FORGEThe other item we need for the build is a 12 V power
supply (we pulled this from our big box of spare power
supplies) – the only requirement is that it can supply
just over 1 A of current (1 A for the head pad, and a
bit for the controller). A 1.5 A power supply should be
plenty. We attached this via a 5.1 mm jack, but you
could also wire it directly in if you’d prefer.
That’s all the electrical gubbins sorted; we just
need a box to house it in. As we’re trying to hold a
warm temperature, we need insulation to help it stay
warm so we don’t waste electricity. Insulation also
helps keep the temperature even inside the box.
There are a few options here. The simplest is to use
an insulated box like a cool box, but this is also the
most expensive option. The most hacky solution is to
use a simple Tupperware box, and wrap it in a blanket
when it’s running. However, we opted to build our own
insulated box using two plastic boxes, one smaller
than the other. With the small box held inside the large
box (more on this in a bit), we filled the gap between
them with insulation. There’s loads of stuff you can
use for insulation, but we used old plastic packaging.
Anything that can be scrunched up and cut to size can
be jammed between the two boxes to help keep our
heat in, and our insulation consisted of everything from
bubble wrap to (clean) crisp packets. We used scissors
to cut it all into little bits, and jammed it in place.
Above
The wiring for our
box puts the relay in
line with the power
for the heat pad
Left
The temperature
controller displays
both the current
temperature and the
desired temperatureTHE BUILD
The first part of the build is to get the electronic
gubbins mounted into the outer box. The temperature
controller is panel-mounted with clips to hold it
in place, so you need to cut out a rectangle the
appropriate size from the outer box. We used a rotary
tool with a cutting disc, but a hot knife would also do
it if you don’t have a rotary tool. You’ll also need a hole
for the power to go through (we used a panel-mounted
5.1 mm jack port; you could equally just have a hole for
the wires to go through, but you may want to consider
using hot glue as strain relief if you do this (this will
also help with insulation).