A cheap chinese soldering iron
which I got because I thought,
"Well what can you get for 99 p?"
and it uh
another thing that stuck out was the fact
it wasn't earthed which wasn't a very good thing
given it's got a very hot heating element at the end
and you know, heat degrades insulation and so on
And this got off to a really bad start because
just before I'd even started this video
I just saw that, y'know, it's got this huge hole at the end
with the wires up it and I thought
"is there any strain relief?"
and I pulled it and
and it just went
*pop*
and the wires just came out
so um
right!
so uh this one came from eBay
a seller called
pfft, blimey...
dhane_rajan
D-H-A-N-N-E understroke R-A-J-A-N
and it cost 99p inclusive so
lets not have too high an expectation(!)
Now I wouldn't use it on electronics stuff because
obviously you want
it's better to have a grounded tip
for static reasons
and safety reasons as well
but maybe it's okay
if you're willing to overlook the complete lack of earthing
for just doing basic electrical connections
and stuff like that
but anyway lets uh
open it up
so um
no solder connections
it's just um
the usual arrangement, I think, of
the connection wire being twisted with the actual resistance wire
and presumably this is some sort of strain relief system
that that wire was supposed to be zig-zagged round it
I'm not 100% sure
and then wedged down there
but it didn't seem to make a very tight fit into it
so erm
it didn't
erm
what's the resistance value of that?
it's supposed to be uh
220 volt 40 watt
so let's do the maths with that then
and uh see what sort of resistance we're expecting
if I can find the calculator, where's the calculator?
I put the calculator down...
have I lost the calculator? there it is...
so uh
I equals P over V
so we're looking for...
40 watts divided by
220 volts
oops
40 watts divided by
220 volts
so we're looking for a current of
about 180 milli Amps
R equals V over I
220 volts divided by
0.18
we're looking for a resistance
of about 1.2 k
so lets uh
turn this to 2k
and my finger resistance won't be too significant
so I'll just hold the wires on
ehh... 1.8 which will probably fall
uhh, as it heats up a wee bit
yeah that's OK that's reasonable enough
erm
ooo-kay
right
Here in the UK just the bit for this soldering iron
would probably cost more than this whole soldering iron
costs so it was quite short
guessing this comes out completely
does this just hold the whole assembly in the end?
it'll be quite interesting to see what sort of insulation there is in here
this is proving...
not quite sure how the guts are held in this
lets try sliding this up...
is that going to release it?
oop there we go, there we go
is that the heating element ?!
wrapped around that?
is there insulation in here?
that can't be the heating element is it?
there's a wire tucked underneath and running up
but it's underneath it
and that's exposed that can't be the heating element can it(?)
lets double check that with the resistance
oh no that's not the heating element
that's just a dead short
so that..
hmm sudden jump because the iPad
ran out of memory apparently
and just decided to stop recording without any warning (!)
anyway! uh
the construction was such
the
wire that I just measured the resistance of there
was just a steel wire that was
basically they've run it down
uh
from the top there
to the bottom
and then wound it round upon itself
and then wound it up to the top and then twisted it back on itself
and the whole purpose of that was to hold on a layer of
this sort of strange plastic-y mica insulation
it's very plastic-y!
Very odd!
So there was a layer of the mica insulation
over what turned out to be erm
one layer over the whole lot
then another layer to separate the return wire
from one end of the heating element
from the rest of the heating element
and then finally
the heating element wound round a layer of mica
that was directly on this
the support for the soldering tip
and it's interesting that
initially what I thought is there any risk that the soldering tip could drop down inside
and short those wires out
but if it drops down it's stopped
the end is just pinched in so it can't theoretically fall though
I suppose you could put it in the wrong way around?
nyeehh?
but anyway uh
I still don't much fancy the fact it's not
got earthing on the barrel
that would have made it a lot better
in my thoughts
it's quite an interesting construction
the multiple layers
basically three layers of mica
then held in place with that outer section of the wire
it's neat enough
but as I say I wouldn't trust it from an electrical safety perspective
by our electrical standards, because
I just prefer something like that to have an earth
connection onto it just in case
something, you know, a fault in manufacturing
or just the insulation broke down with the heat over time
but interesting to take to bits anyway