Hey, I wanted to share couple of more information regarding my project. I am posting this post the deadline FYI.
Fixing the Boost Converter Noise
In my Part 4 - Post I mentioned that i made a mistake while laying out the PCB and i did not go as per the TI's Recommended Guidelines due to which the following issues happened
- The Power supply was noisy with a Vpp of 320mV
- There was a audible hum, an irritating one emanating from the circuit
So in my Final PCB i corrected it
Here is the before
This is the after
You should be able to note
- Only Ground has planes both on Top and bottom stitched by Vias. And it is PWR GND Net not The regular GND
- I did add a Low ESR Electrolytic capacitor
- No Pours under inductor and switching element
- PWR GND, AGND (For feedback Resistors) and GND are joined at a single Star Point. Star point is a single point where the PGND and GND is connected. It is achieved using NET Tie symbol in KiCAD. This reduces the noise in the main circuit and internet says it keeps the return path of the switching element isolated in the PGND net itself. The Pout of PGND and GND are not joined anywhere. They are two different Nets. (Look around the rectangular silk screen)
The ripples came down to 105mV measured as Vpp (Peak to Peak) without the electrolytic capacitor and 60mV measured as Vpp (Peak to Peak) with the electrolytic capacitor of 680uF. and The audible hum was gone
Improving the Light Throughput
The LED Is projecting the light on to a white surface which i use as a diffuser, but then some percentage of light reflects off the walls of it and makes it back to the PCB where it gets partially absorbed. So i added some reflective coating. That improved the uniformity of the light even more, Sadly it is only visible for the naked eye and my phone is not able to capture the difference
Sounds Recording
I started recording sound events for Edge impulse Training. I am collecting Washing machine, Pressure Cooker, microwave, fire alarm, door knock, door bell and baby crying. I put it in a share drive and asking Friends and Family to contribute. My Target is 50 per sound. if anyone is interested in contributing do DM me.
Do Comment, I hope i have not made my posts boring.
