Sarah said:
Hello everyone:
I'm looking for a schematic for a audio combiner that has a mute or cut-out
that mutes the non priority input when the priority input has voltage. I
want to make an audio combiner to listen to music from a CD Player in a
aircraft with my headset. I want to have the signal from the CD player cut
out when I have a transmission coming in over the aircraft radio.
Thanks in advance to anyone that can help.
Rob Gagné
[email protected]
You want an adaptation of something traditionally called a VOX or
Voice-Operated-Switch. The "voice" activation will be from your primary
audio channel, and the switch will turn off the entertainment audio and
connect the primary channel to the headset- this can be done with a reed
relay or analog mux. A sample schematic using the MC2830 is shown here:
http://www.electronics-lab.com/projects/sensors/025/ - looks like the
2803 is obsolete. A simple starting point would be this kit- made in
your neck of the woods:
http://www.canakit.com/Default.asp?...tp://www.canakit.com/Contents/Items/CK257.asp
You adapt this by 1) remove that MIC and replace with attenuator
driven by your primary audio channel, 2) remove that big power hungry
relay and replace with transistor open collector output, 3) add daughter
board with 1) two input jacks for primary and entertainment audio, 2)
reed relay or analog mux, 3) output jack for headset, 4) power supply
terminals. Line this daughterboard up with the corner holes on the kit
board and mount- drop in a box. The plan would basically look like this:
Please view in a fixed-width font such as Courier.
ATTENUATOR
PRIMARY >---+-/\/\--+--/\/\---||---> TO MIC INPUT VOX
AUDIO CH | |
| /
| \
| /
| \
| |
GND----------------+---------------GND
|
12VDC----------------------+---------12VDC
| |
| |
| REED RELAY |
+--- o |
o--------------> HEADSET
|/ |
SECONDARY>--------o - |
AUDIO CH |
------ |
+---UUUUUU--+
| |
+-----|>|---+
|
+--------------------< SW OUTPUT FROM VOX