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Custom PCB!

Former Member

Ok so im really really new to all of this sort of stuff but iv need watching Ben Heck for a bit and iv some up with a idea... but i need a little help from people more experienced. So i want to make a device that you can switch 2 audio and 2 microphone inputs and output the audio as a 3.5mm audio jack or RCA or both and output the microphones in one line and or mix both mic's inputs into a single output to then be able to have 2 microphones working and being used and have one microphone recording software record both mic's as one input. I believe i need some sort of microcontroller and a custom PCB for it but im a total noob and all of this.

 

So what im asking is:

What microcontroller would i need?

Do i need to design a schematic to send to a PCB company to build?

 

I have a few images of my planning sheets with my basic idea on it. my writings kinda hard to read for some but if you need help i can image

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The end of the second image reads for the mic button

Mic tog: toggle both mic inputs or select one for single mic use or mixed mic use.

 

the schematic design on the second image isnt a proper schematic its just a idea as i said i dont know anything about this and id like to lean image

  • I'm struggling a bit with your description, especially this bit:

     

    "then be able to have 2 microphones working and being used and have one microphone recording software record both mic's as one input"

     

    is your board doing the recording ?

     

    If not then you don't need a micro because all the signal processing can be analogue.  Sounds as if you need 2 microphone amplifiers, a mixer and some routing. You could do it all digitally but it would be harder.

     

    Can you explain what it's for and the sort of audio quality needed  - then I  might be able to suggest something. You could probably  do all this with a pretty cheap audio  mixer and some leads unless you are keen to actually build it yourself.

     

    MK

  • in reply to michaelkellett

    Ahh I see what i mean is with the device i can have say 2 audio inputs and ill be able to toggle between the 2 from going to the speakers so like my phone and my computer i could toggle them and similar with the microphones, i want to be able to have say 2 microphones plugged in and have a system where i can pick to use either microphone 1 or 2 or "both" where it can mix the 2 signals from the microphones into a single signal for software to use for example, when i make youtube videos with a friend we sit to far away from each other to have only 1 microphone for the 2 of us therefore if i were to have 2 microphones plugged into the unit and it mixes it still appears to the computer as one microphone but in actual fact its 2 microphones having their signals mixed into one for software to record it. i know theres probably devices out there or cheep ways of doing it but i would like to make this unit as a one off thing just to try it out and have a little fun with this stuff, i was also planning to make a USB 3.1 HUB to go with the unit but that seemed to be a little complicated to start off with.

     

    Just overall i want to design a device that can be used as a Audio Switcher/Microphone Switcher/ Microphone mixer and maybe a 4 port USB3 HUB

  • in reply to Former Member

    Decoding that, I think you want  a USB computer audio interface with 2 stero line inputs, 2 microphone inputs, at least one pair of analogue outputs for speakers and the ability to appear to the PC as one microphone. You also mention building in a USB3 hub.

     

    The USB3 hub as nothing to do with the audio and is not something you can readily make yourself - just buy one. You don't need USB3 for audio so the interface thing could be USB2 full speed or high speed.

     

    From what you have said so far I don't think you are ready to attempt digital audio at pcb and chip level - please correct me if I'm wrong.

    The Tascam US-125M USB Mixing Audio Interface nearly does what you want - you'll never build anything as good for the same money so you might like to look at it and similar things both to get ideas and maybe just buy one.

     

    If I were you and really wanted to build something I'd buy a USB digital audio interface and make the analogue  mixer switchy thing myself.

     

     

    MK

  • in reply to michaelkellett

    Yeah i can have a look into that but i really just wanted to try out building a small single unit that i can use for my audio/mic switching and the mic mixing and then have the usb hub built into the bottom or something. the hub would be easy i could just buy a USB hub and stick it in the cause of the audio device and pretty much make little usb extension cables to ports on the front for it to be used but with the audio stuff i didnt really want to go out and get a already made product i really wanted to try out this as a little project for me and maybe a few friends. the plan was to have a small box thats thin enough to sit under computer monitors and have a small LED indication interface on the front displaying the different settings. on the inputs i just wanted the 2 audios and the 2 microphones and maybe a usb for power if it was needed, the outputs i wanted to have a 3.5mm jack for my speakers and a RCA audio output as i myself have a huge miss of cables just making it able to split my computer audio from 3.5mm jack to RCA and back again as well as have the single microphone output. The idea was just to have a little box that doesnt rely on any usb data to be sent between a computer but to use a computer to maybe power the unit for switches and LED's and so one. i know theres probably really cheep devices that do all that but i wanted to have a shot at making my own and then being ablt to then build the case for it.

  • in reply to michaelkellett

    Sorry to add but the Tascam US-125M isnt really what i had in mind thats more of a studio based product where as mine is more of a gamers or youtubers type of product and i explained in my last comment image

  • in reply to michaelkellett

    haha sorry for spamming the replies but im not sure what you were getting when i was saying "microphone" when i have been saying microphone i generally mean the consumer based 3.5mm USB powered microphones similar to say a pair of Turtle Beach x12's where you have a USB for power, 3,5mm male jack for game audio and a 3.5mm male plug for external microphone uses, sorry about the confustion i wasnt meaning like the large 3 pin microphones studios use or anything like that.

  • in reply to Former Member

    Here is about the simplest mixer circuit you will find. Use an MCP6021 for low cost.

     

    image

    The rest of the functionality sounds like it can be implemented with a bunch of toggle switches.

  • in reply to dougw

    thankyou for that image i do have a schematic for the audio switching draw up but i need a little help with the placement of capacitors and resistors go it any are needed.

     

    its not very efficient using 2 switches for Left and Right audio but im new to all this and i dont know how to make the 2 actions happen with one switch....

     

    image

  • in reply to Former Member

    A "double pole double throw" (DPDT) switch will operate both switches at the same time with one lever.

  • in reply to dougw

    This isn't the best way to use a single op amp for mixing - much bertter to use an inverting amplifier configuration so that the two inputs don't interact with each other.

    (BTW the OPA 134 isn't good for single 5V operation - accoridng to data sheet it needs 2.5V headroom on the input from each supply rail and it won't manage much ouput swing either.)

     

    Bryce would be much better off using AD8655 or AD8656 which are specced for rail to rail IO at 5V.

     

    Here's an article (not brilliant but the first one I found) which explains why mixers should use inverting amp configuration and gives some better alternative circuits.

     

    http://www.all-electric.com/schematic/simp_mix.htm

     

    MK