Lighting an LED using a Breadboard & a Raspberry Pi

Lights, Jumpers & the Resistance –

Jumper wires are typically 22 gauge solid-core wires with insulation pre-stripped and readied for insertion in or out.

Resistors resist the flow of electrical current, thereby controlling WHERE and HOW FAST it flows. [Thought experiment: If controlling water, using thin pipes would let less water through but would flow through faster than a similar amount of water in a thicker pipe, albeit the latter would let a larger quantity of water through. If you had a fire hydrant, you want high resistance, i.e. highly pressurized water: if you have a water fountain, you might prefer less resistance, and less pressure. If you had the pressure from a fire hydrant in a water fountain, this would lead to a very unpleasant drinking experience, and water fountain-level pressure in a fire hydrant would lead to happier arsonists.]

Lighting an LED using a Breadboard & a Raspberry PiAn LED is a light emitting diode. A diode lets current flow only one way, from positive to negative. An LED has a quick distinguishing feature: the positive leg/ lead is visibly longer than the negative lead. If the leads are clipped, there are 2 other ways to tell: (1) the anode (in a device that consumes power, the anode is positive, but in a device that produces power, the anode is negative) or positive is going to be the bigger metal piece inside a transparent LED, or (2) test using a power source.

Resistance is measured in ohms, written Ω. The bigger the Ω, the greater the resistance. Measuring resistance can be done either by color-coordinated stripes on the resistor’s body (resistor color code), or more accurately using a multimeter. A resistor is the same from either pin/ end; there is no forward or backward direction.

Breaking out my breakout board –

The breakout board is an extended pin-out from the Pi, to the breadboard ( or any other device for that matter). It replicates the existing pin-out on the Pi, communicating through the ribbon cable.

A breadboard (pictured below) is a device used for prototyping circuits. It allows easy and fast access of components: as fast as you can pull out a thin wire from a slot. One of its advantages is that it does not need soldering, which makes most n00b errors, mulligans. A breadboard is basically a plastic brick/ block that has a lot of holes, typically spaced 0.1″ apart. Into these holes doth one plug in leads/ wires, that are then held in place by metal contacts. There are many columns, in my case, numbered long-side from 1 – 30, and short side from a – j: 30 holes by 10, for a total of 300. In addition, there are +ve and -ve holes on either side of these 300, each 2 holes by 5 per chunk, by 5 chunks per side, i.e. 50 per side and 100 total +/- holes. The +/- is the power and ground rail respectively.

Lighting an LED using a Breadboard & a Raspberry Pi DiagramIt is important to understand how these rows and columns work. If you put power into, say, the right side the whole row, i.e. from the red + straight down to the other red + only on that side. The same applies for the negative (ground), and the same applies for the other side. Within the body, the lettered/ numbered holes (not in the power rails), work the opposite way, i.e. in columns, and only on its side of the center ridge. Plugging a jumper wire into c-28 would communicate with a-28, b-28, d-28, and e-28. It wouldn’t communicate with f-28, because of the ridge’s separation. You don’t have to match power/ground, simply powering/ grounding one side effectively performs that action to all the holes on that side of the power rail. To reiterate, from a to a or – to – is a row, and from 25 to 25 is a column.


For more detail: Lighting an LED using a Breadboard & a Raspberry Pi

© 2015 Powered By Engineering Projects Team, Raspberry Pi Projects

Scroll to top