pink noodling
Here is a previous blog post on pink noise:
https://wb9kzy.blogspot.com/2023/12/pink-noise-filter.html
Pete, N6QW, sometimes uses the term: noodling on the Soldersmoke podcast when discussing the design of a circuit. As I understand it noodling involves improving a basic circuit through an iterative design change and simulation cycle. This is done prior to building the circuit. I found a video where the presenter "noodles" a white to pink noise filter using LTspice to analyze the results:
source: https://www.youtube.com/watch?v=WkxOJcZEWtU
I learned a lot, not least of which was using LTspice to display frequency response and do measurements automagically.
BTW, I also learned that Dennis Bohn, the author of the Popular Electronics pink noise generator article mentioned in the previous blog post, worked for National Semiconductor (the vendor of the MM5837). He was also the editor of the National Semiconductor Audio Handbook from 1977:
The Audio Handbook mentions the pink noise filter and a little about the design:
https://archive.org/details/NatSemiAudioHdbk1977_201801/page/n3/mode/2up
It also struck me after reading this National Semiconductor Audio Handbook entry on the pink noise filter that there was no reason (in the previous blog post about the pink noise filter) to do the db calculations above 20,000 Hz (the upper frequency limit of hearing). This makes that data look much better.
I also tried simulating the pink noise filter circuit in a spreadsheet (rather awkwardly I'll admit). At each of the octave related frequencies from 20-20,000 Hz the capacitive impedance was calculated and then the resulting voltage division was calculated. The results in the green box are really close to 3 db per octave especially when you remember that standard values are used:
https://wb9kzy.blogspot.com/2023/12/pink-noise-filter.html
Pete, N6QW, sometimes uses the term: noodling on the Soldersmoke podcast when discussing the design of a circuit. As I understand it noodling involves improving a basic circuit through an iterative design change and simulation cycle. This is done prior to building the circuit. I found a video where the presenter "noodles" a white to pink noise filter using LTspice to analyze the results:
source: https://www.youtube.com/watch?v=WkxOJcZEWtU
I learned a lot, not least of which was using LTspice to display frequency response and do measurements automagically.
BTW, I also learned that Dennis Bohn, the author of the Popular Electronics pink noise generator article mentioned in the previous blog post, worked for National Semiconductor (the vendor of the MM5837). He was also the editor of the National Semiconductor Audio Handbook from 1977:
The Audio Handbook mentions the pink noise filter and a little about the design:
It also struck me after reading this National Semiconductor Audio Handbook entry on the pink noise filter that there was no reason (in the previous blog post about the pink noise filter) to do the db calculations above 20,000 Hz (the upper frequency limit of hearing). This makes that data look much better.
I also tried simulating the pink noise filter circuit in a spreadsheet (rather awkwardly I'll admit). At each of the octave related frequencies from 20-20,000 Hz the capacitive impedance was calculated and then the resulting voltage division was calculated. The results in the green box are really close to 3 db per octave especially when you remember that standard values are used:
I'm not sure why the LTspice results don't match, probably something to do with my setup.
I suspect that Dennis Bohn used plain old paper and pencil to design that filter and did a darn good job, too ! :)
Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm
Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm
