I don’t, and haven’t used one. I suspect it’s not worth getting into it for this project?
The solder paste has a finite shelf life, longer if refrigerated, and the tool is $60-$260 depending on how nice a hot air tool you want. So probably not. When you get deeper in you will hit the issue that almost every modern part is smd with no through hole equivalent. Also it’s really neat how you can smear paste on, and the paste thermodynamically wants to stick to metal and connect the part to the pads.
My current draft (as pictured here) does both, which is the KiCad default.
I remembered something. Normally in topology you want to be sure your analog ground, which seems to be piezo ground, is upstream of the digital ground.
Also you seem to be pulling from 3.3 v digital, you may or may not get audible digital interference. Normally you want analog power which comes from a more expensive and specialized power supply different from the supplies that power the digital parts. And topology your analog negative needs to return the that power supply first and then a trace goes to the digital side. This is to reduce noise, you also can do things like a separate internal power plane for each, or to bridge the ground planes at exactly one point between the side for the tiny and the side for the analog circuits. And you would put a bridging component between +5 or +12 and 3.3 that gives analog power linearly.
Audio science review forums will have domain experts who are much more knowledgeable than I am about this, it’s very hard to make “perfect” analog acoustic circuits where any design compromises are no longer audible. But it can be done.
When you get deeper in you will hit the issue that almost every modern part is smd with no through hole equivalent.
I’m not currently planning to get deeper into this, but we’ll see!
Audio science review forums will have domain experts who are much more knowledgeable than I am about this, it’s very hard to make “perfect” analog acoustic circuits where any design compromises are no longer audible. But it can be done.
One nice thing about this project is that I’m not trying to capture high-quality audio: I only need it to be good enough to work as a sensor.
Testing with a breadboard the 3.3v digital seems to be good enough, and the noise I’m getting seems to be RF on the piezo lines which is hard to avoid.
The solder paste has a finite shelf life, longer if refrigerated, and the tool is $60-$260 depending on how nice a hot air tool you want. So probably not. When you get deeper in you will hit the issue that almost every modern part is smd with no through hole equivalent. Also it’s really neat how you can smear paste on, and the paste thermodynamically wants to stick to metal and connect the part to the pads.
I remembered something. Normally in topology you want to be sure your analog ground, which seems to be piezo ground, is upstream of the digital ground.
Also you seem to be pulling from 3.3 v digital, you may or may not get audible digital interference. Normally you want analog power which comes from a more expensive and specialized power supply different from the supplies that power the digital parts. And topology your analog negative needs to return the that power supply first and then a trace goes to the digital side. This is to reduce noise, you also can do things like a separate internal power plane for each, or to bridge the ground planes at exactly one point between the side for the tiny and the side for the analog circuits. And you would put a bridging component between +5 or +12 and 3.3 that gives analog power linearly.
Example : https://www.analog.com/media/en/news-marketing-collateral/product-highlight/low_dropout_regulators.pdf. (May be massive overkill)
Audio science review forums will have domain experts who are much more knowledgeable than I am about this, it’s very hard to make “perfect” analog acoustic circuits where any design compromises are no longer audible. But it can be done.
I’m not currently planning to get deeper into this, but we’ll see!
One nice thing about this project is that I’m not trying to capture high-quality audio: I only need it to be good enough to work as a sensor.
Testing with a breadboard the 3.3v digital seems to be good enough, and the noise I’m getting seems to be RF on the piezo lines which is hard to avoid.