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Re: [TCML] static gap singing coil hybrid.
If you need a beefy resistor...
Try stacking squares of carbon and just tapping the ends in a vice. graphite might work as well
You get a variable resistor where a fixed metal plate and a movable one serve as the terminals ; the resistance value is reduced by applying pressure to the movable plate.
I have no idea what the effective resistance range that can be achieved would be, but I know that these guys can handle hundreds of amps no problem
a lot lighter than a salt water resistor as well =)
Thanks,
John "Jay" Howson IV
"Why thank you, I will be happy to take those electrons off you hands."
----- Original Message -----
From: "Scott Bogard" <sdbogard@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, January 26, 2011 10:14:27 PM
Subject: Re: [TCML] static gap singing coil hybrid.
Oh yes, that makes sense... If I get impatient I'll probably just make
a resistor out of a bucket of salt water and some metal plates, very
inefficient and short lived but I imagine it will prevent inrush to the
gap and still allow the tank cap to charge. It will be some time before
I build a prototype as I have no idea how to interface with midi, though
I suppose I could rig a 555 timer with about 4% duty cycle at 30Hz-5khz
to trigger another driving a flyback at 100 kHz to be my trigger, that
way I can get at least steady sound, pitch adjustable with a
potentiometer as proof of concept, and not worry about midi until later.
Scott Bogard.
On 1/25/2011 9:33 PM, Phillip Slawinski wrote:
> Scott,
>
> The MOTs will probably work. Also the charging inductor serves the purpose
> of limiting the current from the filter capacitors when the spark gap is
> triggered. Remove the inductor, and you end up dumping the the filter
> capacitors across the spark gap when it's triggered.
>
> -Phillip
>
> On Tue, Jan 25, 2011 at 17:55, Scott Bogard<sdbogard@xxxxxxxxx> wrote:
>
>> Phillip,
>> I was planning on eventually building a DC coil eventually anyway,
>> and I have enough microwave oven capacitors and diodes that I could build a
>> MOT based level shifter with all the current I can handle, not sure if that
>> would cut it or if I would need a resonate charging inductor, which could be
>> made with more MOTs in theory. Since it is triggered it shouldn't need an
>> especially high voltage I suppose, so 4kV was where I was aiming. The
>> biggest hurtle I see is cooling, having that arc that close to glass for
>> prolonged periods will be tricky, but maybe if I run cold air or oil or even
>> water through the tube, its life expectancy should be similar to glass jar
>> capacitors I'd imagine, even if I only get 15 minutes out of it glass tubing
>> is a lot cheaper than IGBT's, and is easy to replace...
>>
>> Scott.
>>
>>
>> On 1/25/2011 1:13 PM, Phillip Slawinski wrote:
>>
>>> Scott,
>>>
>>> While this looks okay in theory, there would be some limitations. The
>>> main
>>> limitation would be that this could only work with a DC charging system.
>>> This adds complexity to the project, because you must then locate large HV
>>> filter caps, diodes, and a properly designed charging reactor. Aside from
>>> those issues, I don't see any fundamental reasons why it can't be done.
>>> If
>>> you do this please share your results.
>>>
>>> -Phillip
>>>
>>> On Tue, Jan 25, 2011 at 11:44, Scott Bogard<sdbogard@xxxxxxxxx> wrote:
>>>
>>> Greetings all,
>>>> So I was looking at this web page today at work for no particular
>>>> reason...
>>>> http://www.glacialwanderer.com/hobbyrobotics/
>>>> If I am understanding this correctly, he essentially built a spark gap
>>>> triggered by the corona around the inner glass tube from his trigger
>>>> coil. If that is correct would it be terribly easy (if extremely
>>>> inefficient) to make a singing coil by constructing a similar spark
>>>> gap (with better cooling for actual run times) and just trigger the
>>>> inner coil with a midi signal. This way for those of us who don't
>>>> want to tackle DRSSTC yet, can just build essentially a midi triggered
>>>> flyback, to gain familiarity with the audio interfacing without the
>>>> added complication of going strictly solid state, and the expense of
>>>> IGBTs. Has anyone tried this?
>>>>
>>>> Scott.
>>>> _______________________________________________
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