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 Post subject: Re: understanding schematics
PostPosted: Mon Feb 04, 2013 3:01 am 
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mbrownn wrote:
There are many ways to do it. The advantage to relay switching is the abruptness of the switch, placing a transistor in the circuit does tend to reduce the effect a little due to internal resistance and a more rounded transition from on to off etc. Its not that transistors cant do the frequency, in fact they are far superior, its that there is a more rounded transition.

In low power devices we need all the help we can get so I tend to like mechanical switching. As the supply voltage increases the arc itself starts to round off the switching so our advantage isn't much
Anyone ever compare the abruptness ?

What I ask before is if using capacitor to reduce spark is the correct way?

I would not consider relay to be a low power device. The relay itself need at least 150mA, some require as high as 500mA. The switching speed is a problem too. I wonder how tesla achieve 1GHz mechanical switching megawatt of current.


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 Post subject: Re: understanding schematics
PostPosted: Mon Feb 04, 2013 7:18 am 
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That's so awesome that we can't even come close to figuring out over a hundred years later things that were child's play to that guy. If he were around now, we'd have IronMan suits, teleporters, and time machines. :D

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 Post subject: Re: understanding schematics
PostPosted: Tue Feb 05, 2013 2:34 am 
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I think a capacitor is not the Ideal way, Tesla used magnetic quenching amongst other techniques. Most relays I have used ran between 80 and 200mA but the output was very good. When you slave an ignition coil to it the current is much higher as is the output. I never actually did efficiency tests but I know it was well above 80% and possibly above 90%

I once used a solenoid off a starter motor for a car and a welding transformer as the coil. the power was huge, I would say lethal but the efficiency was low and the frequency in the 1 to 5 hz range. Bright green arcing on the contacts. I achieved up to 600Hz with an automotive relay. Tesla often used rotary spark gaps where high frequency could be obtained, with low voltage that would be a commutator. Its enough to say that Tesla was a phenomenon as no one these days can get close to what he did.

On the abruptness you need to look at the transition on the scope where the trace goes from flat to vertical, Its those rounded curves on the transition that we need to reduce.

Superdude, I think you are right.


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 Post subject: Re: understanding schematics
PostPosted: Wed Feb 06, 2013 1:26 am 
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I heard that Tesla use mercury as switch. I have mercury switch, but I hesitate to use it to switch for fear of exploding it.


I think the spark is what reduce the mechanical switch abruptness. Capacitor reduce the power and the abruptness.

I usually compare relay and transistor with diesel compare to gasoline engine. High torque and low rpm vs low torque and high rpm. Transistor have more horsepower because of its speed.

charging a 12V 7Ah battery, a 250mA transistor charger will be much faster than a 250mA relay charger. 8 hours vs few days.


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 Post subject: Re: understanding schematics
PostPosted: Wed Feb 06, 2013 11:26 pm 
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yes, he did, but I am not sure it was his final solution'

Correct the arcing is what limits the abruptness of mechanical switching.

I agree with your analogy but it does not have to be that way. The problem with low power systems is the mechanical power required for the switching is too great but as the size and power increases then the gap narrows. The size Tesla was using, the amount of power used by the switching was insignificant when compared to the energy produced.


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 Post subject: Re: understanding schematics
PostPosted: Thu Feb 07, 2013 2:05 am 
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mbrownn wrote:
yes, he did, but I am not sure it was his final solution'

Correct the arcing is what limits the abruptness of mechanical switching.

I agree with your analogy but it does not have to be that way. The problem with low power systems is the mechanical power required for the switching is too great but as the size and power increases then the gap narrows. The size Tesla was using, the amount of power used by the switching was insignificant when compared to the energy produced.
But did Tesla use spark to obtain free energy?

I heard he purchase tube? What the tubes for because I don't think Tesla need to use tube to make spark?


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 Post subject: Re: understanding schematics
PostPosted: Thu Feb 07, 2013 12:08 pm 
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i finaly got everything working, with egnition coil in paralel with the relay. I used 2 400v 1.2uf in series on bothe sides, now i got almost no sparking at al. Now i wonder if there is a way to place a potentiometer somewhere on relay, like they do with the transistor models, to fine tune it? I've tried a lot of different lamps, but i can't get non of theme to shine in full brightness, any suggestions? Thank you.


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 Post subject: Re: understanding schematics
PostPosted: Thu Feb 07, 2013 10:35 pm 
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sucahyo wrote:
mbrownn wrote:
yes, he did, but I am not sure it was his final solution'

Correct the arcing is what limits the abruptness of mechanical switching.

I agree with your analogy but it does not have to be that way. The problem with low power systems is the mechanical power required for the switching is too great but as the size and power increases then the gap narrows. The size Tesla was using, the amount of power used by the switching was insignificant when compared to the energy produced.
But did Tesla use spark to obtain free energy?

I heard he purchase tube? What the tubes for because I don't think Tesla need to use tube to make spark?


I believe Tesla Invented many tubes from diodes to pentodes, they were even named after him.

Quote:
i finaly got everything working, with egnition coil in paralel with the relay. I used 2 400v 1.2uf in series on bothe sides, now i got almost no sparking at al. Now i wonder if there is a way to place a potentiometer somewhere on relay, like they do with the transistor models, to fine tune it? I've tried a lot of different lamps, but i can't get non of theme to shine in full brightness, any suggestions? Thank you.


No pot is required, any resistance is a loss. Use heavy duty wire (low resistance) and try different ways of lighting the tube ie single wire etc. To get the tube to light brighter you would need to increase frequency, which is difficult with a relay, or increase input voltage.

You will find that you don't need to connect the wires to the terminals on the tube, you can just wrap the wire around the tube and it will work.


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 Post subject: Re: understanding schematics
PostPosted: Fri Feb 08, 2013 2:23 am 
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There are two ways to use the flourencent bulb. I think not utilizing the filament is what suitable for relay based circuit. I would use both for transistor version. I use the filament with the low voltage output (from the main coil), and use the high voltage output between the electrode (from the HV secondary coil).

mbrownn wrote:
I believe Tesla Invented many tubes from diodes to pentodes, they were even named after him.
Ok. thanks.


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