3.5
Powering the board from the USB port
In some applications, you may find it convenient to power the QLG2 board from the USB
port.
In this case, simply solder a jumper wire across JP11 as shown in the diagram below.
Tip: I am in the habit of making my soldered jumper wires as a little loop, standing up about
5mm from the board surface; this is because even if I am 100% sure now, that this will be a
permanent connection... all too often I find for whatever reason, I will change my mind later.
To make it easier to remove, or to temporarily disable, a jumper wire – I just make a 5mm-
high loop rather than a wire laying near the PCB surface. The 5mm loop is a lot easier to
cut and if necessary, to remove, than a wire tight flat against the board surface.
If you already feel now that it will not necessarily be a
permanent connection, then fit a 2-way pin-header
and use a header jumper, as pictured (right).
Now you might be thinking, "I have pin headers, but I
don't have those fancy jumpers you used to find (and
maybe still do) on old PC Motherboards, and I don't
fancy waiting for Amazon, eBay, whoever"... well
never fear, for necessity is the Mother of invention – I
don't have those fancy jumper plugs either, I just
improvise using female pin header connectors. Which
aren't even the right right size (2-way) but can be cut
to leave just two pins... and then gently bend over the
two pins towards each other and solder in the middle
(see photo, right).
IMPORTANT: never connect the jumper to power
from USB, and at the same time supply +5V power
from some other source to the other connection
pads! NEVER, EVER!
10
QLG2 manual for firmware 1.00a