This project ultimately just uses the power of the BBC Microbit to communicate via radio and control the LED strips, therefore this board started out purely as a passive breakout board to mount the MicroBit and connect it to the LED strip but quickly became more complex.
As I said in the previous post, I want my filters to perform in the same way as the MSGEQ7. The frequency response of this chip is given in it’s datasheet.
From the datasheet I can see that, to replicate this response, I will need 7 bandpass filters at 63Hz, 160Hz, 400Hz, 1kHz, 2.5kHz, 6.25kHz and 16kHz. Each filter will need a quality factor of 6 (this basically sets the bandwidth of the filter).
It’s getting harder and harder to find spare time to work on projects. Firstly, the holidays at MIT are tiny compared to the holidays I get at Cambridge, and now that it’s finally Summer I am doing an internship which keeps me pretty busy 5 days a week, and I still want time to explore California and surrounding areas.
Anyway, I want to do a project that looks good and has some analogue electronics in it. I will build a system that listens to sound via a microphone, breaks the sound down into frequency bands and displays how loud each frequency band is using a strip of LEDs. It’s a similar idea to a Colour Organ but I want 7 frequency bands and 10 volume levels per frequency band (a total of 70 LEDs).
Taking on board what I learnt yesterday, I repeated the procedure of making the PCB. This time the PCB came out better than before, with no bad connections 🙂
Soldering went well at first; all LEDs, resistors and switches went on with little problem and all work as expected. The trouble came when I was soldering the jumpers. I wish I had thought this through a little bit more before-hand and used through-the-hole, but nonetheless it is now working. I used Sellotape and printer paper to insulate the underlying tracks and then soldered the jumpers. After a number of worrying failures and a little bit of lost copper track (fixed with solder), it was done.
The only concern I have now is that when I solder the bluetooth module to the pads on the right-hand end, the jumper will unsolder and/or break. Fingers crossed.