From eb56b94578f1453147ab3b6af7e7e38c33aa0bb4 Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Sat, 16 Jan 2016 16:22:13 -0800 Subject: [PATCH] Use 27k resistors on the input to create a false ground This replaces the odd network of 33k resistors; testing shows that this works 'just fine thanks'. Signed-off-by: Keith Packard --- chaoskey.pcb | 33 +++------ chaoskey.sch | 192 ++++++++++++++++++++++++--------------------------- 2 files changed, 101 insertions(+), 124 deletions(-) diff --git a/chaoskey.pcb b/chaoskey.pcb index 0231940..58b5bed 100644 --- a/chaoskey.pcb +++ b/chaoskey.pcb @@ -963,13 +963,6 @@ Element["" "0402" "C4" "1uF" 648.00mil 777.00mil -22.00mil 22.00mil 1 80 ""] ) -Element["" "0402" "R7" "33k" 604.26mil 935.00mil 0.6416mm 70.00mil 2 80 ""] -( - Pad[-15.74mil -3.93mil -15.74mil 3.93mil 19.68mil 20.00mil 25.68mil "1" "1" "square"] - Pad[15.74mil -3.93mil 15.74mil 3.93mil 19.68mil 20.00mil 25.68mil "2" "2" "square"] - - ) - Element["" "0402" "R2" "4.7K" 12.7950mm 904.00mil -0.6030mm -23.00mil 0 80 ""] ( Pad[-15.74mil -3.93mil -15.74mil 3.93mil 19.68mil 20.00mil 25.68mil "1" "1" "square"] @@ -1005,7 +998,7 @@ Element["" "0402" "C5" "1uF" 554.00mil 23.3360mm 24.00mil -0.5014mm 3 80 ""] ) -Element["" "0402" "R5" "33k" 17.7480mm 823.00mil -0.5522mm -17.00mil 0 80 ""] +Element["" "0402" "R5" "27k" 17.7480mm 823.00mil -0.5522mm -17.00mil 0 80 ""] ( Pad[-15.74mil -3.93mil -15.74mil 3.93mil 19.68mil 20.00mil 25.68mil "1" "1" "square"] Pad[15.74mil -3.93mil 15.74mil 3.93mil 19.68mil 20.00mil 25.68mil "2" "2" "square"] @@ -1156,28 +1149,28 @@ Element["" "0402" "C6" "0.1uF" 677.00mil 777.00mil -84.00mil 31.50mil 1 100 ""] ) -Element["" "0402" "C2" "1uF" 648.00mil 832.74mil 84.00mil -31.50mil 3 100 ""] +Element["" "0402" "C2" "4.7uF" 648.00mil 832.74mil 84.00mil -31.50mil 3 100 ""] ( Pad[-3.93mil -15.74mil 3.93mil -15.74mil 19.68mil 20.00mil 25.68mil "1" "1" "square"] Pad[-3.93mil 15.74mil 3.93mil 15.74mil 19.68mil 20.00mil 25.68mil "2" "2" "square"] ) -Element["" "0402" "R9" "470" 648.00mil 885.26mil 84.00mil -31.50mil 3 100 ""] +Element["" "0402" "R9" "4.7k" 648.00mil 885.26mil 84.00mil -31.50mil 3 100 ""] ( Pad[-3.93mil -15.74mil 3.93mil -15.74mil 19.68mil 20.00mil 25.68mil "1" "1" "square"] Pad[-3.93mil 15.74mil 3.93mil 15.74mil 19.68mil 20.00mil 25.68mil "2" "2" "square"] ) -Element["" "0402" "R8" "47k" 687.00mil 894.26mil -84.00mil 31.50mil 1 100 ""] +Element["" "0402" "R8" "470k" 687.00mil 894.26mil -84.00mil 31.50mil 1 100 ""] ( Pad[-3.93mil 15.74mil 3.93mil 15.74mil 19.68mil 20.00mil 25.68mil "1" "1" "square"] Pad[-3.93mil -15.74mil 3.93mil -15.74mil 19.68mil 20.00mil 25.68mil "2" "2" "square"] ) -Element["" "0402" "R6" "33k" 715.00mil 773.00mil -84.00mil 31.50mil 1 100 ""] +Element["" "0402" "R6" "27k" 715.00mil 773.00mil -84.00mil 31.50mil 1 100 ""] ( Pad[-3.93mil 15.74mil 3.93mil 15.74mil 19.68mil 20.00mil 25.68mil "1" "1" "square"] Pad[-3.93mil -15.74mil 3.93mil -15.74mil 19.68mil 20.00mil 25.68mil "2" "2" "square"] @@ -1313,8 +1306,6 @@ Layer(1 "top") Line[554.00mil 903.00mil 554.00mil 885.00mil 10.00mil 20.00mil "clearline"] Line[554.00mil 885.00mil 529.00mil 860.00mil 10.00mil 20.00mil "clearline"] Line[529.00mil 860.00mil 506.00mil 860.00mil 10.00mil 20.00mil "clearline"] - Line[588.52mil 935.00mil 588.52mil 23.3050mm 10.00mil 20.00mil "clearline"] - Line[588.52mil 23.3050mm 574.00mil 903.00mil 10.00mil 20.00mil "clearline"] Line[574.00mil 903.00mil 554.00mil 903.00mil 10.00mil 20.00mil "clearline"] Line[554.00mil 903.00mil 554.00mil 903.00mil 10.00mil 20.00mil "clearline"] Line[715.00mil 20.0340mm 715.00mil 20.8910mm 10.00mil 20.00mil "clearline"] @@ -1327,7 +1318,6 @@ Layer(1 "top") Line[520.00mil 768.00mil 506.00mil 782.00mil 10.00mil 20.00mil "clearline"] Line[714.48mil 823.00mil 714.48mil 923.52mil 10.00mil 20.00mil "clearline"] Line[714.48mil 923.52mil 703.00mil 935.00mil 10.00mil 20.00mil "clearline"] - Line[703.00mil 935.00mil 620.00mil 935.00mil 10.00mil 20.00mil "clearline"] Line[687.00mil 910.00mil 657.00mil 910.00mil 10.00mil 20.00mil "clearline"] Line[657.00mil 910.00mil 648.00mil 901.00mil 10.00mil 20.00mil "clearline"] Line[648.00mil 901.00mil 629.00mil 901.00mil 10.00mil 20.00mil "clearline"] @@ -1374,6 +1364,8 @@ Layer(1 "top") Line[648.00mil 817.00mil 648.00mil 796.48mil 25.00mil 20.00mil "clearline"] Line[648.00mil 796.48mil 677.00mil 796.48mil 25.00mil 20.00mil "clearline"] Line[677.00mil 796.48mil 677.00mil 817.00mil 25.00mil 20.00mil "clearline"] + Line[703.00mil 935.00mil 606.00mil 935.00mil 10.00mil 20.00mil "clearline"] + Line[606.00mil 935.00mil 574.00mil 903.00mil 10.00mil 20.00mil "clearline"] ) Layer(2 "bottom") ( @@ -1620,7 +1612,8 @@ NetList() Net("unnamed_net11" "(unknown)") ( Connect("C5-2") - Connect("R7-1") + Connect("R5-2") + Connect("R6-1") Connect("U4-3") ) Net("unnamed_net12" "(unknown)") @@ -1705,18 +1698,12 @@ NetList() Connect("U2-2") ) Net("unnamed_net31" "(unknown)") - ( - Connect("R5-2") - Connect("R6-1") - Connect("R7-2") - ) - Net("unnamed_net32" "(unknown)") ( Connect("R8-1") Connect("R9-2") Connect("U4-4") ) - Net("unnamed_net33" "(unknown)") + Net("unnamed_net32" "(unknown)") ( Connect("C2-2") Connect("R9-1") diff --git a/chaoskey.sch b/chaoskey.sch index 4e77f95..2304a97 100644 --- a/chaoskey.sch +++ b/chaoskey.sch @@ -475,55 +475,55 @@ N 73200 67500 75000 67500 4 N 73500 67500 73500 67200 4 N 74700 67500 74700 67200 4 C 74600 65900 1 0 0 gnd.sym -N 75900 67500 76800 67500 4 -C 75100 69500 1 270 0 capacitor.sym +N 75900 67500 77800 67500 4 +C 77500 69500 1 270 0 capacitor.sym { -T 75800 69300 5 10 0 0 270 0 1 +T 78200 69300 5 10 0 0 270 0 1 device=CAPACITOR -T 75400 69200 5 10 1 1 0 0 1 +T 77800 69200 5 10 1 1 0 0 1 refdes=C4 -T 76000 69300 5 10 0 0 270 0 1 +T 78400 69300 5 10 0 0 270 0 1 symversion=0.1 -T 75400 68800 5 10 1 1 0 0 1 +T 77800 68800 5 10 1 1 0 0 1 value=1uF -T 75100 69500 5 10 0 1 0 0 1 +T 77500 69500 5 10 0 1 0 0 1 footprint=0402 -T 75100 69500 5 10 0 1 0 0 1 +T 77500 69500 5 10 0 1 0 0 1 loadstatus=smt -T 75100 69500 5 10 0 1 0 0 1 +T 77500 69500 5 10 0 1 0 0 1 vendor=digikey -T 75100 69500 5 10 0 1 0 0 1 +T 77500 69500 5 10 0 1 0 0 1 vendor_part_number=490-10017-1-ND } -N 75300 69900 75300 69500 4 -N 75300 69700 77300 69700 4 -N 76500 69700 76500 69500 4 -N 77300 69700 77300 67700 4 -C 75100 70800 1 0 0 3.3V-plus.sym -C 76400 64100 1 0 0 gnd.sym -C 75200 68300 1 0 0 gnd.sym -N 77800 67300 79200 67300 4 +N 77700 69900 77700 69500 4 +N 77700 69700 78300 69700 4 +N 76500 69700 76500 68400 4 +N 78300 69700 78300 67700 4 +C 77500 70800 1 0 0 3.3V-plus.sym +C 77400 64100 1 0 0 gnd.sym +C 77600 68300 1 0 0 gnd.sym +N 78800 67300 80200 67300 4 { -T 78200 67400 5 10 1 1 0 0 1 +T 79200 67400 5 10 1 1 0 0 1 netname=randombits } -C 75200 70800 1 270 0 inductor.sym +C 77600 70800 1 270 0 inductor.sym { -T 75700 70600 5 10 0 0 270 0 1 +T 78100 70600 5 10 0 0 270 0 1 device=INDUCTOR -T 75500 70500 5 10 1 1 0 0 1 +T 77900 70500 5 10 1 1 0 0 1 refdes=L3 -T 75900 70600 5 10 0 0 270 0 1 +T 78300 70600 5 10 0 0 270 0 1 symversion=0.1 -T 75500 70100 5 10 1 1 0 0 1 +T 77900 70100 5 10 1 1 0 0 1 value=bead -T 75200 70800 5 10 0 1 270 0 1 +T 77600 70800 5 10 0 1 270 0 1 footprint=0402 -T 75200 70800 5 10 0 1 270 0 1 +T 77600 70800 5 10 0 1 270 0 1 vendor=digikey -T 75200 70800 5 10 0 1 270 0 1 +T 77600 70800 5 10 0 1 270 0 1 vendor_part_number=240-2554-1-ND -T 75200 70800 5 10 0 1 270 0 1 +T 77600 70800 5 10 0 1 270 0 1 loadstatus=smt } C 73300 65800 1 0 0 nc-bottom.sym @@ -903,123 +903,113 @@ T 67500 66400 5 10 0 1 0 0 1 vendor_part_number=P27.0KLCT-ND } N 67600 66400 67600 66500 4 -C 76600 68600 1 90 0 resistor.sym +C 76600 67500 1 90 0 resistor.sym { -T 76200 68900 5 10 0 0 90 0 1 +T 76200 67800 5 10 0 0 90 0 1 device=RESISTOR -T 76700 69200 5 10 1 1 0 0 1 +T 76700 68100 5 10 1 1 0 0 1 refdes=R6 -T 76600 68600 5 10 0 0 0 0 1 +T 76600 67500 5 10 0 0 0 0 1 footprint=0402 -T 76700 68800 5 10 1 1 0 0 1 -value=33k +T 76700 67700 5 10 1 1 0 0 1 +value=27k } -C 76800 66100 1 0 0 resistor.sym +C 77800 66100 1 0 0 resistor.sym { -T 77100 66500 5 10 0 0 0 0 1 +T 78100 66500 5 10 0 0 0 0 1 device=RESISTOR -T 77100 66400 5 10 1 1 0 0 1 +T 78100 66400 5 10 1 1 0 0 1 refdes=R8 -T 76800 66100 5 10 0 0 0 0 1 +T 77800 66100 5 10 0 0 0 0 1 footprint=0402 -T 77100 65900 5 10 1 1 0 0 1 -value=47k +T 78100 65900 5 10 1 1 0 0 1 +value=470k } -C 75600 68500 1 0 0 resistor.sym +C 76600 66600 1 90 0 resistor.sym { -T 75900 68900 5 10 0 0 0 0 1 +T 76200 66900 5 10 0 0 90 0 1 device=RESISTOR -T 75900 68800 5 10 1 1 0 0 1 +T 76700 67200 5 10 1 1 0 0 1 refdes=R5 -T 75600 68500 5 10 0 0 0 0 1 +T 76600 66600 5 10 0 0 90 0 1 footprint=0402 -T 75900 68300 5 10 1 1 0 0 1 -value=33k +T 76700 66900 5 10 1 1 0 0 1 +value=27k } -C 76600 65300 1 90 0 resistor.sym +C 77600 65300 1 90 0 resistor.sym { -T 76200 65600 5 10 0 0 90 0 1 +T 77200 65600 5 10 0 0 90 0 1 device=RESISTOR -T 76000 65900 5 10 1 1 0 0 1 +T 77000 65900 5 10 1 1 0 0 1 refdes=R9 -T 76600 65300 5 10 0 0 0 0 1 +T 77600 65300 5 10 0 0 0 0 1 footprint=0402 -T 76000 65500 5 10 1 1 0 0 1 -value=470 +T 77000 65500 5 10 1 1 0 0 1 +value=4.7k } -C 76600 67700 1 90 0 resistor.sym +N 77100 68600 77700 68600 4 +C 77700 64400 1 90 0 capacitor.sym { -T 76200 68000 5 10 0 0 90 0 1 -device=RESISTOR -T 76700 68300 5 10 1 1 0 0 1 -refdes=R7 -T 76600 67700 5 10 0 0 0 0 1 -footprint=0402 -T 76700 67900 5 10 1 1 0 0 1 -value=33k -} -N 74700 68600 75600 68600 4 -C 76700 64400 1 90 0 capacitor.sym -{ -T 76000 64600 5 10 0 0 90 0 1 +T 77000 64600 5 10 0 0 90 0 1 device=CAPACITOR -T 76000 65000 5 10 1 1 0 0 1 +T 77000 65000 5 10 1 1 0 0 1 refdes=C2 -T 75800 64600 5 10 0 0 90 0 1 +T 76800 64600 5 10 0 0 90 0 1 symversion=0.1 -T 76700 64400 5 10 0 0 0 0 1 +T 77700 64400 5 10 0 0 0 0 1 footprint=0402 -T 76000 64600 5 10 1 1 0 0 1 -value=1uF +T 77000 64600 5 10 1 1 0 0 1 +value=4.7uF } -N 76500 67700 76500 67500 4 -N 76800 67100 76500 67100 4 -N 76500 67100 76500 66200 4 -N 76500 66200 76800 66200 4 -N 78100 67300 78100 66200 4 -N 78100 66200 77700 66200 4 -C 77200 66600 1 0 0 gnd.sym -C 74900 68600 1 90 0 capacitor.sym +N 77800 67100 77500 67100 4 +N 77500 67100 77500 66200 4 +N 77500 66200 77800 66200 4 +N 79100 67300 79100 66200 4 +N 79100 66200 78700 66200 4 +C 78200 66600 1 0 0 gnd.sym +C 77300 68600 1 90 0 capacitor.sym { -T 74200 68800 5 10 0 0 90 0 1 +T 76600 68800 5 10 0 0 90 0 1 device=CAPACITOR -T 74300 69200 5 10 1 1 0 0 1 +T 76700 69200 5 10 1 1 0 0 1 refdes=C6 -T 74000 68800 5 10 0 0 90 0 1 +T 76400 68800 5 10 0 0 90 0 1 symversion=0.1 -T 74200 68700 5 10 1 1 0 0 1 +T 76600 68700 5 10 1 1 0 0 1 value=0.1uF -T 74900 68600 5 10 0 1 90 0 1 +T 77300 68600 5 10 0 1 90 0 1 footprint=0402 -T 74900 68600 5 10 0 1 90 0 1 +T 77300 68600 5 10 0 1 90 0 1 loadstatus=smt -T 74900 68600 5 10 0 1 90 0 1 +T 77300 68600 5 10 0 1 90 0 1 vendor=digikey -T 74900 68600 5 10 0 1 90 0 1 +T 77300 68600 5 10 0 1 90 0 1 vendor_part_number=399-3027-1-ND } -N 75300 69700 74700 69700 4 -N 74700 69700 74700 69500 4 -T 76400 70100 9 10 1 0 0 0 1 -To minimize input-bias-current errors, R8 = R7 + 1/2 R6 -T 77300 65000 9 10 1 0 0 0 1 +N 76500 69700 77700 69700 4 +N 77100 69700 77100 69500 4 +T 78300 65000 9 10 1 0 0 0 1 * star ground -T 77400 66700 9 10 1 0 0 0 1 +T 78400 66700 9 10 1 0 0 0 1 * -T 76600 64300 9 10 1 0 0 0 1 +T 77600 64300 9 10 1 0 0 0 1 * -T 75400 68400 9 10 1 0 0 0 1 +T 77800 68400 9 10 1 0 0 0 1 * -C 76800 66900 1 0 0 opamp.sym +C 77800 66900 1 0 0 opamp.sym { -T 77900 68200 5 10 0 0 0 0 1 +T 78900 68200 5 10 0 0 0 0 1 device=IC -T 77400 68000 5 10 1 1 0 0 1 +T 78400 68000 5 10 1 1 0 0 1 refdes=U4 -T 77900 68800 5 10 0 0 0 0 1 +T 78900 68800 5 10 0 0 0 0 1 symversion=0.1 -T 77400 67700 5 10 1 1 0 0 1 +T 78400 67700 5 10 1 1 0 0 1 value=OPA356 -T 76800 66900 5 10 0 0 0 0 1 +T 77800 66900 5 10 0 0 0 0 1 footprint=SOT23-5 } +C 76400 66300 1 0 0 gnd.sym +T 76600 66200 9 10 1 0 0 0 2 +* + -- 2.30.2