- Hi, it's Matt.
With COVID forcing many of us to meet outside this winter,
I've had an idea.
Can I make this electric blanket
so then it can be powered by a USB battery bank?
(fanfare)
Before I start, I do not recommend doing this yourself.
Electric blankets do not have the best safety record anyway.
And yeah, this isn't advice,
this is just showing you my process as I try a thing.
I came up with this idea a few weeks ago,
while I was sat in a park with a few of my friends,
and we left because we were freezing our tits off.
And I was thinking, "What would help the situation
"would be an electric blanket."
But there's no power in a park,
and I couldn't find any battery-powered electric blankets.
So I thought, "Maybe I can make one myself."
So what I've got here is a 12-volt electric blanket
and it's designed to plug into your car
'cause your car's got a 12-volt battery in it.
Now, I don't wanna lug around a car battery with me,
they're way too big and heavy.
So let's get rid of that adapter.
So we're left with this power socket, and I was thinking,
"Well, I could find a battery that can plug into this."
And I had to look and they're all designed for caravans.
They're all this big and really expensive.
And then I remembered the kind of battery
that I lug around quite often, these USB-C ones.
- [Alex] But Matt, if it's designed for a car,
how are you gonna make it work with USB-C?
- Normal old-style USB power supplies
only output five volts.
This is a 12-volt blanket.
But we have a thing called USB-C Power Delivery.
You'll see so many more things
that are powered using USB-C these days.
And that's because USB-C Power Delivery
can output multiple different voltages.
Anything from five to, I think, 25 volts.
With normal standard power supplies,
you plug it in, and you get the power out of it.
It's that easy.
With USB-C power supplies, there's an extra step,
where the device plugged into it can talk to it
and request a specific voltage.
Now, this blanket's not designed to do that at all.
So I've bought an extra chip,
which I intend to build into this.
So then it can talk to a charger
and make it battery powered.
- [Alex] Okay. What's the plan?
- My plan is to see if the blanket works
and then see if the chip works.
And if they both do what I'm expecting them to do
then hopefully, I can tie the two together
and make it battery powered.
So let's see if this blanket works.
I've got a power supply here.
12 volts, just what a car battery kicks out.
And, ooh!
I've got a light.
There's a light on this temperature controller.
I don't wanna work on it while it's hot.
So I'm gonna turn it off.
Next, we've got this chip.
I've got a couple of different ones.
I need one that can output 12 volts or thereabouts.
If it's a bit more than it doesn't matter so much
because car batteries are known to output a little bit more.
I'd rather use the little one
because it's smaller, easier to fit in.
But if I need to use the big one, then that's also fine.
So the size difference is quite noticeable.
So let's get rid of the big one and let's try the small one.
So if I plug into the power,
I should be able to use my multimeter
to see what the voltage is.
(multimeter beeps)
Okay. That's outputting 20 volts.
So the little one's outputting 20 volts,
and I can see on the back of it, it says 20 or five.
There's a solder pad in here,
which I can solve it together to change.
So five is way too low.
20 is a bit high, but it might work.
Let's try the other one.
This one's got a button,
so then you can change the voltage that's coming out of it.
Okay. So that's kicking out five.
If I press the button, do I get anything different?
Nine.
15.
20.
Okay, so this one can do 15,
which sounds a bit more appropriate. (chuckles)
Let's see, if I turn it off and on again,
does it come back at the same voltage I left it on?
Do I need to press and hold that?
Just looking at the instructions for this chip,
so then I can find out the way
of setting the voltage on it permanently.
And a lot of them are very badly translated Chinese
but I found a post by Alex Whittemore,
which I'll link below, which has some English instructions.
So for 12 volts, I need it to be green.
Okay, so I plug it in while holding the power button,
the light flashes many colours,
and then I press it until it goes green.
So if I unplug it, will turn back on in green?
No, it's red.
It went green, red.
It's five.
I worked out why it wasn't working.
I don't think my mains power supply
that I was using to test can do 12 volts.
Yeah, it can't, that's why it wasn't doing it.
But now I've managed to set it.
I've got the green LED on it and on the multimeter...
12.1 volts.
Great. So that's what I want.
So I've got a USB-C trigger board
which can convert my battery
into the 12 volts that this blanket wants.
So now I need to connect this to the blanket.
Let's tidy up a little first.
Okay.
That's what I'm looking for.
Okay.
So the two cables for this
come out of the little plastic supported piece here
then I can feel them go in and then attach
to the heater wire that's going throughout the blanket.
So I don't think I wanna take this apart
'cause I don't wanna get close
to any of the heating elements and stuff.
So I'm gonna butcher the end of this DC connector
and then try to attach the USB trigger board to here
and then use a piece of heat shrink tubing
to insulate it all.
Yeah.
So I need to start by chopping up this cable.
Gonna need a bit of slack on the end of this
'cause I need to work out
which one the positive and negative is.
Oh, luckily they are coloured blue and brown inside,
which are standard colours for neutral and live.
But before I solder anything on that
I'm gonna try and kind of touch it together
to see if this turns on with the battery power.
So I've stripped my cables.
We've got a blue one and a brown one.
Brown one is traditionally live or positive
and blue is traditionally neutral.
Because I don't trust this,
I'm gonna test that theory. (laughs)
By opening up with a bit I've got left,
plugging it into some power,
and then seeing which way round there.
If I put them positive one in the brown
and the negative one on the blue, I should get to 12 volts.
If they're the wrong way around they should say minus.
That's plus 12.
Yes. Cool.
So that means brown is positive.
If I plug this in and touch these on here carefully...
Come over here.
We should expect to see the power come on.
So we've got blue on the minus, plus on the brown.
Yay! It turned on straightaway.
Yes!
Good. That means we're onto something.
Well, the next step's just to solder it up, I think.
We've proven the different parts.
Great.
This soldering iron's new. I haven't used it yet.
It arrived today.
But thanks to all of you who bought a Matt Gray T-shirt
or tote bag on The Matt Gray Shop,
I used that money to buy the soldering iron.
I need to rearrange some stuff here
because I need the soldering iron on my right
'cause I am right-handed.
I have prepared my cables.
Let's see if I can shove them in.
Will they fit?
Yes, I think they will fit.
Right. Let's tin the ends.
Which means putting a bit of solder
on the end of each of them.
Chop the ends down a little bit.
I'll do it with a point on the end
to make it slowly easier to shove through.
See if it fits.
Okay. I get each in.
Can I get them both in at the same time?
In we go. In we go.
There we go.
Great.
One of the hardest things while soldering
is tryna get your piece to stay the right way up
and not move while you're using.
Which would be easier if I had vice on me.
Or there's a device called helping hands
which some people use, I don't find them very useful.
Okay. That's the negative in.
Great!
Let's chop the ends off.
Let's see if it works.
Hopefully, I should just be able to plug it
into this USB battery, and it turn on.
Here we go.
Hey! It turns on immediately.
Right, there's one additional thing I want to do.
I'm going to try to remove this tiny little button.
So then I don't accidentally set the voltage
to something other than 12 and make this not work.
It's got some solder joints here and here,
on either side of it.
It's right next to two surface mount components
that I really don't want to take off
'cause there'll be an arse to put back on.
I think it's doable.
And if I break this now, at least I've got a spare.
Oh. Well, I've broken the button.
That'll stop it going.
Maybe let's do that instead.
Great, so I've successfully soldered the board
onto the end of the cable.
And I have removed the button
that you use to just set the voltage
'cause I want the voltage to remain.
So the next step is to put it
in a piece of heat shrink tubing,
to give it some protection.
And I need to get my heat gun to heat it up.
♪ I got tools, they're multiplying (chuckles) ♪
Heat shrink tubing is a type of plastic sheath
that shrinks when you apply heat to it.
So I've got a heat gun here.
(heat gun whirring)
Doesn't need to be too hot.
And you should see this start to shrink,
as a warm it up gently.
Okay.
Off you go.
Okay. That's it.
I think I've done it.
Let's try it.
So I've got my USB battery bank.
Turn it on.
Plug it into the power on here.
And you've got a power light.
I've pressed the heat button and it says it's heating up.
Now, we'll wait, I suppose.
The instructions did say three to five minutes.
So three to five minutes will have passed now.
Says it's doing it.
Oh! There's heat in here.
Oh. I can feel some warmth.
Yeah!
That means I've done it.
I've got a battery-powered electric blanket.
Bloody brilliant.
Yeah, it seems to be working.
Hopefully, it won't set me on fire or anything like that.
But at least when I'm gonna be using it, I'll be outside,
and with someone who can help me.
I would not recommend doing this yourself
just because I don't know how safe it is.
I've got enough knowledge to try it,
but not enough, I don't know, approve it. (laughs)
Thanks for watching.
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Thank you!
Oh, it's too hot. Oh!