There is quite a comprehensive data sheet on RS Components, if that's any use?
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There is quite a comprehensive data sheet on RS Components, if that's any use?
The best way I've found for "click free" audio switching is to have every connection to the switches capacitor coupled, with every switch connection also having a high value bias resistor back to a common (and well decoupled) mid-supply bias - or 0V bias, if using dual-supply switches.so that the switched audio signals are in the 0-5v range (rail-to-rail) at the switches, so I can't use a decoupling capacitor until after the switch.
The best way I've found for "click free" audio switching is to have every connection to the switches capacitor coupled, with every switch connection also having a high value bias resistor back to a common (and well decoupled) mid-supply bias - or 0V bias, if using dual-supply switches.
Exactly - same concepts, keeping everything mid-range & avoiding jumps in level.If I understand this correctly, then in addition to this biasing approach reducing clicks/pops, it also has the benefit of "normalizing" all the switched audio inputs (each could have been initially biased around different voltage levels), and also conveniently brings them all within the "rail-to-rail" voltage (in my case, 0-5V range) so I can use an analog switch IC.
This whole topic seems someone related to something I did in my tone generating code to minimize "popping" when stopping/starting tone output and changing tones. I always guarantee that my DAC output comes to rest at the mid-point, and never allow any sudden jumps in output:
That's where the balanced audio feed may help - it should cancel out the cross-coupling?so it seems that sudden jumps in analog audio voltage can create enough interference on the digital UART wires to corrupt the data.
Using a star point earth setup may also help.
When I used 0.1 uF for the output as well, I got some strange unwanted echoing/fading "ping" sound if I pressed a button (causing a beep) while I had the volume turned "off" (audio signal input to the digital pot completely disconnected from the internal resistor network).