Connecting Your Equipment to the PedalPC
There are two types of electricity, alternating current (AC) and direct current (DC). AC is the type supplied to your home by your electric utility. It best suited for large loads like electric motors and heaters.
DC is the type stored in batteries. Most consumer electronics like laptops, monitors, and phone chargers run on DC, using a power adapter to convert household AC to the DC they need.
Anytime electricity is converted from AC to DC or vice-versa, some power is lost. For a large generator used by an electric utility, this loss are a tiny fraction of the total power generated. But for a small power generator like the PedalPC, it can add up to a significant fraction of its output.
Since most of the equipment you will be powering requires DC anyway, the PedalPC has DC power outlets instead of household AC power outlets. This prevents any unnecessary DC-to-AC and AC-to-DC power conversions, reducing power loss and allowing you to power more and larger electronic equipment.
Equally important to the type of electricity (AC or DC) a device requires is it’s input voltage and power jack dimensions. The PedalPC can supply 5 and 12 Volts DC (VDC) through its USB and automotive power sockets, respectively. (There is also a built-in 3-pin header reserved for powering a 12 V DC fan.)
If your device doesn’t have a power cord to fit either of these sockets, or it requires a different input voltage, you will need an adapter to connect it to the PedalPC.
There are multiple adapters available. What follows is a description of how to determine what kind of adapter you need.
Determing Input Voltage
The input voltage required by a device is usually shown on its label. Here are some sample labels from a laptop and a small battery charger:
If there is no label on the equipment, you can use the output voltage from the device’s power adapter label, since the device’s input voltage must match it’s adapter’s output voltage to work properly.
If neither is available (e.g., you are shopping for a new piece of equipment), you can usually find the voltage listed on the product web site or in the product manual under “Specifications”.
You can also tell a device’s voltage requirements by the type of power socket it has. All devices charged by a micro-USB cable, for instance, use 5V DC.
Choosing the Right Adapter
5V DC / USB Devices
Standard USB 2.0 power sockets supply 5V DC. The PedalPC has four such sockets built into the machine, one of which is used to power the PedalPC’s computer. You can use the other three to recharge a phone, tablet, or any similar device that requires 5V DC.
If you need to power additional USB devices, use a 12V-to-USB car adapter.
Each socket of a USB adapter can supply either 1 or 2.1 amps of current, depending on how it is designed. I recommend choosing adapters where all sockets supply 2.1 A, as they can power a broader range of devices and recharge devices more quickly.
12V DC Devices
Most monitors, small battery chargers, modems, routers, and some small computers require 12V DC. You can power these devices directly from one of the PedalPC’s power sockets. Each device will need a 12V DC car power cord with a automotive plug on one end and a barrel plug on the other. Barrel plugs come in a few different sizes; be sure to choose a cord with a plug that fits your device.
Devices Requiring > 12V DC
Other small computers and most laptops require a higher DC voltage, usualy between 16V and 24V DC. The best way to power these is using a DC-to-DC laptop car adapter. You can purchase adapters made specifically for your model of laptop, or universal adapters with selectable output voltage and power plugs that fit a variety of laptops.
Finally, some devices (e.g., most HP inkjet printers) have no extenal power adapter and will require a 12V DC-to-110V AC inverter. Inverters waste power (especially if they have a fan) and should be avoided if possible. The most efficient inexpensive inverters I have found are single-outlet, 75 W passively-cooled models like the one show below.
It consumes about 2.5 W with nothing plugged in.