How to cut power to R+L speakers - When current in 3 other circuits?

Thread Starter

aid545

Joined Jul 10, 2017
11
Hi,


Can anyone show on a drawing/schematic how I would wire up the following:

I have 3 wires going to a soundboard (normally no current flowing)

When a current is applied to any of the 3 wires, it plays a corresponding audio message on the sound board

I want the power in the left and right speakers from the main boat stereo system to turn off for for the time the current is flowing in either of the 3 wires (so I can hear the soundboard audio), and the power to return to the stereo speakers when current in 3 wires stops flowing.

I think SPDT Relay is the way to do this .. just not sure what type of SPDT Relay would be needed or what to wire to what terminals.


Thanks so much for any advice.
 

Thread Starter

aid545

Joined Jul 10, 2017
11
hi crutschow .. i think the voltage applied to the soundboard input is 12v.

Soundboard : https://www.adafruit.com/product/2220


The setup is :

GPS tracking unit (powered by 12v battery)
GPS tracking unit has 3 output wires
When certain conditions occur the GPS unit turn's on current in one of the 3 output wires
The output wire activates audio on soundboard
The current continues to output as long as conditions exist


Below is specs from GPS unit I/O (not sure if that means 150ma on output?):

Digital Inputs : 3 (1 fixed, 2 programmable bias)
1-Wire™ Interface : 1 (driver ID, temperature sense)
Digital Outputs : 3 open collector (150mA)
Analog Input : 1 External ADC input
Status LEDs : 2 (GPS and Cellular)
Serial Interface : Serial port (TTL Level)
 

wayneh

Joined Sep 9, 2010
17,496
You need an audio mixer that can mute one signal A when a signal B is detected. It's done at the line-level output of the soundboard and whatever the input to your stereo is normally. I've seen such a thing but can't recall where. :(
 

Thread Starter

aid545

Joined Jul 10, 2017
11
You need an audio mixer that can mute one signal A when a signal B is detected. It's done at the line-level output of the soundboard and whatever the input to your stereo is normally. I've seen such a thing but can't recall where. :(
The soundboard has its own amp and speaker. Is an audio mixer still what is needed?

Anyone know how I can achieve this with SPDT Relay (s)

Thanks
 

crutschow

Joined Mar 14, 2008
34,285
If the 3 wires actually have 12V when active then you could use a 12V coil DPDT relay with a 1N400x diode (x is any number from 1 through 7) from each of the 3 wires to the coil (cathode to coil).
The other end of the coil goes to circuit common (ground).
Also add a diode across the relay coil (cathode to where the other three diodes are connected) to suppress inductive transients.
 
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