What an elegant solution, using "old" CMOS technology. A timely reminder for me that some things are better achieved without "having to" use a MCU. Thanks & cheers.
Thank you for the comment Neville. The circuit was behaving quite strangely until I tied pins 5 and 13 to ground!
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Hi! thank you very much for the video, I think it will be very useful for my project of audio switch between two automatic computers. Thank you very much!
Do you hear any popping as you switch on low level signals just out of interest? As there is 3.4V on input before switching and 2.61V after it's switched. Not sure what the ON impedance of the switch is so have ignored it. just looked it up but at around 10 ohms it's not going to make a difference. this can be a problem if you have more than one vertual grounds in an audio design, as you switch from one to the other the difference comes out as a pop. can be worse if the amplifier gain causes the speaker cone to try and exceed its limits. Keep the video's coming it gives the old grey cells a work out.
There's definite popping in the output. I am pretty sure its due to that biasing arrangement. I might try doing a resistor divider setup on both switch input and output and see if that does anything. Thank you for the comment TEH! On the on resistance I see both 125 ohms @ 15V (right at the top in features) and later in the datasheet 10 ohms - not sure which is the right figure
@@na5y Had another look at the data sheet and the 15 ohm is for the Ron delta between channels. my bad. Page 7 gives the Ron @25°C as 470 to 1050 ohms with a 5V supply. dropping down to 125 ohms at 15V. the 470 might help reduce the popping, but any change in dc is a fast AC signal, can be too fast to hear but the result of maybe hitting the the rails can be heard.
Not quite sure what VDD I would have to run the CD4066 in my radio. I will have to measure the audio levels from after the pMod board just before the speaker - that would be the highest. Interestingly though if I run fully headless with streaming in/out audio over wifi I wouldn't even have to worry about pMod -> Speaker and Microphone -> pMod
@@na5y So now the DC potential across the switch is very small, so the affect on charging and discharging the caps is small so now a quiet switch action. Used these a lot with lm741's in avionic audio control with 8080 chips for control. just befor we switched to full TDM digital control, leaving only the emergency audio com's with an analogue signal path as a back up.
What an elegant solution, using "old" CMOS technology. A timely reminder for me that some things are better achieved without "having to" use a MCU. Thanks & cheers.
Thank you for the comment Neville. The circuit was behaving quite strangely until I tied pins 5 and 13 to ground!
Hi! thank you very much for the video, I think it will be very useful for my project of audio switch between two automatic computers. Thank you very much!
Thank you Jairo. Since that video I played around with using the FST3253 as audio switch. Have a look here
ruclips.net/video/d4cmGwFpQcw/видео.html
Do you hear any popping as you switch on low level signals just out of interest? As there is 3.4V on input before switching and 2.61V after it's switched. Not sure what the ON impedance of the switch is so have ignored it. just looked it up but at around 10 ohms it's not going to make a difference. this can be a problem if you have more than one vertual grounds in an audio design, as you switch from one to the other the difference comes out as a pop. can be worse if the amplifier gain causes the speaker cone to try and exceed its limits.
Keep the video's coming it gives the old grey cells a work out.
There's definite popping in the output. I am pretty sure its due to that biasing arrangement. I might try doing a resistor divider setup on both switch input and output and see if that does anything. Thank you for the comment TEH!
On the on resistance I see both 125 ohms @ 15V (right at the top in features) and later in the datasheet 10 ohms - not sure which is the right figure
@@na5y Had another look at the data sheet and the 15 ohm is for the Ron delta between channels. my bad.
Page 7 gives the Ron @25°C as 470 to 1050 ohms with a 5V supply. dropping down to 125 ohms at 15V.
the 470 might help reduce the popping, but any change in dc is a fast AC signal, can be too fast to hear but the result of maybe hitting the the rails can be heard.
Not quite sure what VDD I would have to run the CD4066 in my radio. I will have to measure the audio levels from after the pMod board just before the speaker - that would be the highest. Interestingly though if I run fully headless with streaming in/out audio over wifi I wouldn't even have to worry about pMod -> Speaker and Microphone -> pMod
I just tried with a 10k/10k resistor divider on switch input *and* output and the pops disappeared entirely.
@@na5y So now the DC potential across the switch is very small, so the affect on charging and discharging the caps is small so now a quiet switch action. Used these a lot with lm741's in avionic audio control with 8080 chips for control. just befor we switched to full TDM digital control, leaving only the emergency audio com's with an analogue signal path as a back up.
Thank you very much!
You are welcome Jozef!
Super cool
Thank you Stephen!
dear sir , i like to switch balanced XLR audio signal ( hot and cold ) i required 20ch audio switch , how can i do that please guide me .