Electronic Project Plan Step 5: Enclose Your Circuit
Once your electronic circuit board is finished, the final step of your project is to mount it in a plastic, metal, or wooden box. You can purchase boxes specifically designed for electronics projects from most electronic parts suppliers.
If you don't want to spend the money for a bona fide electronic project box, here are a few alternative ways to find the perfect enclosure for your project:
Shop discount department stores for small storage boxes. You might find one that's just the right size and shape for much less money than an official project box of the same size would cost.
In the electrical department of any hardware store, you'll find inexpensive plastic and metal boxes designed for household wiring. Many of these boxes can be adapted for your electronic projects.
Before you throw away an old electronic gizmo, take a quick look at the box it's contained in. If you think it might be useful for a project someday, take it apart and discard all the innards, keeping only the empty carcass.
Be careful whenever you disassemble any electronic device. Make sure you have first completely removed the power source and watch out for large capacitors that may be holding on to their charge.
If you frequent yard sales, be on the lookout for items that might be useful as containers for your projects.
The inside of your project box may be completely smooth, or it may contain ridges or mounting studs designed to make it easier to mount components inside the box. If there are no such accoutrements inside the box, you'll have to devise your own method of attaching the various bits and pieces that need to go inside. Here are some tips:
You'll need a good assortment of small drill bits to drill holes through the box to mount your components. You'll need to drill holes to mount the circuit board as well such things as battery holders, switches, LEDs, speakers, and whatever else your project may require.
Make a good sketch of your project box and how its parts will be arranged before you start drilling holes. When you're sure you have everything laid out the way you want, use a marker to indicate the exact position of the holes you need to drill.
To mount the circuit board, use standoffs to provide some empty space between the board and the case. A standoff is a screw that allows you to mount the board so that it is raised above the bottom of the project box. You can purchase standoffs from any electronic parts supplier, but they are surprisingly expensive, often as much as 45 cents each.
If you have an ample supply of nuts and bolts, you can fashion your own standoffs simply by cutting a short length of plastic tubing — like 1/4″ drip irrigation hose — and feeding a long bolt through it.
Consider mounting the circuit board on the back of the lid rather than inside the body of the box. This sometimes frees up more room within the box for larger items such as batteries or a speaker.
Most switches can be mounted to a box by drilling a hole large enough to allow the neck of the switch to pass through. The switch comes with a nut that you can tighten over the neck of the screw to secure the screw to the box.
Some components don't have mounting nuts to secure them to the box. For them, a small amount of epoxy or other glue can help set the component in place.
Use stranded wire for connections within the project box. Stranded wire holds up better to the handling it occasionally gets when you open the box, for example, to change the batteries.