Hi Gang! In a previous video I showed you wireless
transmission of electricity using the popular joule thief circuit.
I demonstrated it powering an LED and a buzzer, even with the transmission coils hidden inside
a drawer and the LED and buzzer on top.
In this video I'll show you how you can make it too.
It's basically the joule thief circuit, which looks like this.
One difference is that the small transistor is upgraded to a power transistor.
And the other is that the usual toroid with coils around it
is replaced with this big, flat set of coils. To transmit energy electromagnetically like
this we're creating a big fluctuating electromagnetic
field which things can take energy from.
This is a coaxial cable, a cable with two wires in it, sort of.
One wire is a solid copper wire running down the middle.
The other is a mesh of thin wires surrounding that
along its entire length. So there really are two coils here.
This design for two coils is perhaps most popularly known
from this patent of Nicola Tesla's, though there it's used for a different purpose.
The inventor of this joule thief/electricity transmission trick
is YouTube user slider2732 and he calls it the Simple Wireless Electricity
System.
So the first step is to make the big coils.
I start with a large piece of cardboard, and attach clear packing tape to the back.
I then attach strips of duct tape to that packing tape,
such that the sticky side is facing upward on the ront of the cardboard.
The clear packing tape is just so that I can remove the duct tape later
without tearing off pieces of cardboard along with it.
I keep filling it with duct tape with the sticky side facing up
until I've made a large enough area for the coils.
For the wire I have this scrap coaxial cable someone had thrown out,
around 45 feet or 14 meters of it.
Stripping one end you can see the copper wire on the inside
and the mesh of wire wrapped around that. These wires will need to be connected to the
coils at this end. I solder them before winding the coils
since it would be harder to do after the coils are made.
The outer, mesh wire can be hard to solder to,
so one trick is to twist the wire with the mesh and then solder it.
Then it's time to start winding the coils. I start at the middle
and press the cable down to the duct tape as I go.
Notice that I added more tape to the ouside so I could use all my cable.
Once I run out of cable, I bring up the four side tapes,
and cut off the excess. And here are the finished coils.
But this cable's fairly stiff and after a few days,
much of it has pulled away from the duct tape underneath.
I later found a nice trick to prevent that and that's to cover the whole top surface
in clear packing tape.
Slide2732 used super glue and the small test I did showed it would work
with my cable too.
I also tried using hot glue but my stiff cable pulled that apart.
But it might work with speaker wire or other more flexible wire.
Next comes the rest of the joule thief circuit. For that I need a power transistor,
like this 2N3055. I'm expecting to need some resistance under
1000 ohms so I have this collection of resistors
and a 100 ohm potentiometer to try. And I have 4 AA batteries connected in series
for around 6 volts.
Once again, this is the circuit diagram. And here it is all on a breadboard,
and connected to the transmission coils as per the diagram.
The tricky part for people new to this sort of thing
is figuring out the transistor. It has three places to connect to,
these two legs and the case itself. Notice that the legs are nearer one end than
the other end. This one is called the emitter
and this one is the base. The case itself is the collector.
So I put the two legs in appropriate holes in the breadboard,
and use an alligator clip to connect to the case.
Before I can test it, I need a receiver coil to test with.
For that I lay out some overlapping strips of clear packing tape
with the sticky side facing up. Some pieces of other tape hold it all down.
I start with a small loop at one end of a long wire,
and press it into the sticky tape. I then start winding the wire onto the tape,
pressing it firmly to the tape as I go along. I don't have to,
but I use the same winding direction that I wound the big transmission coils.
It took a few extra pieces of wire twisted together
but I stop when I have a fairly big diameter, 11 centimers or 4 1/2 inches in this case.
The length of wire is around 6.1 meters or 20 feet.
I then put packing tape over the top of the coil,
and cut it out, making sure I leave enough tape around the
edges for the bottom and top tapes to stick together.
The receiver coil is done!
Here's another one I made, and from the two colors of wire you can see
I definitely had to twist multiple wires together to make up the length.
And here's another one done using the same taping technique
by making a rough spiral out of uninsulated thin wire.
Pretty much any wire will work with this technique.
My first test load is an LED. I attach the long leg,
the positive or anode, to the outer end of a receiver coil
and the short leg, the negative or cathode,
to the inner end of the coil. If that doesn't work for you then try it the
other way around. If you have two LEDs then you can connect
one one way and the other the other way,
so that at least one of them will light up. That's a trick I learned from YouTube user
MongrelShark.
I sit the receiver on top of the big transmission coil,
connect up the positive of the battery, and the LED doesn't light up.
I increase the resistance by turning up the potentiometer
and it lights up, but only briefly.
After some testing I find that if I replace the 100 ohm potentiometer
with a 470 ohm resistor, and plug it in,
it works great, and with a good wireless transmission range.
And here it is with another receiver and LED and with a receiver with a piezo buzzer.
Putting an ammeter inline with the input you can see there's quite a current draw,
around 700 to 800 milliamps.
To save on batteries I bring out my homemade 0 to 24 volt DC power
supply.
One thing to check is if the transistor gets hot.
If it does then you could try mounting it on a heat sink.
If you don't know how to do that then see my video on how to attach a transistor
to a heat sink.
I decided to try a smaller transmission coil. Instead of a coaxial cable
you could instead use speaker wire cable since there are two wires in it,
or a two wire power cord from an extension cord
or the plug for an appliance. Or you could wind two single wires side-by-side.
Use whatever you have handy.
Here I have some telephone cable which has 4 wires inside it.
If I connect the red and black together and the green and yellow together
then I have the equivalent of a 2 wire cable.
Using the same sort of trick as I did with the receiver coils,
I lay out some tape with the sticky side facing up.
I did some calculations in a speadsheet to get an idea of how big the resulting coils
will be but you can also just do trial and error too,
laying down more tape as needed. You can find that spreadsheet on my webpage
all about this wireless electricity transmission. There's also a link to it in the video description.
I start a loop at the middle but with a length of wire sticking out for
connecting to later. Once it's all wound, I put tape on top too.
I then tape down the wires going to the center such that they end up near the outer wires.
I connect it up as per the circuit diagram and try it.
And finally to get the circuit off of the breadboard.
I've cut a piece of plastic from some scrap, and drilled some holes.
The transistor goes in first. To hold it in place
I put a small bolt through one of the holes in the case,
which is also the collector, and attach a wire to it at the same time as
I tighten the nut.
Then come some wires for going to the power source,
the batteries or other power supply. I solder the black one, the negative, to the
transistor's emitter.
Then I push through the resistor, and solder one end to the transistor's base.
That leaves connecting up the transmission coils.
I start with the inner wire of the coaxial cable
at the center of the transmission coils going to the other end of the resistor.
Then I use a short red wire to connect the other end of that inner wire
to the red wire from the power source, the positive.
The outer mesh of the coaxial cable at the center of the transmission coils
also goes to the red wire from the power source. And lastly,
the other end of that mesh goes to the collector of the transistor.
Done!
And here's the finished result in action.
And here I put it in a desk drawer,
to power things on top, looking like magic.
Well, thanks for watching!
See my youtube channel, rimstarorg for more neat videos like this.
That includes one on how to make a simple joule thief circuit to power
an LED. Another on using the joule thief circuit
to power a compact fluorescent lightbulb. And for variety, how to make a pyramid hologram
and how it works.
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See you soon!