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ChelseaBack

January 27, 2015 17:54

Getting to know DesignSpark PCB

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First time ever using design software for schematic capture and PCB layout.

One of my favourite projects to date was when I made a light theremin on perfboard. While the project was fun and the finished product looked great fitted inside a die-cast case, the circuit inside really did look like a prototype. So I decided to revisit the same project but with a slight change: this time using the free to download software, DesignSpark PCB, to create my own custom PCB which will be sent off to manufacture.

Having not used PCB design software before I had a lot to learn, and fortunately I found loads of great tutorials on DesignSpark which got me off to a good start.

Schematic entry

The first thing I started with was schematic entry. I found the easiest way to do this was by having a rough hand drawn schematic and BOM with RS part numbers. I could then use the quick search bar in ModelSource (a component library built into the design tool) to find parts, before dragging and dropping them onto the schematic and creating connections between them.

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One issue I did encounter was when there was not a suitable footprint available in ModelSource. I found help with this again through looking at forum posts and watching tutorials, and it became clear that the simplest solution is to copy an existing component and modify this. By doing so you can change the footprint to the required specifications and also change the package so that it matches part in the BOM. This is a great way to build custom parts which can then be used in future designs.

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I had a couple of components which weren’t showing in the ModelSource library, an example of this was the type of battery terminal I required. This was simple to resolve as I opened up a new window and found a battery clip in ModelSource, I was then able to use this footprint in my schematic and edit it so that it fitted my requirements.

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Board Layout

Upon finishing schematic entry I reviewed the design several times before translating it to a board layout. Once translated the components can then be arranged either inside or outside of the board (the dimensions are specified as part of this). I found it easier to arrange the components outside of the board, because you have more space.

After the components were placed the nets (connections between components) needed to be routed. This can be done through auto-route or manually, but either way when complete I find it is always best to check the nets against the original connections in the schematic.

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If using auto route (like I did) some of the nets may need tidying up. After all the nets are placed and tidied I like to mitre the corners and re-position the vias (the route that tracks take from the top layer to the bottom layer of the board) to ensure there is enough space around them.

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Manufacturing

After checking the design meticulously, I then followed the design submission guidelines stipulated by OSH Park (my chosen manufacturer) for uploading.

On my first attempt at uploading I experienced an issue: I received an error saying that I didn’t have a board outline. I e-mailed the support staff at OSH Park and with their help managed to resolve the issue, which was done by generating a board outline on a new layer and naming the Gerber file appropriately.

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It was pretty daunting to start with, having never designed a printed circuit board before, but now I feel I have learned a lot, the overall experience is really satisfying and I can't wait for my board to arrive! 

ChelseaBack

Trainee Electronics Engineer for AB Open. Love to try new things and build interesting projects!