The breadboard

Five holes are one wire

Under the plastic, a breadboard is rows of metal clips. A clip grips whatever is pushed into any of the holes above it, and it joins every hole it sits under. On a full-size board the numbered columns hold two strips of five holes each, so a column is two wires, not one.

Two legs pushed into the same strip are connected. Two legs pushed into different strips are not, however close they are. That is the whole idea; the rest of this page is checking it.

Pick a hole

Notice what does not light: the holes in the next column along, and the five on the other side of the channel. A strip joins five holes and stops. The long rails at the edges work differently, because they run the length of the board: that is where the power goes.

A full-size breadboard has 830 holes in all: 630 in the numbered columns and 200 on the four rails. On some boards each long rail is one piece, and on others it is cut in the middle so that the two halves are separate. Do not assume which yours is. Put the meter on continuity, touch one probe to a rail hole near each end, and listen. A beep means the rail runs the whole way. If there is silence, bridge the middle with a jumper before you rely on either half.

What a circuit looks like on the board

A circuit is a loop: from the supply through each part in turn and back. On a breadboard that means each part must stand in two strips, and the next part must stand in one of the same strips. Where two parts meet, they share a strip.

Every wrong version above looks plausible. All four are dark, and none of them says why. When a circuit does nothing, the question is always the same: which strip is the current supposed to go through next, and is that really where the leg is? A jumper one column off is the most common, and it takes a meter to find because it looks right.

Which jumper wire

The kit has jumper wires with three kinds of end. A male end is a pin that pushes into a hole. A female end is a small socket that fits over a pin. A breadboard has holes and a module's header has pins, so you pick the wire by what is at each end.

Two breadboard holes need a male-to-male wire. A breadboard hole to a module's header pin needs male on the breadboard end and female on the module end. Two header pins, as when you link two modules directly, need female to female. If you find yourself pushing a female end into a hole, stop: it will go, but it will not grip, and the contact will drift.

Before you build

Seat parts straight down and leave the legs long enough to bend flat. Do not reuse one hole for two legs, because the clips are made for one. Keep the red jumpers on the + rail and the black on the − rail; the habit is worth more than the colour. And before you put any power on a new circuit, put the meter on continuity and touch the two ends of every joint you doubt. Ten seconds with the meter is cheaper than ten minutes of looking.