Details of my Tesla Coil

Posted by HELiX

After over a day of mugging Tesla Coil theory and construction, I’ve come up with a report for starters:

Overview

The ‘Tesla Coil’ is a device invented by the brilliant scientist Nikola Tesla (1856 -1943). It is a high voltage, high frequency, power generator, primarily built for conducting experiments and to observe phenomenon associated with alternating electricity. With this coil, Tesla was able to generate voltages of such magnitude, they would shoot out of the apparatus as bolts of lightning!

The sight of writhing streamers of electricity jumping though the air is certainly spectacular. Today, Tesla Coils are built by amateurs all over the world for one reason only, the thrill of making your very own Lightning!

Personally, I actually think that Tesla Coils are popularised in Singapore either through the demostration at the Singapore Science Center, or that you’ve actually played Red Alert. I’m proud to declare that mine is the latter.

Red Alert 2’s Telsa Coil:

Construction:

The construction of a Tesla Coil isn’t as easy as it seems. It is costly, dangerous and requires a lot of motivation. There are technical skills involved and a good knowledge in physics and mathematics is essential. It is best that we break down the construction into the different components.

Power Supply/Transformer

Perhaps the most important component of a Tesla Coil is the power supply, and probably the hardest to obtain. It’s the single most important component as it affects all the other components and the overall size of the Tesla Coil.

It basically converts the voltage from the mains (240V) to the extremely high voltages needed.

Generally, amateurs look for a few type of transformers.

Neon Sign Transformers (NSTs) are probably the most popular. They can be obtained from neon sign shops. The cost can be from $30 to over a $100, depending on the condition and ratings. They are generally ranged from 6kV to 15kV, with about 30mA. There are 2 kinds of Neon Sign Transformers, one of them are Iron cored and run at 50Hz, the other are the new smaller switchmode ones which run at 20kHz and are a lot lighter. The heavy iron-cored ones usually perform better.

The ultimate transformer would be a Pole Pig. These are used by your local government agencies to delivery the power to the city. They can be found, well, up high on the poles that delivery your electricity. They weigh about 200kg, so be prepared with a crane or something. Also, you might want to have an electrician with you, as your circuit breakers will blow easily due to the high current these fellas require. So do not bother.

I called up a Neon Sign shop, and they indeed had used/old NSTs for sale. I visited them and got one of them at $45. If you do not know how to operate one, it’s best that you ask the shop to demonstrate. They’re deceiving small; They weigh quite heavy, coming in at about 8kg to 20kg, and my arms were sore after carrying it home on public transport.

First, some details of my transformer, along with the specifications my tesla coil has to meet.

My NST outputs 15kV and 30mA.

Going into further details…

Using this formula, I worked out that my Tesla Coil can achieve spark lengths of up to 91.64 cm.

Each tesla coil has to have a capacitor bank. This stores the power needed for the Tesla Coil to discharge. Three types of capacitor banks can be made, including a completely home-made one consisting of beer bottles and some stuffs. But the easiest method would be a Multi Mini Capacitor (MMC) design. A lot of factors has to be considered for the MMC.

First, you gotta know the peak voltage the capacitor bank has to handle.

While my transformer outputs 15000V, the voltage is able to peak up to 21213V!

Then you have to choose the type of capacitor.

I chose a 1500VDC, 0.047uF Polypropylene Capacitor because they’re the the most value for money, ie. best uF per dollar.

Now because my MMC has to store 21213V at least, I figured that the voltages have to be splitted by the capacitors when they’re placed in series. I plan to arrange 15 of these caps in series, adding up to a total of 22500V it can handle.

Using the formula above, I calculated that my transformer requires a capacitor bank of 0.0064uF. However, this is merely the Resonant Cap value. To be on the safer side, we would want a LTR (Larger-Than-Resonant) value. This value is dependent on whether you use a static spark gap or a SRSG (Synchronous rotary spark gap) which I will elaborate more later. I will be using a static gap, so the LTR value is 0.0095uF.

The calculated total capacitance of 1 ’string’ of 15 caps is simply, the rated capacitance of each cap (ie. 0.045uF) divided by the number of caps in the string (ie. 15), so each of my string has 0.00313uF. To produce 0.0095uF, I would need roughly 3 strings.

So it’s 3 strings of 15 caps, giving a grand total of 45 caps needed.

For each cap, a resistor has to be attached as well. Bleed resistors are employed to safely discharge each capacitor to allow for safe handling while tuning and transporting the coil. I chose a 10MOhm 0.5W 3500VDC resistor.

The overall design for my capacitor bank is as follows: (Click to enlarge)

…

That’s all for today! I should receive the caps and resistors in my mail tomorrow!

Comments(0) 7:25 PM 3 March 2007

Choosing the Right MMC

Posted by HELiX

Okay, I’ve decided on these for my MMC (Multi-Mini Capacitor) Bank.

After some calculation, it would require 0.0095uF and at least 21213V.

I just made a mail-order for $110+ worth of electronic components, which include these:

50x of Polypropylene Capacitors
1500V each
0.047uF each

50x Resistors
10MOhm
0.5W
3500V DC

The design is as follows:

Click for bigger image!

Comments(0) 5:23 PM 3 March 2007

Impossible Muggers

Posted by HELiX

Muggers are a subject which I find really fascinating.

Since today.

Because today, I tried to be a mugger. I spent the entire day, roughly 11-12 hours, reading up on Tesla Coils. I mean, it’s 15000 volts we’re dealing with here, and electrocution isn’t the nicest way to die.

I am lifeless. You could say that.

Towards the night, I started doing calculations of the prices I have to pay for each component.

… And the multi-mini capacitor bank came up to be $700+ over, with nearly 500 capacitors.

I was like, OH CRAP NOW I GOTTA DUMP THE PROJECT.

I spent 3 hours searching for alternatives to the project, and just a while ago, I figured I did this:

My capacitor bank requires 0.0095uF. I wrote down 0.095uF.

I’d be paying for 10 ten times the required amount.

And yes, that’s 3 hours once again. I feel so stupid now.

Grr.

Comments(0) 3:08 AM 3 March 2007

Um, TODAY Part #3

Posted by HELiX

I’m gonna complete today’s trilogy of entries.

And this gonna be the best one yet! I hope.

Because, because- I OFFICIALLY EMBARKED ON THE TESLA COIL PROJECT!

Here’s what I’ve managed to achieve so far:

…

…

…

COOL YEAH?

Just kidding =(

But seriously, I hope to achieve that after mine is completed.

This is what I’ve really got so far:

You can call it a really uninteresting box, because perhaps it really is.

Hm.

Beautiful thing ain’t it? But they say, beauty is only skin-deep. Inside lies a monster that’s… another beauty. Crikey.

Woo-yeah! A Neon Sign Transformer. 15000 Volts of sheer fun. 30 milliAmps of high electric bills. But hey, I get to go over to Lil’ Nicholas’ house for the testings, so guess who will be having their circuit breakers tripped and electrical bills go astronomical? Oops.

I think the clear and present danger here needs even clearer perspective. 15000V? I think you can appreciate that. Our mains use 240V. 30mA? How’s this for starters:

1MA = Tingling feeling

5MA = Pain

6MA = Female let go

10MA = Paralysis/male let go

15MA = Hazardous

30MA = Breathing Stops

75MA = Ventricular Defibrillation

Stun guns use about 1-2 mA, 3-4mA for the sadistic ones. 30 mA is possibly fatal, although it wouldn’t be instant death.

And thus begins the story of Derek’s trip to purchasing a 15000V transformer!

…

STORYTIME!

Okay, so right after bowling, it was like 5+ or 6+, I don’t know, but since I was already in the Bukit Gombak/Batok area, I knew the Neon Sign shop was nearby.

Kok Hong said he could point me in the correct direction by doing just this: He asked me to go to the nearest bus stop, check the information of the buses’ routes on the boards. We left our separate ways and when I reached, I didn’t see any info. NICE ONE LAH KOK.

So instead, I took out my Dopod D810 and activated the GPS! *insert the James Bond’s tune for whenever he flashes his gadgets* With no idea what bus to take, I followed the GPS map… and the Neon Sign shop was a good 3 km away. Great.

What the heck, it was getting late, so I ran. Yes, I ran, following the GPS CAR navigation system on my PDA Phone, for the entirety of 3 km. I had that slightest weird feeling that the shop was already closed.

Ahh, then eventually I reached! The feeling of seeing that building after the 3 km run was truly sensational.

And then I stared at the building. It was an… INDUSTRIAL BUILDING. You know, not your shopping malls or whatsoever. This building had security, and is for factories and those kinda stuffs. INDUSTRIAL BUILDING Y’ALL. With no windows and stuffs.

Try to imagine this: BP’s D&T room, multiplied to an entire building for tens of companies.

I casually walked in, guard didn’t see, reached the lift, checked the location of the Neon Sign shop in the building. Obviously, by now, I realised it isn’t a retail shop, but a machine shop/office. The whole damn place was eerie. Really. Silent corridors of an old building, and the offices… have no windows. I finally found the Neon Sign office and went in. Here’s a small portion of the place that I took. It’s much bigger than what you see.

I saw two ladies, told them I was here to purchase a Neon Sign transformer, and one of them immediately helped. I said I called yesterday about the transformers, and I need to purchase one for a school science project. Which is completely utter bullcrap.

She brought me into the machine shop where they did their Neon Signs, and into a store room. They had one entire stack of used/old transformers, and I agreed to take one of them.

Not that I wanna imply anything here, but the lady was really nice for someone working at this kinda industrial place. She was extremely, extremely helpful. When I called them up, I was made to speak with a man who was an ass. He kept doubting me, asking me about my school and the project. Later, I found out that that guy was the boss.

Apparently, they close at 6.30pm. I reached at… say, 7pm? The boss already went home, and these employees are left behind to finish up their work before they leave, and that doesn’t happen often. I won’t be seeing them in ‘Fortune’s 100 Best Companies to Work For’ anytime soon. Fortunate for me, I didn’t have to meet their ass-ing boss. Reaching there late was actually a good thing.

The lady asked a bit about my project and school, but at least she trusted everything I said.

I such a liar =(

Ya, then I asked whether the transformer’s working, and she said she’ll get one of ‘her boys’ (to quote her) to test it out. One of those… manual labouring worker guy came, and the lady had him to teach me how to fix up the transformer to the mains (isn’t so direct if you wanna know), and tested it in front of me!

There was a spark gap of about 3cm between a wire the guy was holding and the transformer, and the electricity just flew through the air to the wire! That’s 15000V for you!

She also said I needed High Tension wires which were very expensive. I asked where I could buy them, and she said that normal hardware shops do not sell them. Instead, she simply gave me 1m of the wire for free. Did I mention how nice she was?

More interestingly, one of the workers came and asked me about why I needed the transformer for. I said school project, and since I was wearing the BP school uniform, he spoke to me in chinese something like “You’re from BPGHS? BPGHS have these kind of projects? I thought you were from some brand-name school…”

Um.

And then, he went on to say that he had friends from BP and friends from brand-name schools. He said those from BP were always involved in fighting.

I said I graduated already, and told him I’ll be going to ACJC. And he was like, once again in Chinese, “Not bad, can make it to JC… Good thing you can have university education…” Well, obviously he doesn’t, so… uhh…

Pity.

Also, he asked me how I can find such an ulu place that deals with Neon Signs. I told him that I checked the yellow pages. This time, the stupidest reply came: “Our place is listed in the yellow pages?!”. LOL. The ladies also wondered how I managed to find their extremely, extremely secluded office, which was so TOTALLY LOL.

They charged me $45 for the transformer, although the boss said $50. She said she’s very supportive of students, so she’ll give me a discount. Damn nice lor.

They kept asking me how I going to bring back the transformer, and I said I can carry. They doubted me. But for a good reason.

After I paid for everything, I left the place with the 13 kg transformer in a bag. I walked to the lift, went down, and out of the building. Covered about 50m, and I gave up. The transformer was deceivingly small. It was rather cute actually, and about 1.5 times the size of a computer power supply which is very light. 13 kg of metal, into a small box, helluva time to carry. I asked around for the bus to board for the nearest MRT station, and a woman said she was heading there as well, so I’ll just have to follow her. Even in the bus, putting the transformer on my thighs killed them. 13 kg, GRAH.

And now my arms are sore, my legs are tired and whole body is aching.

Which concludes this ridiculously long story.

Comments(0) 1:52 AM 3 March 2007

Um, TODAY Part #2

Posted by HELiX

AHAHAHA new entry for the ridiculous fun of it. And to hit entry #200.

Okay, continuing from school… I had… I had- YES! BOWLING!

Kok was bowling with some of his classmates and he invited me over. Gotta love the game! <3

And then, and then, we bowled. Duh.

OKAY AND THEN I BROKE MY PERSONAL BEST TO GET 202 FOR A GAME! ZOMG LIEK, WHOA.

Oh and um, Hi Clement!

I’m not gonna brag about getting 202 pinfalls this time cos Clement’s personal best was 208. H4XX0R LOR.

But yeah-hoo! 202 Pinfalls!

This is my secret:

Made the day all-the-more funner and awesomer.

Comments(0) 1:51 AM 3 March 2007

Um, TODAY

Posted by HELiX

What can I say? I mean, TODAY was teh SO AWESOME (compared to other days)!!!111oneone

Not quite, but the point of it is to give this entry a catchy beginning. But generally, today was fun. Period.

I don’t know where to start, but I spent 3 hours in school playing Max Payne 2 (again, after completing it years and years ago) on the laptop because Wei Rong hasn’t completed it yet =/ And also we had a long seriously long break.

So yup, how often does school seem fantastic? Well actually, NEVER! But breaks are part of schooling and it’s the little things like this that makes school the least puny bit fantastic.

And this, amazingly amazing, is all I have to say about school which ended at 1pm. Sweet.

No actually, I wanted to end here so that I can create another entry.

Comments(0) 1:50 AM 3 March 2007

#191 Entry!

Posted by HELiX

Almost 200 entries, so I’m gonna SPAM entries to reach that figure.

No worries, they’ll still be decently good ones.

…

Except this.

Comments(0) 11:16 PM 3 March 2007