An electronics “breadboard” is actually referring to a solderless electronic board. It is a great unit for making temporary circuits and prototyping, and it requires absolutely no soldering.
Once you find an electronic project and the parts needed to build it, you will need to connect all the components according to a relevant circuit diagram. Creating the completed circuit is done usually by soldering the components on a printed circuit board (PCB). This approach is appropriate for circuits that have been tested and are functioning as desired, and also when the circuit is being made permanent. However, making a PCB design for just a few applications - for instance, while still developing the circuit - is not economical. Instead, while the circuit is under development and the parts count is low and there are no extremely high frequencies in use, the components are usually assembled on a solderless breadboard.
Breadboard Internal Connections
There are various types and sizes of breadboards, suitable for circuits of different complexities. Small sized breadboards can be used for prototyping small circuits and bigger boards are available for circuits having many parts (see photo 1). Breadboards can also be stacked together to make larger boards for very complex circuits.
The nice thing with breadboard design is that a circuit can be built and modified easily and quickly, and ideas can be tested without having to solder the components. Once a circuit has been tested and is working satisfactorily, the components can be easily removed and the breadboard can be reused for other projects. Reuse property, is the main reason of solderless breadboards being extremely popular with students and in technological education. There are also other prototyping boards, such us stripboards (veroboards) and prototyping printed circuit boards used to build semi-permanent soldered prototypes or one-offs, but these boards cannot easily be reused.
A typical breadboard (see photo 2) consists of rows and columns of holes spaced so that integrated circuits and other components can be fitted inside them. The holes have spring actions so the components leads are held tightly in place. Although solderless breadboards are available from several different manufacturers, most of them share a similar layout. The typical layout is made up from metal strips, used to connect terminals on a row or column. These metal strips run underneath the board and connect the holes on the top of the board. They can be easily revealed by removing the back cover of a breadboard (photo 2).
Figure 1 shows a typical internal connection layout of a breadboard. In the middle of the breadboard there is a small gap (a notch running in parallel to the long side) which separates the board into two halves. The gap is useful for placing typical DIP (Dual in-line Package) integrated circuits on it. The integrated circuits are placed such that the IC terminals of one side are on the left half of the breadboard, and the IC terminals of the other side are on the right half (see photo 3). When a DIP integrated circuit (such as a typical DIP-14 or DIP-16, which have 7.6 mm separation between the pin rows) is plugged into a breadboard, the pins of one side of the chip are supposed to go into column E while the pins of the other side go into column F on the other side of the gap.
The clips on the right and left of the gap are each connected in a radial way, and form the Terminal strips; typically five clips (i.e., beneath five holes) in a row on each side of the gap are electrically connected. The five clip columns on the left of the notch are often marked as A, B, C, D, and E, and they are connected to each other to a row basis while the ones on the right are marked F, G, H, I and J, and are likewise connected to each other in a row basis too.
There are also two pairs of columns at the left and the right side of the solderless breadboard of figure 1, and these columns are marked by coloured lines. They form the Bus strips and are reserved for the power and ground connections. The holes in each of these specific columns are connected to each other across their column line.
In most commercial available breadboards, any column intended for a supply voltage is marked in red, while any column for ground is marked in blue or black. Some manufacturers connect all terminals in a column in a single bus strip while others just connect groups of them in the same column. Because of the different configurations, the best way to check the absence or presence of continuity in a group of power terminals is by using a multimeter. On large breadboards, besides bus strips found either on left or/and right, additional bus strips can often be found on the top and bottom of terminal strips.
It is important to be aware that the power strips on different sides of the board are not connected, so for connecting the same power source on different sides, some jumper wires must be used. Additionally, colour lines markers or any other markers on power strips are there just for reference. Actually, there is no rule for plugging power into the "red" strip and ground into the "blue" one. However, it’s a good practice to keep everything in order.
The numbers and letters marked on various rows and columns of the breadboard are just for serving as a coordination system, for easily referring to a certain connection point of the circuit. These are also helpful when using instruction booklets found on many books and guides on building electronic circuits.
Jumper wires
Photo 3 shows a breadboard holding an integrated circuit and a number of resistors and capacitors. Some circuit connections are simply made by the Terminal and Bus strips. A component which is placed on a specific row or in a specific column-group is indeed electrically connected to anything else placed in the same row or column. However, for connections between different rows or different columns-strips, some wires are used.
These wires are called jumper wires (also called jump wires or wire bridges) and can be custom made from 22 AWG (0.33 mm2 or about 0,6mm in diameter) solid copper, tin-plated plastic-coated wire. Other wire gauges are not suitable because thicker ones do not fit at all and thinners may crumple when pushed into a hole and may damage the board when break off.
Jumper wires can be also obtained in commercial available ready-to-use packs. Ready-to-use jumper wires come in different colours, lengths and qualities. Some even come with tiny plugs attached to the wire ends. The number of available colors is somehow limited. Black and red wires are usually reserved for the supply voltages and the rest are simply used where convenient.
It is essential for custom made jumper wires, to be striped about 5 to 7.5 mm of insulation. With very short wires this can be quite a challenge. Shorter stripped wires might result in bad contact with the board's spring clips (insulation being caught in the springs). Longer stripped wires increase the likelihood of short-circuits on the board.
Another tip that will save you a lot of messing around is that the perfect wire for solderless breadboards can be found by cutting up some CAT-5 or CAT-6 network cables as shown in photo 4. It is a good idea to cut up many various lengths of breadboarding wire from some network cables ahead of time so you can concentrate on designing your circuit rather on searching for jumper wires.
Binding Posts
Some breadboards have binding posts that allow you to connect external power sources. In a brand new solderless breadboard those binding posts are not pre-connected. Connecting them is up to the user, and can be accomplished by using some jumper wires. The only reason for new breadboards having not connected their binding posts in any bus or terminal is for being totally customizable and not limited to predefined connections.
Typically, new breadboards come with 2 or 3 coloured binding posts; Black and red are usually for ground and main DC power supply, respectively. The third post comes usually in blue or yellow and it may be used for providing additional power supply or for any other purpose.
Photo 5. A typical breadboard which has binding posts
Breadboarding Tips
With a handful of semiconductors, a breadboard and some wires, you should be able to create just about anything you like. Don’t give up every time some smoke pours out of a transistor, or when a circuit does something completely unexpected, it’s all part of the game. Learn as you go, using the Internet, reference books, and other people’s designs as a guide and, before long, you will be able to whip up any type of circuit without any reference material at all. Just remember that any circuit you’re building on a solderless breadboard doesn’t necessarily have to look similar to the schematic. As long as all the electrical connections are being made, you can build your circuit any way you’d like! Below are some tips for helping you to use a solderless breadboard as efficient as possibly.
- It is important to make any circuit on breadboard in an convenient and systematic way, so that anyone can debug it and get it running easily and quickly. It also helps when someone else needs to understand and inspect the circuit.
- The standard way for connecting power supply is by using the side-lines (bus strips).
- Using black wires for ground connections (0V), and red for main power connections helps for easy inspecting during prototyping.
- Keeping the jumper wires close to the board surface and not curling them, also helps.
- Routing jumper wires around the chips and not over the chips helps quite a lot for easily changing the chips when needed.
- Trimming appropriately component terminals, so that they fit well and using as short jumper cables as possible is also essential for avoiding accidentally disturb a connection or pull out any component.
Breadboard limitations
Solderless breadboards are limited to operation at relatively low frequencies. This is due to the relatively large stray capacitance, being between adjacent metallic strips, and due to the relatively high inductance of the srips and jumper wires.
Connections on a solderless breadboard have relatively high contact resistance (compared to a properly laid out PCB) which isn’t reproducible (differs in every connection). This becomes a problem mostly on frequencies above 10MHz but in some cases, depending on the nature of the circuit, can already be a problem for DC and very low frequencies.
Breadboards can not be used in high voltage or high power circuits due to their limited voltage and current ratings.
Solderless breadboards usually cannot accommodate surface-mount technology devices (SMD), components with multiple rows of connectors not matching the DIP layout, and generally all components with grid spacing other than 0.1 in (2.54 mm). In many cases, those components can be connected to the breadboard by using small PCB adapters called "breakout adapters". Such adapters carry one or more components and have 0.1 in (2.54 mm) spaced male connector pins in a single in-line or dual in-line layout, for insertion into the solderless breadboard. Not matching components are usually plugged into a socket on the adapter, while smaller components (e.g., SMD resistors) are usually soldered directly onto the adapter, and the adapter is then plugged into the breadboard via the 0.1 in (2.54 mm) connectors. However, the need to solder the components onto the adapter negates some of the advantage of using a solderless breadboard.
Solderless breadboards are mostly made to be used at relatively simple circuits, and become unreliable when used on complex circuits. This is due to their convenience of easy plugging and unplugging of connections which makes also it too easy to accidentally disturb a connection.