Enclosures for DIY Electronic Projects

Construction

• Enclosures must have dimensions appropriate to the project. While it is obvious that they cannot be too small, it is equally important that they not be too large, so that project can fit into the space it is designed for. An example of such a specification is where the completed project should have the ability to be placed inside a wall opening. Enclosures must also be sturdy enough to protect the project from breakage due to dropping or vibrations. The cases may be made from one part, or they may be constructed from several parts held together with connectors such as screws or snaps.

Thermal Considerations

• Containers have to help ensure that the components do not become overheated, and thus the flow of air inside the project may be a concern. Airflow may be controlled by the use of holes, vents or fans inside of the container, and the use or non-use of lids. Lids not only help with airflow, but they help protect the circuit from dust, liquids and other forms of contamination.

Materials

• Plastic cases are typically used for low voltage circuits, and metal ones for high voltage circuits. Plastic casings are typically made from polystyrene, ABS or polycarbonate. Polystyrene is the most commonly used plastic, and it is made from liquid hydrocarbon. ABS is a thermoplastic, which means that it can turn into a liquid when heated sufficiently, or it can turn glassy when frozen. It is stronger than polystyrene. Polycarbonate is also a thermoplastic, and it is made using carbonic acid. It is heat and shatter resistant. Common metals for enclosures include aluminum and sheet metal. Metal housings are used for power supplies, surge protectors, switches, and outlet receptacles. For high voltage sources, aluminum boxes should be grounded, which means zero voltage. This is done in order to prevent electrical shock. Grounding involves attaching a wire from the circuit either to the chassis, or to a pipe that is connected directly to the Earth.

Shielding

• EMI is an acronym for electromagnetic interference, and it is especially a concern for circuits that are portable or wireless. RFI means radio frequency interference, and it is part of the EMI spectrum. EMI/RFI is caused by signals or noise from other electronics, such as high-frequency radio signals from cell phones. Metal enclosures can guard against these effects. Alternatively, plastic enclosures can help prevent them with the use of metal shielding made from paints or plates.

DIY Enclosures

• Cases may be purchased, or built from scratch. Another technique is to modify ones that were originally used for other purposes. Hammers, drills, and mini saws may be used to do the modifications. Containers that can be adapted include DVD cases, cigar boxes, empty remotes and sardine cans.