EDC-MUX-Board

This is part of the EDC harness project and provides, audio and PTT routing and control routing.

Will also potentially allow for audio priority ducking via the mixer.

All audio IO is done at consumer line level. (IO direction is referenced to MUX)

Connected headphones will accept this as there is also an integrated amplifier. (Headset output)

Connected phones and radios inputting audio into the mux will also work fine as they output line level. (Device input)

Electret microphones need a bias circuit and a preamp to boost their signal up to line level. (headset input) as well as a capacitor to block the DC bias output

Connected phones and radios will need a pad circuit to reduce the line level output to a microphone input as well as block dc output from phone/radio. (Device Output) Resistor divider with ~40dB attenuation. Attenuation in dB = 20* log10((R1 + R2)/R2). Also need resistance between bottom two sleeve contacts.

o-----^v^v^v--|---o R1 > Line < mic R2 > > o-------------|---o

Extra parts

• EN3P8MCX switchcraft 8pin male panel mount connectors (use MPX 3d model)
• EN3C8FCX switchcraft 8pin female cable connection
• CARAEN3C8F07990 switchcraft 8pin female right angle pre-terminated cable
• EN3CAPC cord plug connector cover
• EN3CAPX panel mount connector cover
• 772-E25-103RYY1 norcomp db25 IP67 connector male
• 772-E25-203RYY1 norcomp db25 IP67 connector female (for panelmount)
• 967-025-010R011 norcomp db25 IP67 backshell for cable
• SFP6725 norcomp adhesive seal db25 size
• 967-025-CAP norcomp ip67 sealing cap
• 160-067-004R034 norcomp db25 hardware kit
• 767KS1(X) 0.084 [2.1] id/od sealed locking power plug switchcraft
• L722AS 0.08 [2.0] id/od sealed locking power jack switchcraft (these sizes are compatible with high amperage version
• JCAP power jack cover
• 35FM3AULS - Sealed locking 3.5mm panel mount jack switchcraft
• 35HDLBAU(S) 3.5mm sealed locking plug switchcraft (S=0.175 diameter cable, no S=0.29 diameter cable)
• NE8FDX-P6-W IP rated ethercon connector Cat6A shielded neutrik
• NE8MX6 Cat6A ethercon cable connector neutrik

TODO

• CODE
• Case
  • Change lid screws to M2.5
  • Move Oring inside screw line (use same as on portable line mixer)
  • weight reduction on chassis and lid. Shrink wall thickness to 0.125", leave ribs on base for stiffness
  • leave sealing flange and ribs on lid
  • leave connector sides full thickness

Power Consumption

Quantity	Description	Part Number	Individual Power Consumption
3	IO expanders	TCA9555	56uA @5V
6	IO expanders	TCA9555	35uA @2V5
24	8:1 Mux	ADG708	1uA max @±2V5 (both rails)
8	8:1 Mux	ADG708	1uA max @5V
3	SPST switch	ADG715	25uA max @±2V5 (both rails)
4	4x SPDT switches	ADG734	1uA max @±2V5 (both rails)
72	4x op amp	OPA1604	2.8mA @±12VA (both rails)
21	2x op amp	OPA1602	2.6mA @±12VA (both rails)
12	2x digi pot	DS1882	1uA @5VD, 2.5uA @±5VA
2	OR gate	SN74ACT32	20uA @5V
2	SPST switch	TS12A44514	0.2uA @12V
Total	±2V5 rail		313uA (rounded ->) 0.5mA
Total	±12VA rail		256.2mA (rounded ->) 500mA
Total	±5VA rail		30uA
Total	+5V rail		2*2V5* 0.5mA = 2.5mW @5V = 0.5mA (assume at least 10mA) + 2*5VA* 30uA = 0.3mW @5V = 60uA (assume at least 10mA) + 228uA -> 0.5mA Sum = 0.5mA + 0.5mA + 60uA = 1.06mA (assume 30mA) = 6mA @12V
Total	12V+12VA rail		518.4mA (rounded ->) 1A (includes 2v5 and 5V conversions)

References

• http://www.epanorama.net/circuits/line_to_mic.html
• http://www.n1gy.com/headset-adaptor.html
• http://www.mobilinkd.com/category/hacking/
• http://ham.stackexchange.com/questions/5244/2-pin-kenwood-to-sound-card-beofeng-uv-82hp-asus-xonar-essence-stx
• http://uuki.kapsi.fi/dl/uv5r_spkmic.pdf
• http://www.n1gy.com/headset-adaptor-for-kenwood--baofeng-and-wouxun-hts.html
• http://electronics.stackexchange.com/questions/71335/how-to-amplify-electret-microphone-to-range-from-0-5v-with-bias-of-2-5v
• https://www.invensense.com/wp-content/uploads/2015/02/Using-a-MEMS-Microphone-in-a-2-Wire-Microphone-Circuit.pdf
• http://www.brenorbrophy.com/HG/head_set_ptt.htm
• http://electronics.stackexchange.com/questions/25229/do-electret-condenser-microphones-require-phantom-power
• http://electronics.stackexchange.com/questions/27452/coupling-electret-microphone-input-to-linear-audio-output?rq=1
• http://electronics.stackexchange.com/questions/261258/electret-microphone-how-does-it-work?rq=1
• https://forums.radioreference.com/radio-direction-finding-forum/297920-baofeng-foxhunt-transmitter.html
• https://www.reddit.com/r/amateurradio/comments/2jd4wr/line_level_to_high_impedance_input/
• http://electronics.stackexchange.com/questions/176941/microphone-connection-diagram
• http://i.stack.imgur.com/BMmRJ.jpg
• http://www.dotmana.com/weblog/wp-content/uploads/Kenwood-Ham-Speaker-Jack-Wiring-Schematic.png
• http://forums.qrz.com/index.php?threads/aprsdroid-cable-for-rx-and-tx-on-baofeng-hts.486407/
• http://n4ser.org/2015/aprs-tracker-the-project-phase-2-io/
• http://ham.stackexchange.com/questions/5023/mic-ground-vs-ground
• http://www.circuitbasics.com/how-to-hack-a-headphone-jack/
• http://www.faberacoustical.com/forum/index.php/topic,123.0.html
• http://electronics.stackexchange.com/questions/38452/electronic-aspects-of-iphone-3-5mm-audio-output
• http://www.echoireland.com/Interface/PTT_to_Computer_Information.pdf
• http://electronics.stackexchange.com/questions/22486/help-with-ptt-circuit-for-icom-radio
• http://electronics.stackexchange.com/questions/176442/what-is-the-wiring-for-a-pull-down-resistor-on-the-or-gate