I'd appreciate a bit of help figuring out a good way (assuming one exists) of routing an audio signal to one of 4 (possibly more) identical output speakers.
Based on my research so far, it seems relays or FETs are two possibilities. I'm thinking of using Arduino digital pins to trigger whichever output is chosen.
The relays example seems almost exactly like what I'm looking for, but I'm confused how to extend the concept to more than 2 outputs.
Could I create a 'tree' circuit using relays? It's unclear to me how the audio signal would pass through a circuit that had multiple relays.
Or perhaps one of these relay shields? http://www.robotshop.com/seeedstudio-arduino-relay-shield.html I see how this easily allows triggering of multiple relays, but I don't understand how audio can pass through.
Before I buy any DPDT relays or anything, I'd just like some idea of whether this might be a good approach. I've used relays + Arduino before, but just as a yes/no switch.
I would suggest relays for minimal loss in your signal, especially if you're routing very small signals (relay contacts are rated in less than a milliohm), vs. FETS or digital switching chips that may be a few ohms to 100ohms or so.
Many ways to skin this cat. You can use DPDT relays, and some decoder chips, so you can control up to 8 relays and selectively turn on/off each or some combination thereof.
Or just connect each relay (and associated NPN transistor driver) directly to a spare Arduino output pin and turn them on/off individually.
Let me know if you want me to draw a block diagram if you can't picture it.
Thanks very much for the reply...it seems that relays are a good option.
I'm interested in controlling some combination of up to 8 relays. What type of chip would this involve? I have some 555 timer chips and the like.
A more simple setup would also work, at least to test the concept.
For a simple arduino-to-relay circuit, I've used this in the past: Arduino Playground - HomePage
What I am having trouble picturing is how the audio signal would fit into any of these circuits. I'd appreciate some additional detail on that.
But I'm still having trouble visualizing what a potential audio switching relay circuit might look like, in terms of where the audio signal is connected. I'd really appreciate being pointed towards a schematic or photo or block diagram of such a circuit.
It seems I could do this either way, using DPDT relays or a multiplexer/demultiplexer.
I'm interested in the power of the demux chip, but I've read that I should beware of noise added to audio signals.
I might just get the components to do both and see which method I prefer.
Just a bit more information about what I'm trying to do:
Arduino will be sending control data to an .mp3 breakout board, and the audio output of that board will be routed through the relay/demux circuit to one of 4 identical surface transducer/exciters, that will be attached to everyday objects and cause them to resonate.
I feel like I'm ready to move forward...
One last question: is there a significant difference between the maxim chips that Magician pointed out and something like a TI 74HC4052?
is there a significant difference between the maxim chips that Magician pointed out and something like a TI 74HC4052?
The difference in this parameter:
Low “On” Resistance
70? Typical (VCC - VEE = 4.5V)
40? Typical (VCC - VEE = 9V)
For myself, I'd not buy maxim, IMHO product highly overpriced. Better to route low level signals, and use multiple PA system. Sparkfun has PA IC with 4 channels for less than 3$
Thanks for the link, Magician.
So you're saying this chip can handle the routing (1 input to any of 4 outputs)?
It seems to be designed as an amp, and the block diagram shows that input x can't go anywhere but output x.
Perhaps I'm being daft.
Better to route low level signals, and use multiple PA system.
You are switching (multiplexing - demultiplex ) line level signals, using cheap and abandon 4051/52/53/66/67 etc CMOS IC, than do amplification. Logic is simple, N x STA540 + 74HC4051 would cost less than 1 x Power Amplifier + N x Maxim low R-on IC
Thanks. You make a good point, but perhaps I should explain my project just a bit more.
The line level signal exit will exit the routing circuit and go to a surface transducer, which will be placed on a piece of glass.
From there, the vibrations of the glass will be picked up using a piezo microphone and put into a mixer and amplifier, and then some speakers (I already have these things).
Perhaps it's a better idea to also amplify the signal before it reaches the transducer, but my tests so far have been ok in terms of amplitude.
