Document AC/DC coupling differences

2017-04-04 16:18:50 -04:00 · 2017-04-04 16:18:50 -04:00 · b51ad9a9c6
parent 1ce6f742dd
commit b51ad9a9c6
2 changed files with 249 additions and 235 deletions
--- a/channel0.sch
+++ b/channel0.sch
@ -114,7 +114,7 @@ F 3 "" H 2200 1800 50  0001 C CNN
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 Text Notes 1950 1000 0    60   ~ 0
-AC Coupling\n3dB down @ 0.04Hz
+Optional AC Coupling\n3dB down @ 0.04Hz
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@ -304,8 +304,8 @@ Wire Wire Line
 Connection ~ 1750 1500
 Wire Wire Line
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-When DC coupled, sensor failure grounds output.
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+For AC coupling: Populate as shown. Trim pot not required\n\nFor DC coupling: Replace C206,C208 with 5 kOhm resistors.\nR202,R208 may be omitted. Trim pot required. \nCut jumpers on pot footprint before installation.
 Text Notes 2750 2350 0    39   ~ 0
 CMRR: >95dB\nVoltage Noise Density @ G=15: <23.5nV/√Hz\nVoltage Noise (0.1-10Hz): < 0.8μV p-p\nSupply Current: <425μA
 Text Notes 7080 2570 0    39   ~ 0
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 Problems:\n\n  - USB-1208FS has fixed single-ended range of  ±10V\n    - Drop in upgrade to USB-1608FS (16bit and variable range)\n    - Mitigated initially by running on 18V via two 9V batteries.\n\n  - R202, R208, R212, R218; 39M only available in thick film. \n    - More (slightly) 1/f noise and ±5% accuracy.\n\n  - AC coupling isn't optional in this design. Rhodri keen\n     to try AC route first; add cost / complexity later if needed.
 Text HLabel 9000 1700 2    60   Output ~ 0
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@ -474,363 +474,363 @@ Wire Wire Line
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-F 3 "" H 8050 4000 50  0001 C CNN
-	1    8050 4000
+P 8090 4180
+F 0 "#PWR034" H 8090 3930 50  0001 C CNN
+F 1 "GNDA" H 8090 4030 50  0000 C CNN
+F 2 "" H 8090 4180 50  0001 C CNN
+F 3 "" H 8090 4180 50  0001 C CNN
+	1    8090 4180
 	0    -1   -1   0   
 $EndComp
 $Comp
 L GNDA #PWR035
 U 1 1 58D92467
-P 6250 3700
-F 0 "#PWR035" H 6250 3450 50  0001 C CNN
-F 1 "GNDA" H 6250 3550 50  0000 C CNN
-F 2 "" H 6250 3700 50  0001 C CNN
-F 3 "" H 6250 3700 50  0001 C CNN
-	1    6250 3700
+P 6290 3880
+F 0 "#PWR035" H 6290 3630 50  0001 C CNN
+F 1 "GNDA" H 6290 3730 50  0000 C CNN
+F 2 "" H 6290 3880 50  0001 C CNN
+F 3 "" H 6290 3880 50  0001 C CNN
+	1    6290 3880
 	1    0    0    -1  
 $EndComp
 $Comp
@ -924,8 +924,8 @@ Connection ~ 9650 850
 Wire Wire Line
 	1400 1250 1400 1650
 Wire Wire Line
-	1400 3050 1400 3450
-Connection ~ 1400 3200
+	1440 3230 1440 3630
+Connection ~ 1440 3380
 Wire Wire Line
 	2050 1400 1400 1400
 Connection ~ 1400 1400
@ -989,9 +989,9 @@ Wire Wire Line
 	9420 1450 10150 1450
 Connection ~ 9900 1450
 Connection ~ 9650 1450
-Connection ~ 7600 4000
+Connection ~ 7640 4180
 Wire Wire Line
-	7600 3900 7600 4000
+	7640 4080 7640 4180
 Connection ~ 7600 2200
 Wire Wire Line
 	7600 2110 7600 2200
@ -1026,39 +1026,53 @@ Wire Wire Line
 $Comp
 L V- #PWR039
 U 1 1 58E47292
-P 1580 4130
-F 0 "#PWR039" H 1580 3980 50  0001 C CNN
-F 1 "V-" H 1580 4270 50  0000 C CNN
-F 2 "" H 1580 4130 50  0000 C CNN
-F 3 "" H 1580 4130 50  0000 C CNN
-	1    1580 4130
+P 1620 4310
+F 0 "#PWR039" H 1620 4160 50  0001 C CNN
+F 1 "V-" H 1620 4450 50  0000 C CNN
+F 2 "" H 1620 4310 50  0000 C CNN
+F 3 "" H 1620 4310 50  0000 C CNN
+	1    1620 4310
 	-1   0    0    1   
 $EndComp
 $Comp
 L POT_TRIM RV202
 U 1 1 58E47298
-P 1580 3890
-F 0 "RV202" V 1500 3890 50  0000 C CNN
-F 1 "100k" V 1580 3890 50  0000 C CNN
-F 2 "footprints:Potentiometer_Trimmer_Bourns_3296W_w_Bypass" H 1580 3890 50  0001 C CNN
-F 3 "" H 1580 3890 50  0001 C CNN
-	1    1580 3890
+P 1620 4070
+F 0 "RV202" V 1540 4070 50  0000 C CNN
+F 1 "100k" V 1620 4070 50  0000 C CNN
+F 2 "footprints:Potentiometer_Trimmer_Bourns_3296W_w_Bypass" H 1620 4070 50  0001 C CNN
+F 3 "" H 1620 4070 50  0001 C CNN
+	1    1620 4070
 	0    1    1    0   
 $EndComp
 Wire Wire Line
-	1400 3750 1400 3890
+	1440 3930 1440 4070
 Wire Wire Line
-	1580 4130 1580 4040
+	1620 4310 1620 4220
 Wire Wire Line
-	1400 3890 1430 3890
+	1440 4070 1470 4070
 Wire Wire Line
-	1750 3890 1750 3750
+	1790 4070 1790 3930
 Wire Wire Line
-	1730 3890 1750 3890
+	1770 4070 1790 4070
 Wire Wire Line
 	1400 2090 1400 1950
 Wire Wire Line
 	1750 2090 1750 1950
 Text Notes 450  7910 0    60   ~ 0
   Copyright 2017 University of Western Ontario\n\n   Licensed under the Apache License, Version 2.0 (the "License");\n   you may not use this file except in compliance with the License.\n   You may obtain a copy of the License at\n\n       http://www.apache.org/licenses/LICENSE-2.0\n\n   Unless required by applicable law or agreed to in writing, software\n   distributed under the License is distributed on an "AS IS" BASIS,\n   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n   See the License for the specific language governing permissions and\n   limitations under the License.
+Wire Notes Line
+	1330 1970 1810 1970
+Wire Notes Line
+	1810 1970 1810 2190
+Wire Notes Line
+	1810 2190 1330 2190
+Wire Notes Line
+	1330 2190 1330 1970
+Wire Notes Line
+	1810 2100 1920 2100
+Wire Notes Line
+	1920 2100 1920 2010
+Wire Notes Line
+	1920 2010 2050 2010
 $EndSCHEMATC
--- a/pdf/schematic.pdf
+++ b/pdf/schematic.pdf