Using the Breadboard (Socket Board)

Using the Breadboard (Socket Board) The bread board has many strips of metal (copper usually) which run underneath theboard. The metal strips are laid out as shown below. These strips connect the holes on the top of the board. This makes it easy to connect components together to build circuits. To use the bread board, the legs of components are placed in the holes (the sockets). The holes are made so that they will hold the component in place. Each hole is connected to one of the metal strips running underneath the board. Each wire forms a node. A node is a point in a circuit where two components are connected. Connections between different components are formed by putting their legs in a common node. On the bread board, a node is the row of holes that are connected by the strip of metal underneath. The long top and bottom row of holes are usually used for power supply The rest of the circuit is built by placing components and connecting them together with jumper wires. Then when a path is formed by wires and components from the positive supply node to the negative supply node, we can turn on the power and current flows through the path and the circuit comes alive. For chips with many legs (ICs), place them in the middle of the board so that half of the legs are on one side of the middle line and half are on the other side. A completed circuit might look like the following. Both are 4 bit D/A circuits Notes: Depending on the size of the breadboard, there might be a break in the connection in the middle of the board for the ground and voltage connections. Ohm out the board from point to point to verify you have a continuous connection. All components should be same gage wire, otherwise you will get intermittent connections. The standard wire size is 22 gage. You should have at least three different colors. Black for ground, Red for voltage and a third color for signal interconnects. Notice that the tie points come in groups of 5. These 5 points are electrically connected to each other, allowing you to connect one wire to four others. There are also distribution strips which are usually used for distributing power (usually +5V for TTL circuits) and ground around the breadboard, since the circuit will likely connect to these in several places. On the breadboard shown above, these distribution strips come in pairs of 5 sets of 5 tie points. The electrical connections of these tie points are indicated by the lines next to them. A common use of the distribution strips is to have +5V on one of the pairs and ground on the other. Dual inline integrated circuits (IC's) such as digital logic chips and op amps are inserted into the board by straddling two rows of tie points. (Make sure you don't order surface mount elements if you want to use them on the breadboard!) Some tips to making a clean, easy-to-debug breadboard: • Use the distribution strips. • Use black wire exclusively for ground and red wire for power (often +5V). • Take time to cut the wires to length so that they can lie flat on the breadboard. • Run wires at 90 degree angles (vertically and horizontally); avoid diagonals. • After stripping the insulation, bend the exposed part of the wire 90 degrees using your fingers or a pair of needlenose pliers. Do this before inserting into the board. This makes it easier to make the wire lie flat. • When stripping the insulation from a very short wire, use needlenose pliers to hold the wire firmly while stripping. • Hold the wire with needlenose pliers to help you insert it or pull it out. • Be sure to remove IC's using an IC extractor (chip puller), not your hands, to avoid bending the pins. • If you are running wires onto the breadboard from external sources, connect them all in a single area distant from the main circuit on the breadboard, so you don't have wires running off the breadboard from many different locations. You might also consider buying an assortment of different lengths of prestripped and prebent 22 gauge wire jumpers. Jumper wires — which are used to connect components in a breadboard — save you a lot of time you might otherwise spend cutting small wires to length, stripping them, and bending the stripped wire when you're building a breadboard. Notice that the tie points come in groups of 5. These 5 points are electrically connected to each other, allowing you to connect one wire to four others. There are also distribution strips which are usually used for distributing power (usually +5V for TTL circuits) and ground around the breadboard, since the circuit will likely connect to these in several places. On the breadboard shown above, these distribution strips come in pairs of 5 sets of 5 tie points. The electrical connections of these tie points are indicated by the lines next to them. A common use of the distribution strips is to have +5V on one of the pairs and ground on the other. Dual inline integrated circuits (IC's) such as digital logic chips and op amps are inserted into the board by straddling two rows of tie points. (Make sure you don't order surface mount elements if you want to use them on the breadboard!) Some tips to making a clean, easy-to-debug breadboard: • Use the distribution strips. • Use black wire exclusively for ground and red wire for power (often +5V). • Take time to cut the wires to length so that they can lie flat on the breadboard. • Run wires at 90 degree angles (vertically and horizontally); avoid diagonals. • After stripping the insulation, bend the exposed part of the wire 90 degrees using your fingers or a pair of needlenose pliers. Do this before inserting into the board. This makes it easier to make the wire lie flat. • When stripping the insulation from a very short wire, use needlenose pliers to hold the wire firmly while stripping. • Hold the wire with needlenose pliers to help you insert it or pull it out. • Be sure to remove IC's using an IC extractor (chip puller), not your hands, to avoid bending the pins. • If you are running wires onto the breadboard from external sources, connect them all in a single area distant from the main circuit on the breadboard, so you don't have wires running off the breadboard from many different locations. Using a Prototyping Breadboard Using a Prototyping Breadboard A prototyping breadboard allows you to quickly build and test a circuit before constructing it more permanently on either a printed circuit board or on perf board using solder or wire wrap. Here is a picture of a typical breadboard: file:///C|/Documents%20and%20Settings/user/Desktop/tech%20folder%20labs/breadboard.html (1 of 2)6/12/2008 5:04:19 PM Using a Prototyping Breadboard At the top are binding posts which allow you to hook up power to the breadboard tie points. Some breadboards have their own power supplies; others connect to an external power supply by means of banana plugs which plug into the binding posts. Tie points are connected by 22 AWG (22 wire gauge) solid hookup wire. Simply strip off about 1/4 inch of the insulation at each end of the wire and insert into the tie point. Don't use stranded wire. (For a final version of a circuit not on a breadboard, however, stranded wire is usually better since it is less likely to break under repeated bending.) Most breadboards can accept wire sizes in the range 19-29 AWG, but 22 AWG is standard. The lower the AWG, the thicker the wire, just like with pasta. Thicker wire should be used for higher current. Notice that the tie points come in groups of 5. These 5 points are electrically connected to each other, allowing you to connect one wire to four others. There are also distribution strips which are usually used for distributing power (usually +5V for TTL circuits) and ground around the breadboard, since the circuit will likely connect to these in several places. On the breadboard shown above, these distribution strips come in pairs of 5 sets of 5 tie points. The electrical connections of these tie points are indicated by the lines next to them. A common use of the distribution strips is to have +5V on one of the pairs and ground on the other. Dual inline integrated circuits (IC's) such as digital logic chips and op amps are inserted into the board by straddling two rows of tie points. (Make sure you don't order surface mount elements if you want to use them on the breadboard!) Some tips to making a clean, easy-to-debug breadboard: ● Use the distribution strips. ● Use black wire exclusively for ground and red wire for power (often +5V). ● Take time to cut the wires to length so that they can lie flat on the breadboard. ● Run wires at 90 degree angles (vertically and horizontally); avoid diagonals. ● After stripping the insulation, bend the exposed part of the wire 90 degrees using your fingers or a pair of needlenose pliers. Do this before inserting into the board. This makes it easier to make the wire lie flat. ● When stripping the insulation from a very short wire, use needlenose pliers to hold the wire firmly while stripping. ● Hold the wire with needlenose pliers to help you insert it or pull it out.

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