I recommend the tesla coil science project

Big TC

There is a truly great article which was published
in the July, 1964 edition of Popular Electronics
magazine.

It's a 2 part article which gives complete plans
for building a small tabletop tesla coil, and a much
larger floor model!

The small one uses a TV flyback transformer, the larger
one uses a neon sign transformer.

I built "Big TC", and man, was it fun to have around!

It was too big to move when I moved away from
that city, so I took Big TC over to the high school
I'd attended and left it at their physics dept.

Right now, you can go on Google Images
and type in "July 1964 Popular Electronics"
and right there on Google will pop up the
pictures of the cover of that issue of that magazine.

Big TC uses no semiconductors.

Here is a clip of a big Tesla coil https://www.youtube.com/watch?v=RiwYvr7X0Yg
and an other one https://www.youtube.com/watch?v=VuP4KbUXACU



and a clip of a bigish bipolar Tesla coil solid state and computer controller. So it can make tones and music. https://www.youtube.com/watch?v=bTkjgBRiCsE

[Edited on 1/17/2020 by wg48temp9]

Quote: Originally posted by sodium_stearate

There is a truly great article which was published in the July, 1964 edition of Popular Electronics magazine. It's a 2 part article which gives complete plans for building a small tabletop tesla coil, and a much larger floor model! The small one uses a TV flyback transformer, the larger one uses a neon sign transformer. I built "Big TC", and man, was it fun to have around! It was too big to move when I moved away from that city, so I took Big TC over to the high school I'd attended and left it at their physics dept. Right now, you can go on Google Images and type in "July 1964 Popular Electronics" and right there on Google will pop up the pictures of the cover of that issue of that magazine. Big TC uses no semiconductors.

Lets see,




I got started with this back in the day




Was out of the back of popular science magazine all that send away stuff.

Quote: Originally posted by sodium_stearate

Yep. Tesla coils are a lot of fun! The modern versions all seem to use semiconductors of some sort in the primary circuit. I vastly prefer the much older and much simpler method. That method uses no semiconductors. That method only uses a capacitor, a spark gap, and the primary coil to create the high frequency oscillations. It basically is an RF tank circuit.

Quote: Originally posted by wg48temp9

Here is a clip of a big Tesla coil https://www.youtube.com/watch?v=RiwYvr7X0Yg and an other one https://www.youtube.com/watch?v=VuP4KbUXACU and a clip of a bigish bipolar Tesla coil solid state and computer controller. So it can make tones and music. https://www.youtube.com/watch?v=bTkjgBRiCsE [Edited on 1/17/2020 by wg48temp9]

What would have happened if YouTube was around when I got the Tesla bug ?

OMG or e-bay !




Oh my lord !!


[Edited on 18-1-2020 by Pyro_cat]

Quote: Originally posted by wg48temp9

Here is a clip of a big Tesla coil https://www.youtube.com/watch?v=RiwYvr7X0Yg and an other one https://www.youtube.com/watch?v=VuP4KbUXACU and a clip of a bigish bipolar Tesla coil solid state and computer controller. So it can make tones and music. https://www.youtube.com/watch?v=bTkjgBRiCsE [Edited on 1/17/2020 by wg48temp9]

Big TC

My version of the Popular Science's "Big TC" was
built on a 24 x 48 inch base made from 3/4 inch plywood.

There were two capacitors. Those each had a 24 inch
square piece of plain single strength window glass which
had 20 inch squares of galvanized sheet steel roofing
metal epoxy glued on both sides.

I had done lots of experiments making those capacitors
using aluminum foil taped and/or glued to the glass.
The big problem with using foil is that as it heats up it
starts to wrinkle, and that always makes a hot spot
and that will arc right through the glass.

Another variable with making those capacitors is that
during the startup transient, they can and will arc
clear around the edge of the glass. A 20 inch square
of metal centered on a 24 inch square of glass creates
a distance of 4 inches from plate to plate, going out around
the edge of the glass. You would not imagine an arc
could pop clear around that long of a distance, but it does!

Aside from that, the primary is 20 turns of heavy test-probe
wire would around a 10 inch diameter form. The secondary
of my coil was a single layer of #26 gauge enameled copper
wire wound around a phenolic tube 5 inches outside
diameter and 5 feet tall. Many thousands of turns.

It was powered by a 12,000 volt neon sign transformer.

It had an adjustable spark gap in the primary circuit.
Changing the spark gap distance tunes the resonant
frequency.

I still remember how awesome it sounds! When it's
in proper tune, that spark gap really talks up very nicely!
It makes a very loud sort of growl, with a hissing.
About 3/4 inch was the best spark gap.
There is no other sound like it.

On a cool, crisp, very dry winter day, I could easily
draw 14 inch arcs off the top ball, to my hand.
Then with the other hand I'd reach out and zap
an innocent bystander by giving them about a half inch
arc off the end of my finger!

That thing was a real chick-magnet, let me tell you...


[Edited on 18-1-2020 by sodium_stearate]

Quote: Originally posted by sodium_stearate

My version of the Popular Science's "Big TC" was built on a 24 x 48 inch base made from 3/4 inch plywood. There were two capacitors. Those each had a 24 inch square piece of plain single strength window glass which had 20 inch squares of galvanized sheet steel roofing metal epoxy glued on both sides. I had done lots of experiments making those capacitors using aluminum foil taped and/or glued to the glass. The big problem with using foil is that as it heats up it starts to wrinkle, and that always makes a hot spot and that will arc right through the glass. Another variable with making those capacitors is that during the startup transient, they can and will arc clear around the edge of the glass. A 20 inch square of metal centered on a 24 inch square of glass creates a distance of 4 inches from plate to plate, going out around the edge of the glass. You would not imagine an arc could pop clear around that long of a distance, but it does!

Quote: Originally posted by sodium_stearate

Aside from that, the primary is 20 turns of heavy test-probe wire would around a 10 inch diameter form. The secondary of my coil was a single layer of #26 gauge enameled copper wire wound around a phenolic tube 5 inches outside diameter and 5 feet tall. Many thousands of turns. It was powered by a 12,000 volt neon sign transformer. It had an adjustable spark gap in the primary circuit. Changing the spark gap distance tunes the resonant frequency. I still remember how awesome it sounds! When it's in proper tune, that spark gap really talks up very nicely! It makes a very loud sort of growl, with a hissing. About 3/4 inch was the best spark gap. There is no other sound like it. On a cool, crisp, very dry winter day, I could easily draw 14 inch arcs off the top ball, to my hand. Then with the other hand I'd reach out and zap an innocent bystander by giving them about a half inch arc off the end of my finger! That thing was a real chick-magnet, let me tell you... [Edited on 18-1-2020 by sodium_stearate]

Quote: Originally posted by Morgan

This was an inventive variation for making sparks. Wehnelt Interrupter https://youtube.com/watch?v=m87-paje-ZI

This is going to take me a bit to get but cool. How the heck does that work ??

Let the web searches begin !