• Insert one header from the top
of the board at E2 and F2. (You may
need to bend the LED slightly, so that
the header sits flat on top of the
• Turn the board over, hold it in
place with a plastic clamp, support
the header with a small piece of
scrap wood, and solder it in place
(using a minimal amount of solder).
• Insert the other two-pin header
from the top of the board at E5 and
F5, and solder the pin at F5 in place
using the same approach as the
previous instructions. Do not solder
the pin at E5 yet.
• Cut a 1/2” piece of thin
jumper wire (e.g., a lead from a
1/6W resistor), and use small needle-nose pliers to form a U-shaped bend
at one end.
• Crimp the U-shaped end onto
the switch pin at D5, and trim the
wire so that it just touches the
header pin at E5.
• Use a small screwdriver to
press the wire flat against the bottom
of the board, and solder it in place at
D5 and E5.
• Trim the soldered connection
at D5 as close as possible.
• Insert the completed power
supply onto a breadboard as shown
in Figure 4. If any of the solder
connections prevent it from sitting
flat on the breadboard, remove the
supply and further trim or file those
connections until the board can be
seated properly on the breadboard.
• Again, clean the bottom of the
board of any possible residue.
When you have completed the
USB female power supply, test it with
the USB power sources you intend to
use, and measure the voltage level to
make sure it’s less than 5.25V.
Developing a Micro-B
USB Power Supply
As we saw earlier in Figure 4,
both versions of our USB power
supply are very small, but I couldn’t
resist the temptation to develop an
even smaller supply. The type A
connectors that we used in both
stripboard projects are, by far, the
largest components on the boards, so
the obvious way to shrink the power
supply is to use a smaller connector.
At this point in time, micro-USB
connectors are just about universal;
almost all current cell phones and
cameras include a female micro-USB
type B connector, so that’s the one I
chose. However, micro-USB
connectors are far from “stripboard
friendly” because they are surface-mount devices, and their tight pin
spacing (0.026 inch) makes them
somewhat difficult (but not
impossible) to hand-solder. With that
in mind, I developed a PCB version
January 2015 17