Explore how to use solderless breadboards to prototype and debug circuit designs. Learn how breadboards are laid out, how to connect different types of components, and how to power your circuits.
- Back in the early days of electronics, hobbyists and tinkerers would assemble their prototype circuits on wooden breadboards like this one, using wires and nails to attach components. I imagine there were quite a few unhappy parents and spouses who didn't like seeing their kitchen equipment used for that. so now we have specially-designed boards for prototyping circuits. But we still call them breadboards. Using a breadboard is the easiest way to build and test new circuits. They hold circuit components in place and enable you to connect them without soldering, which is a process for permanently attaching electrical components together.
Since breadboards don't use solder, that means the circuits are temporary, which makes breadboards great for building quick prototypes, because you can easily change the circuit if something goes wrong. Breadboards come in a variety of shapes and sizes, but they all work in the same way. You connect components to the breadboard by simply inserting their metal leads into holes. There are tiny little metal clamps inside of each hole, which hold the component in place and electrically connect it to certain other holes. I often use needle-nose pliers to insert component leads into the breadboard, especially in crowded circuits.
It makes things easier. Most breadboards have lines of holes that run along the length of the breadboard that are labeled with red and black plus and minus symbols. These holes are internally connected to each other lengthwise down the board, and they're used to distribute power to the circuit components, and are often referred to as the power bus. The red line is typically connected to the positive voltage of the circuit's power supply, and the black lines are connected to ground, or the negative supply of voltage. I would recommend using a breadboard power supply like this one, which is connected to a wall adapter, and then provides either 3.3 volts or five volts to the power bus on either side of the breadboard.
The holes in the middle section of the breadboard are used to hold and connect to the circuit components. These holes in the same row going across the board are connected to each other inside of the breadboard, but each individual row is separate and not connected to any of the other rows. The holes on the left and right side of the breadboard are also separated by a troth that runs down the middle of the breadboard, and they're not electrically connected to each other. To build a breadboard circuit based on a schematic, you simply work your way through the schematic to add and connect to the appropriate components.
For example, consider this simple circuit, which consists of three resisters connected to each other and a five-volt power supply. The first thing I need to do is connect my power supply to the power lines, and make sure it's configured for the correct voltage, in this case, five volts. Although the power supply is connected, it's currently turned off. You should always build circuits with the power off. There are two reasons for that, and both of those are related to safety. Applying power to partially-built circuits could cause current to flow through components in unexpected ways and cause damage to the circuit, and more importantly, turning the power off protects you from electrical shock, if you accidentally connect or touch the wrong components.
Now, I'll add the first resister to the circuit. Looking at the schematic, I see that one side of this resister is connected to the positive five-volt source, so I'll insert it into the positive power bus. The other side of the resister is connected to other components, so I'll choose a hole in a nearby row across from it and attach it there. Now for the second resister. One side of it is connected to the first resister, so I'll insert one of its leads into this same row of holes as the first resister. So now they're connected to each other.
The other side of this resister is connected to ground. I could connect it directly back to the ground line of the power bus, but now these two resisters are squished together, and it's going to be tough to fit the third resister into this arrangement. One of the biggest challenges when breadboarding circuits is figuring out where to place components. You should try to organize the components in a way that's easy to follow when looking at the schematic. That'll make things easier when you need to debug or swap out parts of the circuit later. You can use small pieces of wire called jumpers to connect components from different parts of the circuit.
Using prebuilt jumper wires like these are convenient for building and assembling small circuits because they have metal leads already attached to each end that easily fit into the breadboard holes. The one downside to using prebuilt jumper wires is that they come in standard lengths that can't change. As your circuits grow in size and complexity, you can quickly end up with a large mess of excess wire. For my own circuits, I prefer to use spare wire and a pair of wire strippers to create my own jumpers that are only as long as I need.
When creating jumper wires to use on a breadboard, you should always use solid-core wire, which has a single strand of metal inside. I recommend using 22 gauge wire, because it's just the right thickness to insert into breadboard holes. Avoid using stranded-core or braided-core wires, which contain a bunch of tiny conductor strands, because the strands tend to get squished or separated when you try to shove them into a breadboard. To create a jumper wire for my breadboard, I'll cut off a piece of wire that's about half an inch longer than I need it to be, then I'll find the notch on my wire strippers that corresponds to the thickness of the wire, and I'll use that notch to strip off about a quarter of an inch of plastic insulation from each end, being careful not to cut too deep and damage the metal core.
Finally, I use a pair of pliers to bend each end to a 90 degree angle. Using that jumper wire in my circuit allows me to connect the second resister to ground while keeping the layout of the components organized. Now to connect the last resister for this circuit, which should be connected in the same way as the second resister. I'll connect one end to the row of holes with the other resisters, and the other end goes into the row that I've already connected to ground with the jumper wire. Now that the circuit is built, I'll turn on the power.
This circuit doesn't do anything I can see, like turn on a light bulb, but I can check that it's working correctly with my multimeter by connecting that black probe to ground and then using the red probe to measure the voltage at different points throughout the circuit. If I detect that there's a problem, then I would turn off the power, make adjustments, and try again. One final thing I do to keep my breadboard neat and organized is trim down the length of a component leads to remove excess wire. Keeping the leads short keeps a circuit compact, and reduces the chance that metal leads of nearby components might accidentally touch each other and cause a short circuit.
- Reading electrical schematics
- Building circuits on breadboards
- Reviewing types of static and variable resistors
- Reading resistor color codes
- Measuring resistance with a DMM
- Measuring resistive sensors with an Arduino microcontroller
- Making electrical signal measurements with an oscilloscope
- Measuring AC voltage with a DMM
- Understanding the time domain and frequency domain
- Designing passive low-pass and high-pass filters
- Reviewing reactive RC and RL circuits
- The relationship between capacitors and inductors