jannik/c3lingo-interpreter-unit
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Main: Summing design flaw fixed; better headphone vol. range

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- Multiple R and C value adaptions
- Line Input: No relevant difference between INA134 and own circuit -> LM833 chosen
- Signal busses/ summing module inputs fixed
- TODO: On-Air Button
- TODO: Update PCB layout
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Jannik Beyerstedt 2020-12-13 22:02:02 +01:00
parent fc7e1fbc8b
commit d8e0d7cb9f
6 changed files with 2722 additions and 3160 deletions
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96
README.md
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@ -42,9 +42,9 @@ This results in a signal flow like this: ![](docs/signal-flow.jpg)
### Tasks ### Tasks
- [x] Requirements collection - [x] Requirements collection
- [ ] Electrical design draft/ proof of concept (breadboard) - [x] Electrical design draft/ proof of concept (breadboard)
- [ ] Proof of concept validation - [x] Proof of concept validation
- [ ] First PCB layout - [x] First PCB layout
- [ ] More testing/ validation - [ ] More testing/ validation
Help is always appreciated! Help is always appreciated!
@ -55,7 +55,7 @@ Help is always appreciated!
- [x] Microphone summing and line output driver - [x] Microphone summing and line output driver
- [x] Adjustable headphone mix and output volume - [x] Adjustable headphone mix and output volume
- [ ] ESD protection and galvanic isolation of line inputs and outputs - [ ] ESD protection and galvanic isolation of line inputs and outputs
- [ ] VU meter - [x] VU meter (own PCB)
- [ ] Mute and On-Air buttons - [ ] Mute and On-Air buttons
@ -76,8 +76,6 @@ But in our case we just need on/ off and some gain range to adjust for different
TODO: Integrate the On-Air button with it's LEDs TODO: Integrate the On-Air button with it's LEDs
For long-lasting endurance of the microphone level potentiometer, we're using one with conductive plastic as resistor element (Bourns model 91).
#### Line Input/ Input Module #### 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. The line input must not be amplified at all, because loudness control of the headphones is done by the headphone amplifier section.
But the differential line-level signal must be converted to a single-ended signal by the input stage. But the differential line-level signal must be converted to a single-ended signal by the input stage.
@ -87,14 +85,18 @@ The second part of that circuit was taken from the [circuitlib audio mixer tutor
TODO: How to achieve galvanic isolation? TODO: How to achieve galvanic isolation?
TODO: Use https://www.ti.com/product/INA134 for input conversion?
#### Summing #### Summing
Summing is needed in two places: Creating the sum of all microphones (not adjustable, fixed output gain) and for the headphone mix (one input level adjustable). Summing is needed in two places: Creating the sum of all microphones (not adjustable, fixed output gain) and for the headphone mix (one input level adjustable).
A simple summing circuit using one operational amplifier is enough for our application, like in [circuitlib audio mixer tutorial](https://www.circuitlib.com/index.php/tutorials/product/39-how-to-build-an-audio-mixer). A simple summing circuit using one operational amplifier is enough for our application, like in [circuitlib audio mixer tutorial](https://www.circuitlib.com/index.php/tutorials/product/39-how-to-build-an-audio-mixer).
The mixer design uses inverting op-amp circuits, because they require less components and signal routing.
Normally an audio mixer should take care of adding signals in-phase, because otherwise two microphones might cancel each other out.
In our case, there are just two types of summing: All microphones for the interpreter unit's line-out and the individual headphone mixes.
Because the stage input is quite independent of the interpreter's microphones, no special phase/ inversion considerations are needed.
And the microphones connected to our unit will experience the same inversions anyways.
#### Line Output Driver #### Line Output Driver
TODO: Either use https://www.ti.com/product/DRV134 or http://www.thatcorp.com/1600-series_Balanced_Line_Driver_ICs.shtml. Line Output conversion is done by the [DRV134](https://www.ti.com/product/DRV134) IC.
TODO: How to achieve galvanic isolation? TODO: How to achieve galvanic isolation?
@ -104,8 +106,17 @@ The headphone output needs a maximum output power of about 0.1 W and should put
For the first draft, we're using one LM386 audio power amplifier even though it has a quite high minimal amplification of factor 20. For the first draft, we're using one LM386 audio power amplifier even though it has a quite high minimal amplification of factor 20.
#### VU Meter #### VU Meter
Because the LM3916 LED bar graph driver is obsolete, we either have to re-create it's function with some comperators or have to use a microcontroller. When searching for VU meter circuits, many use the LM3916 LED bar graph driver, which already has the right scaling built in.
But this chip is obsolete and not produced any more, so we designed our own chain of comperators to drive a set of LEDs.
#### User Interface Hardware
For the potentiometers, we first wanted to use ones with a conductive plastic resistor element for maximum longevity from Bourns, but these are hard to find with logarithmic scaling.
An affordable and easily obtainable (Reichelt) alternative was found in the Alps RK11K and RK14K series.
They are available in linear and logarithmic scale, as well as single (mono) and dual (stereo) units and have a nice feeling.
Another potentiometer from Omeg was tried, but it had a "jump" in the resistor value at some knob positions.
TODO: On-Air button
## Notes ## Notes
@ -122,18 +133,65 @@ Approximate prices in Euro.
Connectors and Buttons (User Interface) Connectors and Buttons (User Interface)
| Count | Art. No. | Description | Price | | Count | Art. No. | Description | Price |
|-------|--------------------|------------------|-------| |-------|---------------------|---------------------|-------|
| 1 | Neutrik NCJ 6 FAH | Line Input | 1,27 | | 1 | Neutrik NAC3 MPA-1 | Main Power Input | 3,33 |
| 1 | Neutrik NC3 FD-LX | Microphone Input | 3,44 | | 1 | Neutrik NCJ 6 FAH | Line Input | 1,27 |
| 1 | Neutrik NJ3 FP-6-C | Headphone Output | 5,40 | | 1 | Neutrik NC3 MD-LX | Line Output | 3,22 |
| 1 | Neutrik NC3 MD-LX | Line Output | 3,22 | | 1 | | | TODO |
| 1 | Neutrik NAC3 MPA-1 | Main Power Input | 3,33 |
| 3x1 | Neutrik NC3 FD-LX | Microphone Input | 3,44 |
| 3x1 | Neutrik NJ3 FP-6-C | Headphone Output | 5,40 |
| 3x1 | TODO | Mute Button | TODO |
| 3x1 | TODO | On-Air Button | TODO |
| 3x4 | Alps RK11K1120-A503 | 50K log. Gain/ Vol. | 1,32 |
| 3x1 | Alps RK14K12B0A0R | 50K log. Vol. (st.) | 1,50 |
| 1 | Vishay M64{Y,Z}104 | 100K Trim Pot. | 0,95 |
Sub-Components Sub-Components
| Count | Art. No. | Description | Price | | Count | Art. No. | Description | Price |
|-------|--------------------|------------------|--------| |-------|---------------------|---------------------|-------|
| 1 | Traco Power TXL 035-1515D or TOP 60533 | Power Supply | ~48,00 | | 1 | Traco Power TXL 035-1515D or TOP 60533 | Power Supply | ~48,00 |
PCB Components: TODO when schematic is finished PCB Components: TODO when schematic is finished
| Count | Art. No. | Description | Price |
|-------|---------------------|---------------------|-------|
| 3 | NE5534 | Low-noise Op-Amp | 0,54 |
| 8 | LM833 | Generic Op-Amp | 0,88 |
| 3 | LM386N-4 | Audio Power Amp | 0,83 |
| 1 | DRV143 | Line Driver | 4,50 |
| TODO | TODO | El. Capacitor | TODO |
| TODO | TODO | Cer. Capacitor | TODO |
| TODO | TODO | Resistor | TODO |
VU Meter Components
| Count | Art. No. | Description | Price |
|-------|---------------------|---------------------|-------|
| 1 | Vishay M64{Y,Z}104 | 50K Trim Pot. | 0,95 |
| 1 | LM833 | Generic Op-Amp | 0,88 |
| 2 | 1N4148 | Signal Diode | 0,02 |
| 1 | 1k Metal Film | Resistor | TODO |
| 1 | 3.9k Metal Film | Resistor | TODO |
| 1 | 47 uF | El. Capacitor | TODO |
| 1 | 100k Metal Film | Resistor | TODO |
| 3 | LM339 | Quad-Ch. Comperator | 0,29 |
| 5 | 100 nF | Cer. Capacitor | TODO |
| 1 | 1 uF | El. Capacitor | TODO |
| 5 | Vishay TLHR 5404 | LED red | 0,18 |
| 4 | Vishay TLHY 5404 | LED yellow | 0,14 |
| 3 | Vishay TLHG 5404 | LED green | 0,17 |
| 12 | 390R | Resistor | TODO |
| 1 | 39R | Resistor | TODO |
| 2 | 68R | Resistor | TODO |
| 1 | 100R | Resistor | TODO |
| 1 | 150R | Resistor | TODO |
| 1 | 270R | Resistor | TODO |
| 1 | 390R | Resistor | TODO |
| 1 | 680R | Resistor | TODO |
| 1 | 1K | Resistor | TODO |
| 1 | 1.5K | Resistor | TODO |
| 2 | 2.7K | Resistor | TODO |
| 1 | 3.9K | Resistor | TODO |

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c3lingo-mixer.pdf
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schematics/mixer/c3lingo-interpreter-unit-cache.lib
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@ -360,53 +360,6 @@ X VO+ 8 1600 150 300 L 59 59 1 1 O
ENDDRAW ENDDRAW
ENDDEF ENDDEF
# #
# JBeyerstedt-Library_INA134PA
#
DEF JBeyerstedt-Library_INA134PA U 0 10 Y Y 1 F N
F0 "U" 800 500 60 H V C CNN
F1 "JBeyerstedt-Library_INA134PA" 800 400 60 H V C CNN
F2 "Package_DIP:DIP-8_W7.62mm" 800 340 60 H I C CNN
F3 "" 0 -200 60 H I C CNN
$FPLIST
P8
$ENDFPLIST
DRAW
S 300 300 1300 -900 0 1 0 N
X REF 1 0 -750 300 R 59 59 1 1 W
X IN- 2 0 -200 300 R 59 59 1 1 I
X IN+ 3 0 -450 300 R 59 59 1 1 I
X V- 4 1600 -750 300 L 59 59 1 1 W
X SENSE 5 1600 -200 300 L 59 59 1 1 I
X OUTPUT 6 1600 -450 300 L 59 59 1 1 O
X V+ 7 1600 150 300 L 59 59 1 1 W
X NC 8 0 150 300 R 59 59 1 1 N
ENDDRAW
ENDDEF
#
# Jumper_Jumper_3_Bridged12
#
DEF Jumper_Jumper_3_Bridged12 JP 0 0 Y N 1 F N
F0 "JP" -100 -100 50 H V C CNN
F1 "Jumper_Jumper_3_Bridged12" 0 110 50 H V C CNN
F2 "" 0 0 50 H I C CNN
F3 "" 0 0 50 H I C CNN
$FPLIST
Jumper*
TestPoint*3Pads*
TestPoint*Bridge*
$ENDFPLIST
DRAW
A -65 -50 89 1282 518 0 1 0 N -120 20 -10 20
C -130 0 20 0 0 0 N
C 0 0 20 0 0 0 N
C 130 0 20 0 0 0 N
P 2 0 1 0 0 -50 0 -20 N
X A 1 -250 0 100 R 50 50 1 1 P
X C 2 0 -150 100 U 50 50 1 1 I
X B 3 250 0 100 L 50 50 1 1 P
ENDDRAW
ENDDEF
#
# Switch_SW_Push # Switch_SW_Push
# #
DEF Switch_SW_Push SW 0 40 N N 1 F N DEF Switch_SW_Push SW 0 40 N N 1 F N

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schematics/mixer/c3lingo-interpreter-unit.kicad_pcb
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schematics/mixer/c3lingo-interpreter-unit.pro
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@ -1,4 +1,4 @@
update=Thursday, 12 November 2020 at 23:33:32 update=Sunday, 13 December 2020 at 21:49:58
last_client=kicad last_client=kicad
[general] [general]
version=1 version=1
@ -242,7 +242,7 @@ dPairViaGap=0.25
[schematic_editor] [schematic_editor]
version=1 version=1
PageLayoutDescrFile= PageLayoutDescrFile=
PlotDirectoryName= PlotDirectoryName=../../
SubpartIdSeparator=0 SubpartIdSeparator=0
SubpartFirstId=65 SubpartFirstId=65
NetFmtName=Pcbnew NetFmtName=Pcbnew

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schematics/mixer/c3lingo-interpreter-unit.sch
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