Have ben working on a DIY stereo here and there in some spare moments and need some advice / help on making a small audio selection and volume circuit. This circuit will Ideally be controlled by a I2C or similar and struggling to find something suitable.
The internals are simply a chipamp.com stereo amplifier, plus a raspberry pi with a DAC hat, but I want to be able to have 2 or 3 pairs of RCA connectors to add other audio sources (record player etc) and to be able to switch between them via a web interface / raspPi. Same for volume with a digital pot.
My only issue with the MAX audio selectors is that they all come in tiny packages (TQFN)
My questions are - should I stick with the MAX audio selectors and try and make the PCB with a reflow oven of some kind or is this too ambitious given its tiny so so tiny pin out?
If not, any one know of an audio selector IC in a bigger package?? I’ve searched high and low but to little avail.
Also, I’ve not designed many (read ‘any’) circuits or PCBs, so any pointers on what resistors / caps to put on the pins of these things is appreciated
The big problem with pcbs is the package i use is old and i can’t be bothered to learn or buy a new one so you will might have to get use to a 1998 package
If I am reading your post right you might be able to use an analogue multiplexer IC like a 4051. This gives 8 inputs to 1 output, selected by a 3 bit input code (3 pins).
The datasheet below gives full particulars and the truth table for the output selection:-
The HEF4051B looks like it only has one output so I don’t think supports stereo, thanks though.
I did see mentions of a 4066 but didn’t follow up, but the CD4066BC looks great, I’ll try make it down tomorrow evening @joeatkin2, had the flu but its gone now, see if we can figure it out Think I’m going to try and learn Eagle…
If you want a high quality switch with less than 4 inputs the 4066 is the best bet and for more than 4inputs the 4051 and 4066 combination would work but you will have to do click supresion in software.
It takes 4 gates to switch a single audio line in high quality audio or 3and a inverter , plus a hand full of risistors and capacitors to control edge speed .you could get away with two and a inverter in a amp input but definitely 3 for a mixer .
The big advantage of desceat gates is the ability to control the edge speed and the switching sequence
The problem with cmos switchs is that they are not perfect switchs , but if you switch to a virtual ground it cercomnavigats the bulk of the problems
Think I’m going to try and learn Eagle…