Breadboard Layout Tips

Breadboards are a good way to quickly start building up an electronic circuit and experimenting. A breadboard consists of rows of connected metallic springs contained in a plastic carrier with holes for component leads. This allows you to make connections between components easily.

The typical arrangement is in rows of 5 holes which are connected. The holes are spaced 0.1 inch apart, with gaps between the ends of each row. This is great for old style ICs with 0.1″ pin spacing, leaded transistors, resistors, and capacitors. Some components are more difficult to use with a breadboard for various reasons.

Here are a few tips on using some of the these components on a breadboard.

2-row headers:

dual header

These have two rows of headers and cannot directly be plugged into a breadboard because the two rows will short-out. The gap between rows in the breadboard is too wide for the two rows to be separately connected. Two ways to deal with this are to use jumper wires, or an adapter to widen the gap between the rows. If using jumper wires you can rearrange the wires that go into the breadboard in whatever way is convenient for you. These can then be taped up and formed into a row using a cable tie, so the component can be easily removed and put back into the circuit as needed.

Example of a module with a 2x4 pin header wired for connection to a breadboard

Example of a module with a 2×4 pin header wired for connection to a breadboard. Note cable ties used to keep it neat but are not necessary.

Devices with thick legs

A good example of this are TO-220 package devices, usually transistors or voltage regulators. The leads on these are slightly too wide for the breadboard. You can force them in but it makes the holes in the plastic wider, and holds the springs open quite wide. Sometimes you end up with rows on the breadboard that can only be used for these wide-pin devices and not for regular wires anymore, because the spring has stuck open. The solution here is to solder the device to a .1″ header, or plug it into jumper wires which are then plugged into the breadboard.

A large transistor soldered to a header to fit into the breadboard

A large transistor soldered to a header to fit into the breadboard

Surface-mount devices

These don’t have long enough leads to be plugged into a breadboard, and they have the wrong pin-pitch anyway. The solution is to use an adapter board or a break-out a board. A break-out board is a board specifically designed for the particular device and may have additional supporting components. An adapter board is generic – it simply brings out all the leads of the surface-mount device to .1″ headers to be used on the breadboard. It’s useful to be able to use surface-mount devices in a breadboard circuit because the device may not be available in a through-hole package, or you might prefer to use the exact same package that you will eventually put into a permanent circuit.

Multiple devices of the same type

For example, Resistors, LEDS, switches, transistors. If you need more than one or two of these, they are often available in an array or network package, or you can create your own re-usable circuits on a small PCB or prototype board. If you create your own, you can build them so that they sit between the power rails and regular rows on the breadboard.

Pre-built packages:

DIY LED circuits for use on breadboard:

Long-leaded components

Resistors, capacitors, transistors, diodes, LEDS can all come with quite long leads. Once you figure out where they will go in your circuit the leads can be cut to length, so that the component rests directly on the breadboard instead up sitting up on the air. This makes the component less likely to pop out and prevents wires from touching when they shouldn’t.

Resistors on breadboard with trimmed leads

Resistors on breadboard with trimmed leads

Short-leaded components

Sometimes a component’s lead breaks, or you are using a component salvaged from another circuit and the leads are too short to make contact with the connector inside the breadboard. In this case ,it’s best to solder some extra wire to the component before placing it in the breadboard.

Components with awkward pin-outs

Sometimes you can reduce the number or length of wires you have to use to connect components by orienting the components differently, swapping their positions, or using an alternative component that has a more convenient pinout. An example of this is the 74HC373 and 74HC573. These are both 8 channel latch ICs with the same logical configuration, but the 373 has its inputs and outputs interleaved, and the 573 has inputs on the left, outputs on the right. This makes the 573 much easier to wire up on a breadboard. If you are using a microcontroller, think about the GPIO pin arrrangement, maybe it’s possible to change the pin assignment to better suit the physical arrangement of the circuit.

Heavy components

These are liable to fall out of the circuit when it is moved. They can be attached more securely by wrapping a cable tie around the component and the breadboard, or by mounting the component off the breadboard and connecting using leads.

Motor cable-tied to breadboard. Not a permanent solution but enough to stop it moving around while I test my circuit.

Motor cable-tied to breadboard. Not a permanent solution but enough to stop it moving around while I test my circuit.

Previously soldered components

These can have blobs of solder on them, its best to cut the lead shorter if possible, or use a soldering iron to smooth out any bumps. If they are plugged into the breadboard with bumps on the leads,  it can damage the springs inside the breadboard or make the component difficult to remove.

Board layout

Some breadboards come attached to a base. Others come with double sided tape to attach to a base. If you use a base for the breadboard, it’s easier to keep everything together. Large and heavy components and breakout boards can be attached to the same base as the breadboard and connected using leads.

LCD and binding posts on breadboard base

LCD and binding posts on breadboard base

Wiring – long, flexible wires with a formed end for plugging into a breadboard are commonly available. These are useful when building up and testing a circuit initially because they are easy to plug in and remove, but the wiring quickly becomes messy. It’s good to switch these for thicker wires as short as possible that can be bent into shape. If you have multiple connections to one point on the board, the connections can be daisy-chained rather than going back to one point. A good example of this is if you have two connections to ground right next to each other – just join them together with a short wire.

As well as the common two-column + power boards, where ICs have to be stacked end to end, you can also get multi-column boards. This way, ICs can be stacked side by side and it makes connections easier.

Horizontal and vertical breadboards

Horizontal and vertical breadboards

If the springs in your breadboard do wear out or get damaged, you can replace them by buying a cheap, small board, and taking out a row of springs. Rows of holes 5 long are very common and seem to be the same between boards. To get at the springs, you have to remove the breadboard from its base, then peel back and plastic or tape backing. The spring can then be pushed out by pushing a pin in the top of the holes corresponding to the spring until it starts to come out the bottom, it can then be levered out using a small screwdriver

underneath breadboard 1

The underside of a breadboard – metal springs

 

Replacement springs from a tiny breadboard

Replacement springs from a tiny breadboard

Author: Paul

Share This Post On

1 Comment

  1. Excellent practical advice.

    Post a Reply

Leave a comment