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Getting Started with Sid - Schematics

June 29, 2021

Getting Started with Sid - Schematics

Hey folks, Sid here again. This week I wanted to look at schematics. As we delve into larger projects with more components and potentially less instructions, schematics become more important. If you’re like me, schematics haven’t played a huge role in your life since 9th grade science class. Which means that when I look at them my brain kind of short circuits and then I look for a picture of the final set up so I can just copy that instead of trying to figure out the schematic. This also means that I have trouble coming up with the projects myself because I can’t plan them out properly. So let’s figure out reading schematics together so that maybe we can all look at them and know exactly what they are saying. 

Okay so starting from scratch. Schematics tell us what we are making. They show us a simple representation of the elements of a system using symbols instead of realistic pictures. Generally a schematic is not considered with the physical layout of the elements, whereas pictorial diagrams will show exactly where the components will lie. 

We’re going to focus more on a schematic diagram because that’s the one I get more confused looking at. 

First things first: this is what the components look like as symbols. I decided to print this off and keep it in my workspace so I can refer back to it with ease. I would recommend doing the same, it just cuts down on time when you have a cheat sheet next to you. 

It can also be helpful to pair the schematic symbol with the pictorial version so you can look through your components quickly and find what you need. 

So looking at these symbols is good but it’s also pretty important to figure out how they all go together on the schematic. When creating or reading a schematic you’re looking at how to make the power source connect to all the elements to make a complete circuit. 

There are two circuits you want to avoid: a short circuit and an open circuit.

Short circuits happen when you connect a wire from the positive side to the negative side of a power supply. This is dangerous. You should not do this. It can cause things to heat up too fast and start fires. A circuit needs something to slow the electrical current to prevent your power supply from trying to create an infinite current flow. 

An open circuit is a circuit that isn’t fully connected so there’s a gap in the flow of current. When this happens nothing bad will occur, no fires but there won’t be any magical moment of your project working. 

What you want to happen is a complete circuit.

This is a simple circuit schematic that shows a battery as the power source for a light bulb and has a switch. At its base this is what every single light bulb circuit in your house looks like. It gets more complicated the more light bulbs, switches and other electrical there are in the room which would lead to the schematic showing more bulb and switch symbols. 

Keeping this in mind it gets easier to build on a schematic. Generally when I’m getting overwhelmed and confused by a schematic I look at this one and then revisit the more complicated one. Find the power source and then follow the lines to each symbol, identify what the symbol is and go from there. I like to draw them out again and label the symbols just like I did on the 9th grade science tests just to simplify what it all means. 

Hopefully this helps clear up some schematic fears and bring a bit more confidence in reading them. Remember to go slow and be careful, if you get stuck take a step back and refresh your memory on the symbols and how it all connects.