Hi,
I have a simple audio switching circuit that is giving me a problem. I am using a CD40106 Schmitt Trigger in conjunction with a CD4066 CMOS switch to route up to two audio signals between wet & dry circuitry.
The circuit is DC and will run on 9 15 volts. It will always be under 100 mA so were not talking a lot of power.
The circuit works well, except that with an amplifier turned way up I can hear a very small pop in the audio when the circuit gets engaged. I know, most of you think Well turn the amp down dummy! but I am trying to totally isolate all the sound so there is a seamless switch from one state to another.
I know that the issue could be taken care of with pull down resistors or capacitors. However these seem to remove some volume and degrade the sound quality a bit, the goal is to have the volume level that enters the unit match the output volume so I am trying to avoid that route.
I have read that this is due to a split second of Capacitance Coupling into the signal line. I believe that Ramping the control signals voltage up and down a few milliseconds with triangle waves to the CMOS can eliminate the issue but I cannot find an example of how to really implement the concept into my design.
So what do think? Would an Astable Multivibrator creating triangle waves make the difference? And where would it go in the circuit?
Thanks in advance for ALL of you out there helping.
Danny
I have a simple audio switching circuit that is giving me a problem. I am using a CD40106 Schmitt Trigger in conjunction with a CD4066 CMOS switch to route up to two audio signals between wet & dry circuitry.
The circuit is DC and will run on 9 15 volts. It will always be under 100 mA so were not talking a lot of power.
The circuit works well, except that with an amplifier turned way up I can hear a very small pop in the audio when the circuit gets engaged. I know, most of you think Well turn the amp down dummy! but I am trying to totally isolate all the sound so there is a seamless switch from one state to another.
I know that the issue could be taken care of with pull down resistors or capacitors. However these seem to remove some volume and degrade the sound quality a bit, the goal is to have the volume level that enters the unit match the output volume so I am trying to avoid that route.
I have read that this is due to a split second of Capacitance Coupling into the signal line. I believe that Ramping the control signals voltage up and down a few milliseconds with triangle waves to the CMOS can eliminate the issue but I cannot find an example of how to really implement the concept into my design.
So what do think? Would an Astable Multivibrator creating triangle waves make the difference? And where would it go in the circuit?
Thanks in advance for ALL of you out there helping.
Danny
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