Tungsten Contacts for Spark Gaps

[jeff_behary]

Hello All,

I am trying to resurrect a dead business of making Tungsten Contacts. These were standard for Tesla experiments, and we have spark gaps more than 100 years old that use them and still function beautifully.



Unfortunately, there are no manufacturers here in the USA that actually produce the contacts in small quantities for hobbiests. I am attempting to change that.



For contacts alone, priced in pairs (2 each), brazed to Stainless Steel machine screws, I have the following prices so far.

.1875" diameter - $18.75 / pr
.2500" diameter - $25.00 / pr
.3125" diameter - $31.25 / pr
.5000" diameter - $50.00 / pr
.7500" diameter - $75.00 / pr
1.250" diameter - $125.00 / pr

The contact faces are pure tungsten 1/16" thick. Many early gaps were
only half as thick. They also work well for induction coils and interrupters.

Quantities will be limited.
Please email jeff_behary@hotmail.com for more details.

Custom machined heat sinks and complete spark gaps are also available.

Jeff Behary

[thedude]

nice

Very nice Jeff. I've been watching all of your videos and have recently been fretting over my spark gap delemas. I'm currently using a rotary gap that has been over stressing my caps (MMC bank) but i think i may have found a better balanced frequency and capacitance that works with out too much trouble now. (think i might have burnt a couple out already , lots left though)
I'm just starting out with "Coiling" and have a thread with my first real Tesla coil in a youtube vid here
Its not all that impressive, however it was one of my first trial runs. I have since tuned it much better and have been seeing multiple discharge effects taking place. Not too bad for 4KV anyway i guess.
I just printed out Tesla's pancake coil patent and i have plans to replicate a few of them for my self. I have a neon sign transformer 12KV on order as well.
I guess what i'm saying is YES i could really use some of your tungsten spark gap contacts. I will be emailing you, most likely on the 12th of this month to arrange payment and shipping if all is well and they are available.
Sorry for my long rant. Was wondering? Do you worry about your dog taking a snap at the discharge current? I can't seem to keep my cat,"Trip",away. He desperately wants to be around to watch the air coil transformer in action. :P I worry that with all that fur that he would be prime for a short.

[jeff_behary]

4kV is good!

Very nice Jeff. I've been watching all of your videos and have recently been fretting over my spark gap delemas. I'm currently using a rotary gap that has been over stressing my caps (MMC bank) but i think i may have found a better balanced frequency and capacitance that works with out too much trouble now. (think i might have burnt a couple out already , lots left though)
I'm just starting out with "Coiling" and have a thread with my first real Tesla coil in a youtube vid here
Its not all that impressive, however it was one of my first trial runs. I have since tuned it much better and have been seeing multiple discharge effects taking place. Not too bad for 4KV anyway i guess.
I just printed out Tesla's pancake coil patent and i have plans to replicate a few of them for my self. I have a neon sign transformer 12KV on order as well.
I guess what i'm saying is YES i could really use some of your tungsten spark gap contacts. I will be emailing you, most likely on the 12th of this month to arrange payment and shipping if all is well and they are available.
Sorry for my long rant. Was wondering? Do you worry about your dog taking a snap at the discharge current? I can't seem to keep my cat,"Trip",away. He desperately wants to be around to watch the air coil transformer in action. :P I worry that with all that fur that he would be prime for a short.

A lot can be done with tungsten and 4kV from 2 MOTS!
I made a fairly mean coil that uses $$$ 3/4" tungsten - a 2-series gap.
The gap gets hot, but so do the sparks!




Tungsten is ready when you are!

[amigo]

Hey Jeff

First, a belated welcome to our forum and, thanks for the very fine work you have been doing so far with your experiments and the material you bring up on your website.

I have a question for you about spark gaps:

What's your take on the flat vs. curved surfaces of the gaps, as I see all your machined ones are flat?

Somehow I am under the impression that the curved (spherical or hemi-) gaps behave better than the flat ones. Maybe I read that somewhere as well, but from limited testing I have done I somehow lean towards curved ones.

This also brings me to a tapered (needle) point gaps as well, are they something worth exploring?

[thedude]

love your images.

I had noticed that when my rotary gap stopped spinning once, leaving a double gap in series that went into full on hard resonance, that was when i definately saw my best discharge off of the topload. Problem with my set up is that i'm still using tiny welding rods that work ok while in high rotation. When static, they burnt up like match heads in about 6 seconds! :P Still, it was the best i've seen my TC run yet.

$75 for 3/4" pr sounds solid to me. I've seen vacuum quenched systems, but would like to keep it simple as possible, perhaps a couple bedini SSG fans cooling a heat sink in the mid point of the double series gap(edit - I guess by simple i mean fewer external hookups). I like your design by the way.

Monday the 14th will be my payment now. Do you do paypal?

Also in the market for a good topload. Mine is homemade and really looks like garbage. :P Definately planning on really cleaning things up once i have a solid setup. Still very diagnostic at this point. What is your prefered shape for a topload? Sphere or toroid?

Sorry for all the questions by the way. Feel free to address Amigo's queries first.

[phi1.62]

Jeff, have you considered manufacturing magnetically quenched spark gaps like the ones Tesla specified in his London lecture?

[jeff_behary]

Gaps...

Sorry for the delay, real life is taking over.

Some answers:

I have found flat gaps work better, but have never seen spherical tungsten (which might change my mind). The closest I've seen is spherical tungsten carbide, and I've had bad luck with tungsten carbide.

Many times people think there is "one gap, and only one gap" but really I've found it depends a lot on the coil, and the whole picture. My reasoning is that if a Tesla Coil only has a few components, then they are all important and effect each other in how everything operates on a whole...

I think for induction coils and very high voltage (and low current) tanks the gap is less cricitical than with low tensions and high currents - and a simple spark gap even brass balls work okay. Early wireless gaps sometimes used zinc before tungsten became the standard. Tungsten is REALLY good. I don't think there is better material. I've tried a few materials experimentally - copper, brass, iron, stainless steel, aluminum, titanium, monel, platinum, silver, tantalum, carbon, graphite, mercury - and always end up using Tungsten!

That high melting point really makes a difference. All metals are expensive now, and I prefer tungsten because I know its longevity with our antique coils.

I tend to prefer static gaps to rotary, just for simplicity. For high power levels, rotary gaps are definately great. But for a few thousand watts, I like the option of not having a motor involved...But it isn't to say you cannot get excellent results even at low power levels with a rotary. I did some experimental work at 10,000 BPS with a stainless steel rotary gap.

I have a tungsten target from a rotating anode X-Ray tube I will eventually make a super-high power gap with. It is around 3" in diameter, 75mm or so. At 3600 RPM, and some massive stationary contact, I might try some insane power levels - 1000 or 2000mA or more of current.

With magnetic quenching, I think the modern magnets will supercede anything done in the past with electromagnets. I built some electromagnet quenched gaps in the spirit of the Poulsen Arc gap earlier in the year (and on the site), and found the electromagnets simply weren't powerful enough no matter what voltage I used. I could get similar results without them in the circuit. But with rare earths/etc. I think if someone invests in something powerful they will see a difference. But also, as Tesla said - the difference isn't so great unless the other parameters of the circuit are correct. I agree here. It is interesting when a system is very in tune even a horrible gap will do wonders, and likewise, a badly tuned system can have the best spark gap imaginable and not give good results!

A big factor I think is to match the charging circuit with the cap and coil used. High powers and high currents do best with low frequencies. Also certain cap ranges work best with various transformers/current ratings.

I do have a 2 foot tall electromagnet with approx. 7" diameter core missing I would like to experiment with. But I need a core. That's a big core to find accidentally, and too expensive to build on purpose. I am hoping to start with a 6" SCH 40 pipe (steel) if I can find one!

Also, for interest - the 6" diameter water-cooled copper plate spark gap that Kinraide used (that I've reproduced on the site) works well for that coil, but is quite difficult to use with other coils. That gap was later used in wireless telegraphy by Wein, Von Lepel, Telefunken, etc...

Some GREAT designs for spark gaps can be found in Wireless Telegraphy books. They normally give a better description of gaps. Classic authors include Bucher, Zenneck, etc...well worth a trip to Google Books. Wireless Telegraphs were Tesla Coils...just ask Marconi!

Jeff

[jeff_behary]

Self-Cooling Spark Gaps

We've updated our Tungsten Contact page to include
a page on self-cooling Spark Gaps!

For Sale: Tungsten Contacts and Self-Cooled Spark Gaps for Tesla Coils http

The Turn Of The Century Electrotherapy Museum Tesla Library









Let me know if anyone needs anything made!
Jeff