Starting out in electronics we are quick to get excited about all the things we can accomplish, all the awesome automation we can produce in our lives, and all the ways we can improve the things around us. There are countless numbers of sensors, displays, motors, and lights.
Quickly we get wrapped up in laying out everything we need to make our ideas a reality but often a fundamental item is forgotten about until we have to put the idea into action. How the heck do we actually power this device we are trying to create? Apart from any other component there is none more essential than the power in electronics work. When putting together your home lab it helps to have a wide variety of options at your disposal and thankfully many of them can be salvaged from old electronics and obsolete computers.
The kinds of projects you need power for and the kind of power you need for them fall into a couple of categories; Low power for single board computers, mid-range for lighting and robotics, high power for heating elements used in home brewing. Single board computers encompass things like the Raspberry Pi, Arduino, BeagleBone Black, and the DragonBoard 410c. Most of these boards use 5V and generally up to about 2A with the Dragonboard takes a 12V input. For motor systems like those in robots or 3d printers you can see voltages range from 3V to 50V+ and currents can peak above 10A. A lot of the motor system power specs are determined by the system you have driving the motors and what those chips can handle so keep an eye on matching them up to the motors you want to use. Home automation systems blend the needs of single board computers with motor systems and add the need to handle battery inputs so they can be placed far from AC outlets. Once you get to looking at home brewing or other high power systems you have the lower power DC for controlling the system and then possibly a 5500W AC heating element to bring your mixtures to a boil. Creating your own 3d printer could require a DC source up to 300W for the heating element in the extruder.
For the low power projects using single boards computers a lot of times simple wall wart style power supplies will do the job just fine. I like to keep a variety of voltages and powers in my shop drawer to toss into projects. To be ready for most projects a 5V 2A and a 12V 1A supply will get you going. A lot of these come with a 2.1mm x 5.5mm barrel plug on the end which is common to single board computers, in some cases the power connector can handle 2.5mm x 5.5mm for flexibility. If the barrel plug isn’t what you need you can snip it off and strip back to bare wires that go into a terminal block or solder on a new connection just be sure to keep the polarities on the wires correct so you don’t blow up a board.
On a wall wart that has the conductors running side by side on the cable the marked or white wire is typically the positive line while the other is the negative. You can double check this with a multimeter before connecting it to your system to verify since there are some which are reversed. Whenever you are not 100% sure about a system it doesn't hurt to pull out the multimeter. The Mean Well GS12U and Artesyn DA12 are good examples of supplies that can be bought in either 5V or 12V styles. If these don’t meet your needs here is a link to all the options we have at Arrow.
As projects get more ambitious and demand more power you will move onto a larger brick that has a cord to the wall or may just use screw terminals for hooking up wires. Higher wattage power supplies come in a wide variety of voltages and currents to meet your needs and can feature multiple voltage outputs allowing for a 5V power rail to support the brains of the system and a 24V rail to power motors simplifying your power network. Running for long periods of time at full capacity, especially on high wattage supplies, produces quite a bit of heat that puts stress on the components and increases the chance of failure. To reduce the chance of failure over size the power supply by 10% to 20% reducing component stress and leaving headroom for load spikes.
The RWS300B12 from TDK-Lambda is a strong 300W supply with options that scale from 50W to 600W. The RSP series from Mean Well is another good option that scales all the way up to 3000W if you need a ton of power.
The above options for low and high power are useful especially since they can live with the project if it gets installed but to really complete a lab it is hard to beat the usefulness of a standard benchtop power supply. The benchtop power supply offers configurable outputs and potentially multiple outputs which are useful for getting systems up and running once they have been breadboarded. This flexibility does come with increased cost but the flexibility is incredibly useful.
The B&K Precision 1627A is a 220W single output supply that gives you a programmable output from 0-30V that supports 3A. The Rigol DP832 is a 195W power supply with three output, two ranging from 0-30V and the third ranging from 0-5V all supporting up to 3A.
There are a lot of options to power your designs and I hope the above helped layout a few that can get you up and running in your home lab to see you designs become a reality. The next step from here would be looking into DC to DC conversion which opens up options for using a single point of conversion from AC and still get all the voltages you need or making a system completely portable using battery power.