[FIX] Schematics: Revised values and PCB errata text

* fixed trim pot range at VU meter
* TODOs removed (5V V_LED didn't work out, 10uF at LM386 wasn't better, VU meter filtering not needed)
* phantom power voltage changed and readme chapter added
* hardware errata: gain pot. pins are swapped, ground plane isn't fully connected

Footprints and PCB aren't fixed to keep the schematic compatible with the existing PCBs!

README.md

@@ -80,8 +80,6 @@ For the microphone preamp, we are using the NE5534 low-noise opamp with a circui
 In a normal mixer, you would be able to lower the microphone's volume to zero.
 But in our case we just need on/ off and some gain range to adjust for different microphones and loudness of different people.
 
-TODO: Integrate the On-Air button with it's LEDs
-
 
 ### Line Input/ Input Module
 The line input must not be amplified at all, because loudness control of the headphones is done by the headphone amplifier section.
@@ -121,6 +119,11 @@ When searching for VU meter circuits, many use the LM3916 LED bar graph driver,
 But this chip is obsolete and not produced any more, so we designed our own chain of comparators to drive a set of LEDs.
 
 
+### Phantom Power
+The cheap but still decent Superlux HMC-660 headset is known to sound quite bad with standard 48 V phantom power (which can be easily fixed by adding some resistors inside the XLR connector).
+But when I bought one in April 2021, it worked just fine with 48 V and didn't really work with 12 or 15 V.
+So, if phantom power should be a feature of the interpreter unit, it probably best to have standard 48 V instead of any special treatment for one special headset.
+
 
 ## User Interface
 The user interface should enable the interpreters to adjust their microphone gain and headphone mix on their own.
@@ -269,24 +272,23 @@ Electrolytic capacitors should have 25 V voltage rating, unless otherwise specif
 | Count | Manufacturer + Art. No.   | Description                       | €/ pc.| Distributor Order No.
 |-------|---------------------------|-----------------------------------|-------|----------------------
 | 1     | Neutrik NCJ6FA-H          | Stage Line Input                  | 1.10  | Thomann 250931
-| 1     | Neutrik NC3MAAH           | Mix Line Output                   | 0.78  | Voelkner X39973
+| 1     | Neutrik NC3MAAH           | Mix Line Output                   | 0.78  | Voelkner X39973, Mouser 568-NC3MAAH
 | 1     | PTSM 0,5/ 2-2,5-V THR     | PCB Output                        | 0.50  | Mouser 651-1770953, DigiKey 277-2086-1-ND
 | 1     | PTSM 0,5/ 3-2,5-H THR     | PCB PowerSupply                   | 0.70  | Mouser 651-1770898, DigiKey 277-2080-1-ND
 | 1     | PTSM 0,5/ 4-2,5-V THR     | PCB Inputs                        | 0.80  | Mouser 651-1770979, DigiKey 277-2088-1-ND
 | 1     | Vishay M64Y104            | 100K trim pot: Line input adj.    | 0.83  | Reichelt VIS M64Y104KB40
-| 2     | LM833N                    | Generic Op-Amp                    | 0.75  | Mouser 926-LM833N/NOPB, DigiKey 296-44419-5-ND
+| 2     | LM833N                    | Generic Op-Amp                    | 0.75  | DigiKey 296-44419-5-ND, Mouser 926-LM833N/NOPB
 | 1     | DRV134PA                  | Line Driver                       | 4.75  | Mouser 595-DRV134PA, DigiKey DRV134PA-ND
 | 3     | DIP-8 Socket              | for LM833N, DRV134PA              | 0.03  | Reichelt GS 8
 | 1     | Cer. Cap. 22pF            | C_Disc_D5.0mm_W2.5mm_P5.00mm      | 0.33  | DigiKey 399-9723-ND, Mouser TODO
 | 1     | Cer. Cap. 47pF            | C_Disc_D5.0mm_W2.5mm_P5.00mm      | 0.33  | DigiKey 399-C315C470K5G5TA-ND, Mouser TODO
 | 1     | Cer. Cap. 220pF           | C_Disc_D5.0mm_W2.5mm_P5.00mm      | 0.31  | DigiKey 399-9802-ND, Mouser TODO
-| 4     | Cer. Cap. 100nF           | C_Disc_D5.0mm_W2.5mm_P5.00mm      | 0.20  | DigiKey 399-4329-ND, Mouser TODO
+| 6     | Cer. Cap. 100nF           | C_Disc_D5.0mm_W2.5mm_P5.00mm      | 0.20  | DigiKey 399-4329-ND, Mouser TODO
-| 2     | Cer. Cap. 1uF             | C_Disc_D5.0mm_W2.5mm_P5.00mm      |       | (TODO: just use 100 nF or an el. cap.)
 | 6     | 10K                       | Metal film resistor               | 0.02  | Average price at 100 pcs
 | 5     | 22K                       | Metal film resistor               | 0.02  | Average price at 100 pcs
 | 1     | 3.3K                      | Metal film resistor               | 0.02  | Average price at 100 pcs
 | 1     | 47K                       | Metal film resistor               | 0.02  | Average price at 100 pcs
-|       |                           | **SUM**                           | 13.48 | (1uF calculated as 100nF)
+|       |                           | **SUM**                           | 13.48 |
 
 
 #### Channel Strip Components
@@ -336,7 +338,7 @@ Electrolytic capacitors should have 25 V voltage rating, unless otherwise specif
 | 1     | 56R                       | Metal film resistor               | 0.02  | Average price at 100 pcs
 | 1     | 27K 1%                    | Metal film resistor               | 0.02  | Average price at 100 pcs
 | 1     | 330R                      | Metal film resistor               | 0.02  | Average price at 100 pcs
-| 2     | 680R 1%                   | Metal film resistor               | 0.02  | Average price at 100 pcs
+| 2     | 6.8K 1%                   | Metal film resistor               | 0.02  | Average price at 100 pcs
 | 1     | 820R                      | Metal film resistor               | 0.02  | Average price at 100 pcs
 | 1     | 330K                      | Metal film resistor               | 0.02  | Average price at 100 pcs
 | 2     | 1K 1%                     | Metal film resistor               | 0.02  | Average price at 100 pcs

schematics/c3lingo_unit-assembly/c3lingo_unit-assembly.pro

@@ -1,4 +1,4 @@
-update=Saturday, 29 May 2021 at 00:01:50
+update=Thursday, 02 September 2021 at 20:45:35
 last_client=kicad
 [general]
 version=1

schematics/c3lingo_unit-assembly/c3lingo_unit-assembly.sch

@@ -5,10 +5,10 @@ $Descr A4 11693 8268
 encoding utf-8
 Sheet 1 5
 Title "c3lingo interpeter unit"
-Date "2021-05-28"
+Date "2021-09-02"
-Rev "v0.2"
+Rev "v0.2.1"
 Comp "Jannik Beyerstedt (jtbx)"
-Comment1 "Prototype 1"
+Comment1 "Prototype 1 (with errata)"
 Comment2 ""
 Comment3 ""
 Comment4 ""

schematics/c3lingo_unit-assembly/c3lingo_unit-channel/c3lingo_unit-channel.sch

@@ -5,10 +5,10 @@ $Descr A3 16535 11693
 encoding utf-8
 Sheet 3 5
 Title "c3lingo interpeter unit -- channel strip"
-Date "2021-05-28"
+Date "2021-09-02"
-Rev "v0.2"
+Rev "v0.2.1"
 Comp "Jannik Beyerstedt (jtbx)"
-Comment1 "Prototype 1"
+Comment1 "Prototype 1 (with errata)"
 Comment2 ""
 Comment3 ""
 Comment4 ""
@@ -100,8 +100,8 @@ F 4 "+DIP-14 Socket" H 7100 8400 50  0001 C CNN "Model"
 	5    7100 8400
 	0    -1   -1   0   
 $EndComp
-Text Notes 1850 7900 0    50   ~ 0
+Text Notes 1850 8000 0    50   ~ 0
-Buffer/ Rectifier\nGain: 3.9
+Buffer/ Rectifier\nGain: 15\n(3.9 + 12 dB for\ntrim pot. headroom)
 $Comp
 L Comparator:LM339 U306
 U 5 1 60B42907
@@ -195,7 +195,7 @@ AR Path="/60AE7597/60B42949" Ref="R420"  Part="1"
 AR Path="/60AE80F3/60B42949" Ref="R520"  Part="1" 
 AR Path="/60B42949" Ref="R120"  Part="1" 
 F 0 "R320" V 2843 6500 50  0000 C CNN
-F 1 "3.9K" V 2934 6500 50  0000 C CNN
+F 1 "15K" V 2934 6500 50  0000 C CNN
 F 2 "Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 2980 6500 50  0001 C CNN
 F 3 "~" H 3050 6500 50  0001 C CNN
 	1    3050 6500
@@ -732,7 +732,7 @@ Wire Wire Line
 Wire Wire Line
 	9900 10800 9900 10500
 Text Notes 4250 8450 0    50   ~ 0
-Signal Smoothing\nTODO: Remove all together!?
+Signal Smoothing\n==> DNP (not required)
 $Comp
 L Device:R R347
 U 1 1 60B4292A
@@ -1345,8 +1345,6 @@ F 3 "" H 5550 7800 50  0001 C CNN
 	1    5550 7800
 	1    0    0    -1  
 $EndComp
-Text Notes 13550 6700 0    50   ~ 0
-TODO: Try with V_LED = 5V\nrd: 2.3 V (390R @15V)\ngn: 2.4 V (390R @15V)\nye: 2.6 V (390R @15V)
 $Comp
 L power:+15V #PWR0329
 U 1 1 60B429E4
@@ -2160,7 +2158,7 @@ F 4 "low ESR electrolytic // plastic film" H 1750 3500 50  0001 C CNN "Model"
 	0    -1   -1   0   
 $EndComp
 Text Notes 1300 4000 0    50   ~ 10
-Phantom Power\n(15V)
+Phantom Power\n(48V)
 Wire Wire Line
 	1300 3500 1500 3500
 Wire Wire Line
@@ -2240,7 +2238,7 @@ AR Path="/60AE7597/5FDA0F68" Ref="R411"  Part="1"
 AR Path="/60AE80F3/5FDA0F68" Ref="R511"  Part="1" 
 AR Path="/5FDA0F68" Ref="R111"  Part="1" 
 F 0 "R311" H 1570 3296 50  0000 L CNN
-F 1 "680R 1%" H 1570 3205 50  0000 L CNN
+F 1 "6.8K 1%" H 1570 3205 50  0000 L CNN
 F 2 "Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 1430 3250 50  0001 C CNN
 F 3 "~" H 1500 3250 50  0001 C CNN
 	1    1500 3250
@@ -2255,7 +2253,7 @@ AR Path="/60AE7597/5FD87CA8" Ref="R407"  Part="1"
 AR Path="/60AE80F3/5FD87CA8" Ref="R507"  Part="1" 
 AR Path="/5FD87CA8" Ref="R107"  Part="1" 
 F 0 "R307" H 1430 2704 50  0000 R CNN
-F 1 "680R 1%" H 1430 2795 50  0000 R CNN
+F 1 "6.8K 1%" H 1430 2795 50  0000 R CNN
 F 2 "Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal" V 1430 2750 50  0001 C CNN
 F 3 "~" H 1500 2750 50  0001 C CNN
 	1    1500 2750
@@ -2649,8 +2647,6 @@ F 3 "~" H 12850 4050 50  0001 C CNN
 	1    12850 4050
 	-1   0    0    -1  
 $EndComp
-Text Notes 14400 2500 0    50   ~ 0
-TODO: Change to 10 uF?
 Wire Wire Line
 	13500 2900 13500 3650
 Wire Wire Line
@@ -4025,4 +4021,10 @@ F 3 "~" H 3400 10750 50  0001 C CNN
 	1    3400 10750
 	1    0    0    -1  
 $EndComp
+Text Notes 11800 9900 0    58   ~ 12
+PCB Errata:\n- R302 (R102 on PCB) has pins 1 and 3 swapped. Connect R305 (R105) directly to the left\n   potentiometer pin!\n- The ground plane at the headphone mix potentiometers is not connected to the remaining\n   ground plane/ power input. Place a jumper manually!
+Text Notes 4650 3750 0    50   ~ 0
+DNP R312 and\nreplace C309 with\na jumper!
+Text Notes 8000 10200 0    50   ~ 0
+Bridge V_LED to +15V\n(5V V_LED didn’t work)
 $EndSCHEMATC

schematics/c3lingo_unit-assembly/c3lingo_unit-mix_io/c3lingo_unit-mix_io.sch

@@ -5,10 +5,10 @@ $Descr A4 11693 8268
 encoding utf-8
 Sheet 2 5
 Title "c3lingo interpeter unit -- mix and line I/O"
-Date "2021-05-28"
+Date "2021-09-02"
-Rev "v0.2"
+Rev "v0.2.1"
 Comp "Jannik Beyerstedt (jtbx)"
-Comment1 "Prototype 1"
+Comment1 "Prototype 1 (with errata)"
 Comment2 ""
 Comment3 ""
 Comment4 ""
@@ -515,7 +515,7 @@ L Device:C C206
 U 1 1 604659B0
 P 5950 4050
 F 0 "C206" V 5698 4050 50  0000 C CNN
-F 1 "1uF" V 5789 4050 50  0000 C CNN
+F 1 "100nF" V 5789 4050 50  0000 C CNN
 F 2 "Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P5.00mm" H 5988 3900 50  0001 C CNN
 F 3 "~" H 5950 4050 50  0001 C CNN
 	1    5950 4050
@@ -526,7 +526,7 @@ L Device:C C209
 U 1 1 60444365
 P 5950 4950
 F 0 "C209" V 5698 4950 50  0000 C CNN
-F 1 "1uF" V 5789 4950 50  0000 C CNN
+F 1 "100nF" V 5789 4950 50  0000 C CNN
 F 2 "Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P5.00mm" H 5988 4800 50  0001 C CNN
 F 3 "~" H 5950 4950 50  0001 C CNN
 	1    5950 4950

schematics/c3lingo_unit-assembly/kicad-libraries/c3lingo_unit-footprints.pretty/Potentiometer_Alps_RK09K_Single_Vertical-patched.kicad_mod

@@ -0,0 +1,41 @@
+(module Potentiometer_Alps_RK09K_Single_Vertical-patched (layer F.Cu) (tedit 6131142B)
+  (descr "Potentiometer, vertical, Alps RK09K Single, http://www.alps.com/prod/info/E/HTML/Potentiometer/RotaryPotentiometers/RK09K/RK09K_list.html")
+  (tags "Potentiometer vertical Alps RK09K Single")
+  (fp_text reference REF** (at 6.05 -10.15) (layer F.SilkS)
+    (effects (font (size 1 1) (thickness 0.15)))
+  )
+  (fp_text value Potentiometer_Alps_RK09K_Single_Vertical-patched (at 6.05 5.15) (layer F.Fab)
+    (effects (font (size 1 1) (thickness 0.15)))
+  )
+  (fp_line (start 13.25 -9.15) (end -1.15 -9.15) (layer F.CrtYd) (width 0.05))
+  (fp_line (start 13.25 4.15) (end 13.25 -9.15) (layer F.CrtYd) (width 0.05))
+  (fp_line (start -1.15 4.15) (end 13.25 4.15) (layer F.CrtYd) (width 0.05))
+  (fp_line (start -1.15 -9.15) (end -1.15 4.15) (layer F.CrtYd) (width 0.05))
+  (fp_line (start 13.12 -7.521) (end 13.12 2.52) (layer F.SilkS) (width 0.12))
+  (fp_line (start 0.88 0.87) (end 0.88 2.52) (layer F.SilkS) (width 0.12))
+  (fp_line (start 0.88 -1.629) (end 0.88 -0.87) (layer F.SilkS) (width 0.12))
+  (fp_line (start 0.88 -4.129) (end 0.88 -3.37) (layer F.SilkS) (width 0.12))
+  (fp_line (start 0.88 -7.521) (end 0.88 -5.871) (layer F.SilkS) (width 0.12))
+  (fp_line (start 9.184 2.52) (end 13.12 2.52) (layer F.SilkS) (width 0.12))
+  (fp_line (start 0.88 2.52) (end 4.817 2.52) (layer F.SilkS) (width 0.12))
+  (fp_line (start 9.184 -7.521) (end 13.12 -7.521) (layer F.SilkS) (width 0.12))
+  (fp_line (start 0.88 -7.521) (end 4.817 -7.521) (layer F.SilkS) (width 0.12))
+  (fp_line (start 13 -7.4) (end 1 -7.4) (layer F.Fab) (width 0.1))
+  (fp_line (start 13 2.4) (end 13 -7.4) (layer F.Fab) (width 0.1))
+  (fp_line (start 1 2.4) (end 13 2.4) (layer F.Fab) (width 0.1))
+  (fp_line (start 1 -7.4) (end 1 2.4) (layer F.Fab) (width 0.1))
+  (fp_circle (center 7.5 -2.5) (end 10.5 -2.5) (layer F.Fab) (width 0.1))
+  (fp_text user %R (at 2 -2.5 90) (layer F.Fab)
+    (effects (font (size 1 1) (thickness 0.15)))
+  )
+  (pad 1 thru_hole circle (at 0 -5) (size 1.8 1.8) (drill 1) (layers *.Cu *.Mask))
+  (pad 2 thru_hole circle (at 0 -2.5) (size 1.8 1.8) (drill 1) (layers *.Cu *.Mask))
+  (pad 3 thru_hole circle (at 0 0) (size 1.8 1.8) (drill 1) (layers *.Cu *.Mask))
+  (pad "" np_thru_hole circle (at 7 -6.9) (size 4 4) (drill 2) (layers *.Cu *.Mask))
+  (pad "" np_thru_hole circle (at 7 1.9) (size 4 4) (drill 2) (layers *.Cu *.Mask))
+  (model ${KISYS3DMOD}/Potentiometer_THT.3dshapes/Potentiometer_Alps_RK09K_Single_Vertical.wrl
+    (at (xyz 0 0 0))
+    (scale (xyz 1 1 1))
+    (rotate (xyz 0 0 0))
+  )
+)