As intimidating as it might sound to build your own miniature Tesla coil, Id like to assure you it really is not all that hard. Here in lies all the simple steps that will eventually give your very own wireless desktop toy.
Just a note, in nature this is a easy to medium difficulty project. The biggest expense by far is time so get yourself a quiet spot where you may be able to leave things for a while and not bother people who may be using the space as well.
Step 1: The Setup - Gather Your Tools and Materials.
What you need-
A BD 135 Transistor, and a heat sink to get rid of some of that pesky heat.
-Resistor ( various types if you want, in my case testing from type to type I found that the 240 k works the best for me. The experience may vary from build to build.)
- Rocker switch
- 9V battery clip
- Wire, this is also up for debate I'm a firm believer in solid core wire but anything that is not too cumbersome will work just fine.
- last but not least is a perforated solder board, its not impossible to solder each part together without it, but bear in mind that you are going to have to pay special attention to the orientation of nearly every component making your life a lot more complicated.
As for the second part you are going to need :
clear casting resin
liquid rubber ( or any other molding material you have on hand)
a neon bulb
Or as a alternative you coil just use a cfl ( compact florescent lamp) which you can either buy or salvage.
What you may want but don't need -
The scrap wood box is a embellishment but it gives the final look something Id be willing to pull out in public. It takes time but is well worth the effort. But in the interest in time any non conductive container will work just fine.
A dremel with both a cutting bit and sanding bit.
Soldering iron and peripherals
drill and drill bits
90 degree straight edge
Step 2: Make Your Control Board.
This is by far the hardest part of the build, you are going to sit for a while so grab a cup of coffee and get ready to do some soldering.
the first step is to cut yourself a piece of perf the relative size that you need. 3 by 4 holes should more than suffice to fit all the components. Once you get more comfortable with how everything fits you can use a slightly cut board that's 3 by 3.
Note: I cheated a little, the transistor is surface mounted because I salvaged it from another boar which meant that I had a good deal of extra space on account of the fact that I did not use 3 of the holes. putting the transistor trough the holes means that the space will work out just the same.
the lane with the most components is going the collector which handles 4 spaces, however the secondary ( if you use a small-ish gauge) can fit in with either the led leg or the resistor.
Warning: before you get started make sure you understand the orientation of all the components its going to save you a lot of trouble.
-the first and foremost the primary is the coil has a top and bottom, working with a pnp means that the transistor needs a higher voltage on the collector than on the base which means you need to drive a positive current towards the gate. mixing up which side is up is going to result in the system not working. so remember induction is always in the opposite direction meaning that if your chip is connected to the bottom of your secondary the positive end of your coil should be at the bottom as well. ( also note that making the primary and secondary spiral in the same direction makes it a whole lot easier to figure this out)
- the second mixup happens because of the LED, its no huge problem just desolder and swap em round.
For this example assume that the silver side is facing away from you and make that you default position. The lane system works from left to right solder each component as explained ( 4th lane is the furthest right lane you have.)
no transistor connections here
connect a wire which is going to run to the rocker switch. ( this is also the positive battery connection)
one of the resistor legs
a wire to connect to the bottom end of the primary coil.
base leg of the transistor
place a wire which is going to be connected to the negative pole of the LED
later the secondary will be soldered to this lane as well so plan a head usually I just melt some of the solder from the other components in lane and make it share a hole with the resistor.
connect the second leg of the resistor to this lane as well.
collector leg of the transistor
connect the top wire of the primary coil here
this is the output otherwise known as the emitter
here you just need to connect the wire which is going to lead to the positive leg on the LED.
Once you have everything soldered you should have a board that has a bunch of wires sticking out of it.
Step 3: The Coils: Setting Up Your Primary and Secondary
Its at this point where you get a little more leeway. The secondary coil needs more rotations than the primary but after some experimentation I found that when using a 9v source after 200 turns on the secondary the range does not notably change. If at any stage you want to up the output its certainly going to have impact. This time around I used 4 rotations on the primary and 250 on the secondary and it worked just fine.
Right now I'm doing little more than gestimating how long the pvc should be then cutting off the excess after Iv done the winding.
Things to take into account:
- a small length of the pipe will go into the base so don't cut it off exactly at the start of your winding. ( usually 0.5 cm to 1 cm is enough space to work with.)
- to make things easier cut a notch where you start to put a starting length inside the pipe. This helps a lot for 3 specific things. keeping the wire in place while you wind, making it easier for you to count how many rotations have been done and finally allowing for easy access to the secondary.
- pre clean the ends for soldering, use a heat source and scorch a small length at the ends and either clean off the enamel with a knife or fine sandpaper.
More than that its just about sitting down and winding. Have a small patch of tape ready for securing the coil in place when your hands gets tired or if there are specific increments which you want to mark eg. every 50 windings.
The contraption in the pictures is just a assisting rig for which I will put a up a instructable soon.
Step 4: The Topload
The topload acts like a capacitor (kid of) which distributes the electric field more evenly. luckily you don't have to search very far to find one. The bottom of a can works perfectly. after the bottom is removed its highly recommended to sand down the sharp edges and also sand away paint left over from cutting and the manufacturing details on the bottom.
Step 5: Optional: the Box
One thing is certain, no piece of wood is made equal.
If you want to make a wood box from a solid piece of wood it can pretty much be surmised with these points:
- make sure its long enough to contain the 9V and its clip
- make sure it has the necessary depth
- cut holes for the LED, switch primary and secondary. I usually use a drill a hole and then expand it using sanding tools, this is however where improvisation works the best find what works and do it.
- varnish twice, the first coat should be heavily diluted with thinners ( its recommended that the solution should be about 30% thinner to varnish) . In between coats sand using a fine sandpaper to remove any stubborn particles.
Step 6: Testing
If you have a bread board you may at this point want to test the setup.
connect the leads to their components and add power.
If the led lights up then half the fight is already won. If it does not then check the setup.
the second part is to use the neon lamp, grab one leg and bring it close to the end of the coil on top. If it lights up you are good to go.
things that can go wrong:
the led poles are the wrong way around, just swap the legs and try again.
If neither positions work on the led then check the poles on the primary, the bottom of the primary should be connected directly to the positive of your power supply.
if there is still noting check for any shorts on the board.
If none of that works:
this is the worst case scenario, which mean that either the transistor is in the wrong orientation in which case I would suggest checking the data sheet. If everything checks out then there is a non negligible chance that the transistor is no longer with us. hold a small funeral and move on.
A good way to tell if the transistor is burnt out is to check if it heats up quickly , if it heats up too fast then you are either running current in the wrong direction or the transistor is dead.
In this circuit heat is a issue but it will never produce smoke, if at any point you see a white puff coming from the setup turn power off quickly.
Step 7: Finnish Up the Coil.
Gather all the components and assemble.
A small detail that was skipped earlier was the fact that the secondary was glued to the "lid" of the box, the space was snug but you don't want friction to be the only thing keeping it in place.
Its at this point where you may realize that the secondary needs to be soldered to the board. The secondary should be connected to there you can take two routes either you can loosen the solder on the resistor and make them share a hole or you can surface mount the secondary the board.
after the LED has be soldered you can secure it in place with some glue or epoxy. the rocker switch should be pretty sturdy ( depending on how snug the hole is) and may not even need any adhesive at all.
its at this point that 9V clip is inserted and also soldered in place positive going to the rocker switch and the negative going to the 1st lane ( the emitter leg of the transistor)
After those components are mounted and soldered go ahead and solder the primary coil's connection.
after which you can close it up and work on the top load.
Here all you do is lightly sand the area that you are planning to connect the secondary to and secure the secondary coils wire in place with a piece of tape. ( in this case its a piece of conductive tape) place some epoxy on the top rim of the secondary coil and secure the top load in place.
now all that is left is to add the 9V and test the switch and you are A- O- good
Step 8: That's the First Part Done.
Marvel, for you have tamed the wily forces of nature, using the excited electron cloud you can now power neon lamps and florescent bulbs wirelessly!
but the fun doesn't end there.
Step 9: The Proximity Light!
This is more of the point than the actual slayer exciter. How to use the energy effectively without user interaction. After playing around for a while you may notice that neon lamps don't work if you put it down,even on top of the coil.
what is happening is a fundamental principle of electrical current , voltage is described as a potential difference meaning that if there is no absence of electrons at a point no current will flow. Described in simpler terms no ground means light no go go. so when you have a neon lamp in your hand you act as the most negative point possible and thus set up a potential difference through the lamp making it light up.
the biggest problem here is to create a extremely negative point, several people suggested using a sheet of tinfoil which would allow for a greater potential difference which made things a great deal simpler, because all you need is a large surface area for electron emission. So using a coil and some conductive tape I was able to induce a constant potential difference when the cube was in the magnetic field.
if you do not want to spend the time curing the resin or messing around with the molds you can just solder the coil to a neon lamp and work from there.
the basic principle is that you need a surface that's large to emit electrons and another to conduct them from the coil.
Step 10: Getting Started.
I only had molding rubber on hand so I had no choice as to the material I had to use. If you are forced to use molding rubber take into account that when dried it has very little structural integrity being prone to being stretched. I used some cheese cloth to make reinforcing layers between coats it works well enough but is by no means ideal.
if you can use a alternative, liquid rubber requires too much attention and one of the solvents is ammonia meaning that you need to take into account ventilation.
Step 11: Finishing Off the Mold and Making the Resin Duplicates
So after the mandatory waiting period for the rubber to dry I demolded my cubes ( about 2 - 3 days worth of work and waiting) and added resin about 1/3rd the way in.
- I later learned that eyeballing it is a bad idea since you can easily overshoot what 1 third is and end up closer to half. the lesson here is try to be precise with certain measurements.
after that has dried add more resin to about full ( account for the fact that yo u are going to be placing a object in the mold as well) and wait untill the resin becomes a thick gooey consistency and place the neon bulb in the mold. and wait.
Step 12: Finish the Resin Cube
once you have the resin cube free you can start working on the last part.
so this part is where you can let out your inner artist. Personally I prefer coils so I found myself a thin pipe and wound some wire around it. I made a loop and soldered it to one leg. Meanwhile the other leg was taped to the side with the conductive tape.
Tada- go and give it a test.
Step 13: Job Done and Enjoy.
Enjoy your desktop toy.
Just some last notes :
-these things eat batteries like nothing, be prepared to swap them out on a regular basis.
-even with the heat sink things do heat up, so do not use it for more than 5 or 10 minutes at a time.
-shorting the coil will not result in any bodily harm however it will cause the battery life to be exponentially shortened.
If you make something awesome using wireless power and let me know.