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Author Topic: less 20ns switching in a coil without transistors  (Read 4913 times)

giuseppe

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less 20ns switching in a coil without transistors
« on: February 01, 2020, 09:40:09 PM »
What type of  oscilante system  is possible to be used to create pulse signal /switching ( less 20ns) in a coil ?  old school
Without transistors or another electronic systems / NO silicon-based .

Toolofcortex

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Re: less 20ns switching in a coil without transistors
« Reply #1 on: February 01, 2020, 09:41:37 PM »
Tube and mechanical rotationnal spark gap.

??


Raycathode

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Re: less 20ns switching in a coil without transistors
« Reply #2 on: February 06, 2020, 10:48:35 PM »
Why make it hard, a commutator and stator and carbon brushes just collect the narrow pulses,

Toolofcortex

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Re: less 20ns switching in a coil without transistors
« Reply #3 on: February 06, 2020, 11:00:34 PM »
Its inefficient as you need a mechanical source.

How much energy you need to charhe the capacitor of a MOSFET and let flow?

what loss penalty? Even with thermal loss of MOSFET.


Raycathode

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Re: less 20ns switching in a coil without transistors
« Reply #4 on: February 07, 2020, 03:40:42 AM »
Its inefficient as you need a mechanical source.

How much energy you need to charhe the capacitor of a MOSFET and let flow?

what loss penalty? Even with thermal loss of MOSFET.
Make up your mind you want mechanical or semiconductor ? if you use a PNP and an NPN you can trigger it on the knee and instantly discharge the cap, are you racing electrons rise time here ?

Toolofcortex

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Re: less 20ns switching in a coil without transistors
« Reply #5 on: February 07, 2020, 05:33:42 AM »
You will not get nS pulses.

The contact time will be larger than that.

It will be in the uS.

It’s also less accurate and will degrade.

It was used back then when there was no alternative.

Raycathode

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Re: less 20ns switching in a coil without transistors
« Reply #6 on: February 07, 2020, 07:40:04 AM »
is all you appear to need to be able to do is charge an HV cap over a short time and then 'bang' dump and discharge that energy into a coil that's what they say and it works in TV sets so it's just that discharge time.

Toolofcortex

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Re: less 20ns switching in a coil without transistors
« Reply #7 on: February 07, 2020, 04:40:54 PM »
Ok I see what you mean...

Just charge the line let it flow at the peak points where air onizes and turns conductive.

Yeah that would work too.

It would not be a precise and accurate pulse all the time tho.




Raycathode

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Re: less 20ns switching in a coil without transistors
« Reply #8 on: March 10, 2020, 02:45:01 PM »
This thread looks Abandoned However this might be of interest.

Here is one way using Bucking coils the pulse width is some where around 520 nano-secs
it uses enhancement fet’s and driven by a constant current around 3.5 volts max with the type of fets I have.
Other fets will behave differently 20N50's mounted on a heat sink which runs cold the bias is 56R shunted with
a 47pf on each gate coil, current is 1.307Amps at 3.25 volts.
There is a scope shot too, the LEDs are 1.25W consumed is 4.5W that isn’t OU it's a loss'  ::)

Raymondo
« Last Edit: March 10, 2020, 04:47:57 PM by Raycathode »