Project: MicroLit – PCB V2


A couple of things went wrong on the first PCB. Firstly, the fab I used did not support V-grooves, which meant that instead of being able to mount the BBC MicroBit vertically by snapping off the top section of the PCB, it had to mount horizontally. Secondly, I needed to include level translation so that the MicroBit (which operates at 3.3V) could talk to the LEDs (which operate at 5V).

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Project: MicroLit – PCB V1

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.

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Project: Spectrum – Filter Design

Frequency Response

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.


The 7 frequency band responses of the MSGEQ7

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).

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Project: Spectrum – Beginning

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).

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Project: Smart Watch – Making PCB and Successful Soldering :)

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 jumpers are messy, but I couldn't be happier with the other passive components.

The jumpers are messy, but I couldn’t be happier with the other passive components.

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.

Yay, the LEDs work.

Yay, the LEDs work.