Jumper Wires and Circuit Wire

Two different kinds of wire go into this car, and using the wrong one is the difference between a connection that survives being driven into a skirting board and one that does not.

Male-to-female jumper wires

These are the rainbow ribbon. They connect the modules to the Arduino, and the reason they are male-to-female and not either of the other two kinds is simply what is on each end:

• The Arduino's headers are sockets, so the Arduino end of the wire has to be a pin — the male end.
• The HC-06 and the L298N present pins, so that end of the wire has to be a socket — the female end.

Count what the car needs before you buy: six for the L298N logic pins (EnA, EnB and IN1 to IN4), four for the HC-06, three for the buzzer module, plus the two power leads. A standard 40-way ribbon covers it several times over, and you will pull the spares apart for the next project anyway.

Colour discipline saves you an evening

The ribbon comes as a rainbow because it is meant to be split up, not kept as a block. Two rules are enough:

• Red is always +, black is always ground. Never use them for anything else, on any part of the car.
• Keep one colour per module. If the HC-06's TX is green today it should be green when you rewire the car in a month.

The failure these actually cause

Push every connector fully home — you should feel it click over the shoulder of the pin, not just perch on the tip. Then, once the car works, put a small dab of hot glue where the wires meet the HC-06 and the L298N headers. It peels off with a fingernail when you want to change something, and it ends the problem.

Connections without soldering

Circuit wire, for the screw terminals

The L298N's motor and power connections are screw terminals, and a jumper wire's crimped end does not belong in one. Use plain solid-core wire, around 22 AWG — that carries the car's couple of amps with room to spare.

• Strip about 5 mm, no more. Bare copper sticking out past the terminal is a short waiting for a knock.
• Solid core, not stranded. Stranded wire frays as the screw turns and one stray strand reaches across to the next terminal.
• Tighten firmly, then tug the wire. If it moves, it was not tight.
• Red and black here too, for the battery leads.

Every part of the car