Hope that someone can help. I’m at an impasse. I am very good at researching and borrowing ideas and changing them to fit my needs. I am a novice at heart who is learning as i go. But as i said i have reached an impasse on my project.
An overview.
I have my PC and i have my alexa. I have one set of speakers and need to physically unplug the 3.5mm jack from the speaker each time i want to swap between devices.
I have bought a couple of things that i thought might help me but end up with a continuous hissing. I have done my research and found out this is probably due to the fact that there is always power going through the cables and a switch only changes the direction of one of the positive or negative cables (i hope this makes some sense). This is the passive options i have tried and I’m not happy with for obvious reasons.
I decided to go down the active route as i feel i will get the best results and closer to what i wanted. So after doing my research i found an indestructible post basically what i wanted. I have tweaked it for my need as i want to use a wemos D1 mini to control it over WIFI with the alexa. (I have had some luck programming these before and had a couple lying around).
I also want to be able to plug a micro usb into it and then pass out another micro usb to power my Alexa. (hence the five pin out put on my design).
I would like to retro fit the passive switch that i have as it’s the perfect size for what i want.
I would like to also add a physical switch (that could send a signal to override the wemos and switch if needed).
My questions are and i hope someone can help me who has a lot more experience.
How and where do i add the switch (it has six positions on it)?
Will my design actually work? (My next step is buying everything i need including bread board).
As i said I’m a complete novice and am only starting to learn. I have no idea about capacitors or resistors. The part I’m enjoying is the research and the design of the PCB (Which i won’t obviously get until i know the project actually works how i want it). I am really looking forward to the physical soldering and manufacture.
Thank you in advance and please ask me any questions. I will try and answer as best i can. I have attached a picture of the circuit diagram i have made (apologies as it was my first) and a picture of the passive box that i already have.
A lot of words and very little useful information. You tried something and it gave you noise so you tried something else unspecified from the internet‘s most unreliable source of information “Instructables”. But no actual real details. The same goes for your required operation, not very clear what you want to do.
I can answer this question however
Will my design actually work?
No it will not. That multiplexer chip will not handle negative voltages nether will the Arduino, and you have negative voltages the instance you put an audio signal through a capacitor.
What information do you need? I thought i covered as much as i could. I also got advice to use bipolar capacitors. Would they not help?
As i have said im just a very keen novice with an idea in my head.
If my idea wont work. What do you suggest? Im open to ideas.
My goal is to be able to swap between two 3.5mm jacks with one output 3.5mm. I would like to be able to control it with the wemos d1 mini over wifi and have the power be able to pass through so i can power my Alexa. I would like a toggle switch so as to be able to physically switch the inputs as well if needed. I would like to be able to do this without any hissing or degrigation.
Who told you this? Are you posting somewhere else as well? I think we should be told.
I have been in the business over 50 years and I have never heard of a bipolar capacitor. Do you mean a none polarised capacitor? The quick answer is that it matters not what type of capacitor you use you always get negative voltages out of a capacitor.
The way round this is to bias the signal to a mid voltage using two resistors.
What information do you need?
Real things, not vague wish washy "I tried something and it didn't work." What did you try?
As i have said im just a very keen novice with an idea in my head.
That is all very well but unless you can get the idea in someone else's head you can't expect any specific help.
My goal is to be able to swap between two 3.5mm jacks with one output 3.5mm.
You might know what that means to you but that means nothing to me. What do you mean by swap?
I would like to be able to do this without any hissing or degrigation.
Reed relays or signal relays would be simple, not require a lot of protection components.
If you want to use a multiplexer then each channel would need to look something like:
The 1k resistors and schottky diodes protect the analog multiplexer chip from excessive voltage swing,
the 10k resistors and 10uF caps shift the level to mid-rail for the analog multiplexer so the signal can
swing both polarities without being clipped, the 1M resistors keep the external wiring at 0V DC so you
don't get a loud click when plugging in a signal wire. 10uF caps assume the ultimate audio load has an
impedance no smaller than a few k ohms. The 1k resistors also would attentuate too much if driving a
low impedance load.
Relays have the advantage of needing no signal conditioning or protection circuitry in the audio path.
[ Ooops, I should have placed the schottky diodes the other side of the 10uF caps, sorry about that! ]
