by Gerard Fonte
Make Your Own Custom
A Simple — Yet Effective —
Way to Dress up Your Projects
Membrane switches are useful for a number of
reasons. They're thin, water resistant, and can
be customized. Unfortunately, custom set-up
costs are high and take a lot of lead time. This article will
show you how to make your own custom "pre-produc-tion" membrane switch quickly and at very low cost.
There are many variations that you can do, so use this
as a starting point and follow your imagination. Figure 1
shows the basic idea of how this works.
Figure 1. Here is the basic approach for the membrane
switch. The paper overlay is protected with package sealing
tape on the top, and attached to the front panel with
double-sided tape on the bottom. The PCB is mounted
with spacers so that the top of the switch actuator is
even with the top of the front panel.
What You Need
Photo 1. The basic parts needed.
Photo 1 shows the basic parts needed. The Printed
Circuit Board (PCB) in the lower left has just four switches on it. These switches must be the very common
"membrane" push-button type, but the housing can vary
(more details on this later). Typical switches are shown
to the right of the PCB. You will also need the overlay
graphics (upper left). This is just a piece of paper with
whatever you want on it.
Obviously, the push buttons on the overlay must line
up with the PCB switches. I also make a second "work
overlay." This has the mounting holes for the PCB and
front panel (lower right). This makes alignment much
Generally, this paper overlay is created with whatever computer software graphics package you have.
Although, you could do it by hand.
The "special" items you need are two-inch wide
transparent package sealing tape and double-sided cellophane tape. Both of these are available at any office
supply store. You don't really need the package sealing
tape dispenser (about $20.00) but it makes things much
easier. You'll also need basic hand tools and a drill (a
drill press is much easier).
Drill the Front Panel
NUTS & VOLTS
The first step is to drill the front panel with holes for
the switches and mounting holes for the PCB. You need
to provide good alignment between the overlay, front
panel, and PCB. Photo 2 shows the paper work overlay
attached to the front panel with a couple pieces of double-sided tape. The center points of the switches and
mounting holes are center punched through the paper.
Note that the tape extends beyond the front panel.