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Tesla Hair Pin experiment -help

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JamesH

Thu Aug 18 2011, 04:44PM

Registered Member #579 Joined: Mon Mar 12 2007, 09:45AM
Location: Burntwood, Staffs, England
Posts: 46

I am trying to replicate the TESLA HAIR PIN experiment .I have the spark gap sparking fiercely - showing the capacitors are working OK , but I can not get the "standing wave " phenomenon to work on the legs
VIZ. I cannot get high and low voltage nodes , detected by sliding a low voltage lamp up and down the legs
Also, in you tube videos, the demonstrators seem to be able to slide the connector up and down the legs with out sustaining a shock where as I do get a shock off the legs
The legs are 1m of 8mm copper tube , the caps are 200pF at 40Kv doorknobs
The spark gap is tungsen rod and the transformer 6.7kV( 240v AC)
Do I need to tune it in some way ?
Any experienced advice would be gratfully received

Mattski

Fri Aug 19 2011, 04:41AM

Registered Member #1792 Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527

This appears to be something seized upon as an apparatus for harvesting "radiant energy" by Tesla fanboys... nevertheless what you have there is a resonator.

Without trying to run some numbers or experiments I'm not sure if it acts like a lumped element LC resonator or a distributed resonator. A distributed resonator is needed for standing waves to be visible. When I watched

it looked like the bulb got dimmer towards the top and brighter towards the base, which does not mean that there is a standing wave. To see evidence of a standing wave there needs to be an inflection point, i.e. a minimum point which as the bulb is moved in either direction away from it the bulb brightness increases, or the opposite for a maximum. If the rod of wire is acting like a single inductor more so than a two wire transmission line then the bulb is simply spanning a greater inductance when it is near the base, and since the (AC) voltage across an inductance is proportional to the current (which is constant throughout the inductor) and the inductance, then the voltage between the two rods is going to be higher near the base then the top.

So anyway, do you at least see an increase in brightness towards the bottom, and a decrease at the top? Or are you seeing no variation? You are using 1M rod length, what is the separation?

JamesH

Fri Aug 19 2011, 06:49AM

Registered Member #579 Joined: Mon Mar 12 2007, 09:45AM
Location: Burntwood, Staffs, England
Posts: 46

Thanks for the information. OK the term standing wave was sed loosely .Asyou ave watched the video you get the idea. I was more interested in the fact he does not get a shock as he moves the live connectors or handles the legs - my set up is certainly live at 6kV - ouch
There is NO variation in brightness and a 12V lamp is only half normal brightness. The rods are 39 inches tall and 5 inches apart

Mattski

Fri Aug 19 2011, 02:49PM

Registered Member #1792 Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527

My best guess as to why he does not get shocked is that his body is a much higher impedance compared to the rest of the circuit, so not much current will flow through him. The human body can have a widely varying impedance, mostly dependent on the moisture on your skin and how tightly you grip the conductor. Also is the secondary of your transformer ground isolated? Most NST's by default are not, and this might increase shock potential as your body can have a path to ground. It's still a good idea to only handle a live high voltage circuit with push rods even if you think you're safe.

Maybe you could try bulbs of different impedances, I'm guessing you want a bulb with a somewhat higher resistance so that it does not itself act like the shorting rod.

Forty

Fri Aug 19 2011, 03:29PM

Registered Member #3888 Joined: Sun May 15 2011, 09:50PM
Location: Erie, PA
Posts: 649

as matt said, I don't think it's a good idea to grab the conductors with that kind of voltage on it, especially when the setup isn't functioning properly yet lol.
is the spark gap supposed to automatically tune itself to resonance or do the conductors have to be cut to the proper length? the setup in the vid looked to be spaced further than 5 inches apart, so i'm just wondering if that matters.

Mattski

Sat Aug 20 2011, 03:31AM

Registered Member #1792 Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527

Forty wrote ...

is the spark gap supposed to automatically tune itself to resonance or do the conductors have to be cut to the proper length? the setup in the vid looked to be spaced further than 5 inches apart, so i'm just wondering if that matters.

The system should actually already be at resonance. The circuit is pretty much the same as a tesla coil primary tank circuit but with an elongated single turn coil instead of a pancake multi-turn one. There is no secondary which needs to be set to the same frequency as the primary, so whatever resonant frequency the primary happens to have it will oscillate at when the spark gap breaks.

JamesH

Sat Aug 20 2011, 08:06AM

Registered Member #579 Joined: Mon Mar 12 2007, 09:45AM
Location: Burntwood, Staffs, England
Posts: 46

Thanks for all your replies
Yes! I do know about HV so I do know about electric shocks having built several Tesla coils and other HV apparatus.. fly backs Ignition cois -all over driven.
I have tried different: lamps; position of the shunt; caps ( 940pF and 2000pF); spark gap width . All to no avail
I hoped some one who had successfully built the aparatus and experimented with it would answer my request fo help
One more day and I will give up despite having paid a fortun:for the "proper " capacitors from the USA

Mattski

Sat Aug 20 2011, 05:48PM

Registered Member #1792 Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527

In your diagram I see there is a yellow thing just above the capacitors, is that another lamp? What happens if you take that out? If it's low enough impedance compared to the rest of the inductor then it could be taking much of the current from the tank which would lead to more constant voltage on the rails above it.

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