This chapter is from the book
This chapter is from the book
This chapter is from the book
Relevant Technician Tools
To perform all aspects of physical computing with your Raspberry Pi, you’ll need a few electrical tools. Chief among these is the digital multimeter, an instrument with which you can measure electrical current, voltage, and resistance.
For instance, you can run a quick verification of the Raspberry Pi’s 5V power supply voltage by using a multimeter and the TP1 and TP2 test points on the Model B board.
To locate the TP1 and TP2 test points, take a closer look at Figure 2.2. You’ll see TP1 located just above and to the right of the C2 capacitor and TP2 just to the left of the RCA video output (assuming you are looking at the PCB with the Raspberry Pi logo facing up).
Task: Check Raspberry Pi Voltage with a Multimeter
- Turn on your multimeter and set the dial to a low voltage threshold (for instance, 20V is good). If you own an autoranging multimeter, you don’t need to worry about this step.
- Disconnect all peripherals (including the SD card) from your Pi except for the Micro USB power supply cable.
- Power up your Pi.
- Place the hot (red) lead to the TP1 test point, and place the ground (black) lead to the TP2 test point. You want to connect the leads simultaneously.
Verify that the multimeter shows a net voltage of approximately 5V (see Figure 3.7).
FIGURE 3.7 You can use a multimeter and two PCB test points to quickly verify Raspberry Pi voltage.
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You’ll also need a soldering iron, which is a tool you use to permanently join electrical components and to extend circuits.
The very idea of soldering intimidates some people, but the kernel idea at play is really quite simple. You heat up the soldering iron to 700 degrees Fahrenheit or so and then melt solder into a junction between two other conductive components. When the solder dries, you have a permanent connection that allows electrical current to flow between the soldered components.
In a nutshell, solder is a fusible metal alloy that, as a conductor, can transmit electricity.
For Raspberry Pi projects, I recommend you get an adjustable 30W pen-style soldering iron for maximum flexibility. You also should purchase a spool of 60/40 lead rosin-core solder with a 0.031-inch diameter. The 60/40 means that the solder consists of 60 percent tin and 40 percent lead.
To make your soldering experience as user-friendly as possible, you might also want to look into the following relevant soldering accessories:
- Solder sucker: This vacuum tool makes short work of removing melted solder particles.
- Solder wick: This material, also called desoldering braid, is used in conjunction with the solder sucker to remove solder from your components.
- Soldering stand: We have only two hands, and if you are operating the iron with one hand and the solder wire with the other, then how the heck can you position your components to be soldered? Because using The Force isn’t an option (probably), a soldering stand makes this easy.