOD123
D3 6V2 1.3W Zener Diode MELF
D4 6V2 1.3W Zener Diode MELF
F1 125mA N/A
FLT1 Supply Line Filter N/A
IC1 74HC240 SSOP20
IC2 OP191 SO8
IC3 MAX951 SO8
Q1 IMT1 SOT23-6
Q2 BC849 SOT23
R1 270k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R2 1k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R3 2k7 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R4 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R5 2k7 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R6 2k7 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R7 3k9 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R8 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R9 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R10 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R11 100R 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R12 1M 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R18 2k7 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R20 330R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R23 10k 0.25W 2% 200ppm Nickel Barrier Resistor 1206
R31 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
R32 150R 0.4W 2% 200ppm Nickel Barrier Resistor 1210
TH1 NTC Thermistor Bead
VR1 10k 0.1W Preset N/A
VR2 Varistor 1206
15
Appendix B - Parts List (Sheet 3)
This appendix gives the parts list for the GasmanII Portable Gas Detector Sensor PCB. For each circuit reference a
description of the component is given and, where appropriate, its case style is listed.
Circuit Ref. Component Description Case Style
C1 1nF 25V X7R Multi-layer Ceramic 1206
D1 High Brightness LED T1.75
D2 High Brightness LED T1.75
LS1 AT-01 Buzzer N/A
R1 47R 0.5W 5% 200ppm Metal Film Resistor N/A
R2 47R 0.5W 5% 200ppm Metal Film Resistor N/A
16
Appendix B - Parts List (Sheet 4)
This appendix gives the parts list for the GasmanII Portable Gas Detector Low-Power Transmitter PCB. For each circuit
reference a description of the component is given and, where appropriate, its case style is listed.
Circuit Ref. Component Description Case Style
C1 10nF 25V X7R Multi-layer Ceramic 1206
C2 1nF 25V X7R Multi-layer Ceramic 0805
C3 1nF 25V X7R Multi-layer Ceramic 0805
IC1 HX1003 Transmitter Module SM-04
Q1 BSS284 MOSFET SOT23-6
Q2 BSS284 MOSFET SOT23-6
17
/
