In this exploration we are going to take your Alligator Clip Circuit as a starting point and move it onto a breadboard.
Before you Begin
Before you start his build you should have completed the Alligator Clip Circuit — and all associated Building Blocks. You should also review the Breadboard Building Block.
Breadboard Logic
Let’s quickly review the inner workings of breadboards (complete the Breadboard Building Block if you need more details). The surface of the breadboard is covered in small holes called tie points. These holes accept wires and component legs allowing quick, temporary and stable connections among parts.
It is vital that you memorize the internal pattern of connections of your breadboards.
Power Rails ( Busses )
Power rails run full width, top and bottom. They are labelled with blue and red silk screen. These labels indicate power connections. By convention RED rails get connected to the POSITIVE side of your battery pack or power supply and blue rails receive GROUND connections.
The Great Divide
I like to call the gap in the middle of the board the great divide. It is spaced so that integrated circuits (chips) can be easily fit onto the breadboard. the tie points above and below the great divide are associated with numerous terminal strips.
Terminal Strips (Middle)
The array of tie points in the middle of your breadboard cover rows of terminal strips. The terminal strips are arranged side by side. They do not cross the great divide and they do not connect directly to power rails.
Circuit Representations
During this course I will share circuit representations in several formats.
Schematics
The most reliable of these is the schematic. This representation gives a topological (relational) map of the components in a circuit and how they should be connected. Schematics do NOT described the physical orientation of parts, what sort of wire or conductive material to use, how much of that wire to use, nor where on a breadboard to place your parts. Schematics only describe electrical connections.
Diagrams and Photos
I also use photos and diagrams (the later usually made with software called fritzing). These hold the same basic information as a schematic but also define a specific instantiation of the circuit. These will show specific placement of parts and real world orientations.
Lets Build
We are now ready to start building our first circuit :: breadboard edition. This circuit is the hello world of electronics. It is a proof of concept circuit as well as a placeholder circuit — as we will learn later in term.
Our first circuit is a simple LED with current limiting resistor.
Goal of this build.
Remember, circuits are circles of conductors. The goal of this build is to get your LED glowing on a breadboard.
Parts you will need
- battery holder — loaded with AA batteries.
- wire battery clip
- LED-single color ( red OR green OR blue )
- fixed resistor (1k — what color bands is that?)
- resistor chart or worksheet
- a breadboard
Video :: First Circuit Breadboard Edition
Get the slides
Is it Glowing ? Celebrate!
Take a moment to celebrate if you got to this point and your LED is glowing. This may be a happy candy moment — your call. It is a simple circuit but it has a ginormous learning curve. Bask in the light of your little LED and know that it is just the start of big things to come.
Troubleshoot — mine didn’t glow 🙁 — Yet.
If your LED is not yet glowing don’t despair. Most circuits don’t work on the first try. Here are some things to try to test and troubleshoot your circuit.
- Disconnect your battery
- Is the battery hot ?
- feel it and make sure its cool. If its HOT you have a short circuit — a direct path from battery positive (battery clip red wire) to battery ground (clip black wire). FIND the SHORT solve it before you continue. This is not always obvious — and shorts can be dangerous — if you can’t find the error and your battery keeps getting hot — disconnect and reach out for help (see below).
- Is the battery cool?
- assuming your battery is cool to touch, you likely just have a misplaced connection on the breadboard OR your LED is in the wrong way.
- FLIP the LED — remember LEDs have polarity, and act as gates. Current can only flow through them one way. IF that doesn’t solve it flip it back (make sure flat side, short leg faces ground).
- If LED is right, this is next big point of error — Check that the LED and resistor legs that are supposed to connect are in the same terminal strip. And that they are on the same side of the great divide. They should be side by side in one short row.
- check your battery pack did you put each battery in properly? Make sure each battery is alternating direction with the +ve on each battery aligned with +ve in the holder? Check the battery clip — is it securely connected and seated (did you hear it ‘snap’ on). Check the wire ends of your battery clip — are they frayed? Do they insert easily? Try the other clip in your kit.
- Still not Working?!
- Double check the whole circuit — Start at red wire on your battery clip, make sure it is connected to a red rail on your breadboard.
- Check that the long leg of the LED is in the RED rail and is seated well.
- Confirm that the short leg of the LED is securely placed in a tie point.
- Confirm that the first resistor leg is on the same terminal strip as the short LED leg. (Resistors do NOT have polarity so flipping it won’t change anything — but good idea).
- Confirm that the second resistor leg in securely connected to the ground rail on your breadboard.
- Confirm that the ground wire is connect to the same rail as the resistor leg.
- Really, still not working … ok, let’s change some parts.
- try a different LED there is a slim chance the one you have is broken.
- try a different breadboard — sometimes these just don’t hold wires right. If this fixes it — throw the first breadboard out.
- try your other battery holder — move all the batteries to the other holder try again. Keep the first one it may have just been improperly loaded.
- Still? #$%^@$%! I feel your frustration
- eat one of the candies in your kit (its time).
- reach out — ask a friend, hit discord, go to the virtual makerspace, email steve