Discharge a huge voltage

L

lerameur

Guest
hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?

Thanks
 
On Wed, 3 Mar 2010 17:16:23 -0800 (PST), lerameur <lerameur@yahoo.com>
wrote:

hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?
Click to expand...
---
At the very least, yes.

But...

There will be inductance in the circuit, so depending on how fast you
turn off the current into the load,

L dI
E = ------
dt

might eat your lunch.

JF
 
lerameur wrote:
hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?

Thanks
Always apply a safety factor, I would use 800 and 30.
Click to expand...
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.
 
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry
<burrynulnulfour@ppllaanneett.nnll> wrote:

lerameur wrote:
hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?

Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.
Click to expand...
If he is saying

" (900v max capacity)"
Click to expand...
Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?
 
Hammy wrote:
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry
burrynulnulfour@ppllaanneett.nnll> wrote:

lerameur wrote:
hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?

Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.

If he is saying

" (900v max capacity)"

Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?
He knows best, just apply some safety factor over the highest
Click to expand...
expected values.
 
lerameur wrote:
On Mar 3, 9:20 pm, Hammy <s...@spam.com> wrote:
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry



burrynulnulf...@ppllaanneett.nnll> wrote:
lerameur wrote:
hello,
I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?
Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.
If he is saying

" (900v max capacity)"
Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?

The capacitor can take up to 900v, but I am only charging it to 600v..
I thought maybe if I can get some transistors in parallel to drain
the current, but using transistor rated below 600v. But I do not think
it will work.

It will work ONCE. After that you have a permanent short.
Click to expand...
 
On Mar 3, 9:20 pm, Hammy <s...@spam.com> wrote:
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry



burrynulnulf...@ppllaanneett.nnll> wrote:
lerameur wrote:
hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval.  I have 30 ohm
resistance, without so from my calculation I should have 20 amp  max..
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?

Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.

If he is saying

" (900v max capacity)"

Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?
Click to expand...
The capacitor can take up to 900v, but I am only charging it to 600v..
I thought maybe if I can get some transistors in parallel to drain
the current, but using transistor rated below 600v. But I do not think
it will work.
 
On Wed, 3 Mar 2010 17:16:23 -0800 (PST), lerameur <lerameur@yahoo.com>
wrote:

hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?

Thanks
Click to expand...
900 uF and 30 ohms makes a 27 millisecond time constant. So after 10
milliseconds, you'll still have 400 volts or so.

When you say discharge at "0.01 seconds interval" do you mean
discharge it *every* 10 milliseconds? What are you trying to do?

Yes, you need a transistor or mosfet rated for 600 (or 900?) volts and
20 amps peak current.

The resistor will have to absorb a lot of energy.

John
 
On Mar 3, 10:53 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Wed, 3 Mar 2010 17:16:23 -0800 (PST), lerameur <leram...@yahoo.com
wrote:

hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval.  I have 30 ohm
resistance, without so from my calculation I should have 20 amp  max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?

Thanks

900 uF and 30 ohms makes a 27 millisecond time constant. So after 10
milliseconds, you'll still have 400 volts or so.

When you say discharge at "0.01 seconds interval" do you mean
discharge it *every* 10 milliseconds? What are you trying to do?

Yes, you need a transistor or mosfet rated for 600 (or 900?) volts and
20 amps peak current.

The resistor will have to absorb a lot of energy.

John
Click to expand...
This is the first step for ultimatly a tesla coil. In the first I
would like to control the capacitor discharge. The circuit above I
will create a gap for the spark. If I do not put the transistor then I
cannot control the discharge and everytime a spark will occur, it will
empty my capacitor. And to do this, it will take almost .5 seconds,
which is too long.

JP
 
"lerameur" <lerameur@yahoo.com> wrote in message
news:b7622678-8abe-4070-8567-38773d727ce6@y17g2000yqd.googlegroups.com...
hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?

Thanks
Click to expand...
As others have said, you need a switch FET, parallel FETS, IGBTS or
whatever more robust than 20A and 600 volts. Probably at least 30 A and 800
volts.

But, the time constant of 30 ohms and 900uF = 0.027 seconds. So, it's not
quite clear what you expect to do every 0.01 sec, 10msec. In that time the
cap will not be recharged or discharged hardly at all through a 30 ohm
resistance.

Secondly if you are trying to make a Tesla coil circuit, you barking up the
wrong tree. Tesla coil primaries require very high voltages, at least 10kV
to be effective. The capacitor is in resonance with the primary inductance
at or above 100kHz. The secondary is also in resonance at the same frequency
with it's inductance and self capacitance. The primary capacitors are in the
range of 100's of pico farads to several nano farads depending on the
primary inductance they are intended to resonate with. The capacitor voltage
has to be way in excess of the driving voltage typically 10kV to 20kV. Also
the capacitor must be able to withstand high RF currents.

You mentioned a spark gap?? There is no way 600 volts will bridge a gap.
That voltage is way too low. You have to get to several kV before and air
gap is effective.

Good luck with your adventure.
 
lerameur wrote:
On Mar 3, 9:20 pm, Hammy <s...@spam.com> wrote:
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry



burrynulnulf...@ppllaanneett.nnll> wrote:
lerameur wrote:
hello,
I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?
Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.
If he is saying

" (900v max capacity)"
Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?

The capacitor can take up to 900v, but I am only charging it to 600v..
I thought maybe if I can get some transistors in parallel to drain
the current, but using transistor rated below 600v. But I do not think
it will work.

Certainly not in parallel -- a parallel connection sees the full voltage
Click to expand...
across each device.

In theory you could connect transistors in series, with appropriate gate
or base drivers. But it'd be a lot cheaper to just get a 900V transistor.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
 
lerameur wrote:
hello,

I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?
Click to expand...
Were you discharging down to nothing I'd suggest an SCR (or stack
thereof). But you're not...

You need to get a transistor that's rated for _more_ than 600V -- the
voltage rating on any device is "don't ever exceed this, even once, or
it'll die, you'll die, men, women and children will die, aughhhhhhhh!".
Different companies and industries treat this absolute maximum rating
with different attitudes -- electrolytic capacitors are generally rated
much closer to the edge than semiconductors, for example.

I'd use a transistor that's rated for at least 800 or 900V, and if that
900uF cap is electrolytic I'd consider finding one that's good to 1200V.

The current ratings that they put in big print on FET data sheets is
based on a well heat-sunk transistor that's operating continuously at
room temperature. You really need to do the thermal analysis for your
particular situation to make sure that your power devices aren't going
to go 'poof!'. When you're done you may find that you can get by with
one rated at 20A (or less, depending on the surge or instantaneous
current rating), or you may find that you need more.

Post a copy of your circuit someplace and folks will critique it for you.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
 
In article <OdOdnTwYH-NUeRLWnZ2dnUVZ_vqdnZ2d@web-ster.com>,
tim@seemywebsite.now says...
lerameur wrote:
On Mar 3, 9:20 pm, Hammy <s...@spam.com> wrote:
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry



burrynulnulf...@ppllaanneett.nnll> wrote:
lerameur wrote:
hello,
I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?
Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.
If he is saying

" (900v max capacity)"
Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?

The capacitor can take up to 900v, but I am only charging it to 600v..
I thought maybe if I can get some transistors in parallel to drain
the current, but using transistor rated below 600v. But I do not think
it will work.

Certainly not in parallel -- a parallel connection sees the full voltage
across each device.

In theory you could connect transistors in series, with appropriate gate
or base drivers. But it'd be a lot cheaper to just get a 900V transistor.


What about a big assed 'puck' style SCR / thyristor?
Click to expand...
I don't know about how fast you can trigger the things, but don't they
use them for big motor control apps?
I know you can get them with hold off voltages in the 1000V+ range and
dump hundreds of amps through them. Might get a bit hot, but what about
the heat from the cap ESR???
 
WangoTango wrote:
In article <OdOdnTwYH-NUeRLWnZ2dnUVZ_vqdnZ2d@web-ster.com>,
tim@seemywebsite.now says...
lerameur wrote:
On Mar 3, 9:20 pm, Hammy <s...@spam.com> wrote:
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry



burrynulnulf...@ppllaanneett.nnll> wrote:
lerameur wrote:
hello,
I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?
Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.
If he is saying

" (900v max capacity)"
Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?
The capacitor can take up to 900v, but I am only charging it to 600v..
I thought maybe if I can get some transistors in parallel to drain
the current, but using transistor rated below 600v. But I do not think
it will work.

Certainly not in parallel -- a parallel connection sees the full voltage
across each device.

In theory you could connect transistors in series, with appropriate gate
or base drivers. But it'd be a lot cheaper to just get a 900V transistor.


What about a big assed 'puck' style SCR / thyristor?
I don't know about how fast you can trigger the things, but don't they
use them for big motor control apps?
I know you can get them with hold off voltages in the 1000V+ range and
dump hundreds of amps through them. Might get a bit hot, but what about
the heat from the cap ESR???
Click to expand...
Turn-off becomes an issue. I know that there are ways to turn off an
SCR on a DC supply, but it's some wacky thing involving an auxiliary
inductor that snaps the current off briefly so the SCR can turn off --
it all looks pretty smoky to me.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
 
lerameur wrote:
On 4 mar, 12:35, WangoTango <Asgar...@mindspring.com> wrote:
In article <OdOdnTwYH-NUeRLWnZ2dnUVZ_vqdn...@web-ster.com>,
t...@seemywebsite.now says...



lerameur wrote:
On Mar 3, 9:20 pm, Hammy <s...@spam.com> wrote:
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry
burrynulnulf...@ppllaanneett.nnll> wrote:
lerameur wrote:
hello,
I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval. I have 30 ohm
resistance, without so from my calculation I should have 20 amp max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?
Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.
If he is saying
" (900v max capacity)"
Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?
The capacitor can take up to 900v, but I am only charging it to 600v..
I thought maybe if I can get some transistors in parallel to drain
the current, but using transistor rated below 600v. But I do not think
it will work.
Certainly not in parallel -- a parallel connection sees the full voltage
across each device.
In theory you could connect transistors in series, with appropriate gate
or base drivers. But it'd be a lot cheaper to just get a 900V transistor.
What about a big assed 'puck' style SCR / thyristor?
I don't know about how fast you can trigger the things, but don't they
use them for big motor control apps?
I know you can get them with hold off voltages in the 1000V+ range and
dump hundreds of amps through them. Might get a bit hot, but what about
the heat from the cap ESR???- Masquer le texte des messages précédents -

- Afficher le texte des messages précédents -

I do not want to discharge all the gap,
Ok Bob mentionned the time delay, I may have to reduce the resistance,
(increase the current) BUt I need a spark in the circuit.
So capacitor, resistance, spark gap and transistor.
Ok so I need several kV, lets say 3000v , but now lets say I use a 10
ohm resistance, that gives use a wapping 300 amp.
Is there such a transistor rated at 3kV and 300 amp?

That was my original idea, but when I saw outstanding figures I
decided to decrease the voltage and start low.
Click to expand...
Maybe if you share _all_ of what you _really_ want to do?

There are IGBT modules (if not individual transistors) that do over 3kV,
and if you can't find one that does 300A, you can probably gang them
together if you can figure out the current sharing.

600V would make a spark gap difficult to control, although I suppose you
could make it happen.

Just how you trigger the spark has a huge cost/precision tradeoff;
knowing how tightly you need to control the spark makes a big difference
to how you may want to drive it.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
 
On 4 mar, 12:35, WangoTango <Asgar...@mindspring.com> wrote:
In article <OdOdnTwYH-NUeRLWnZ2dnUVZ_vqdn...@web-ster.com>,
t...@seemywebsite.now says...



lerameur wrote:
On Mar 3, 9:20 pm, Hammy <s...@spam.com> wrote:
On Thu, 04 Mar 2010 03:03:26 +0100, Sjouke Burry

burrynulnulf...@ppllaanneett.nnll> wrote:
lerameur wrote:
hello,
I have a very simple circuit here, I am charging a 900uF capacitor to
600v. (900v max capacity)
I want to discharge this at 0.01seconds interval.  I have 30 ohm
resistance, without so from my calculation I should have 20 amp  max.
All this element are in series with each other, I want to add a
transistor (or mosfet) to make and break the intervals I need.
DO I need to get a 600v and a 20 amp rated transistor ?
Thanks
Always apply a safety factor, I would use 800 and 30.
Whether the 30 amp is needed depends on your duty cycle,
if the dutycycle is low, 20 and even 10 might be enough.
Just check the allowed peak current.
If he is saying

" (900v max capacity)"
Shouldnt he be useing a 1kV-1.2kV fet or IGBT with maybe a drain
clamp?

The capacitor can take up to 900v, but I am only charging it to 600v...
I thought maybe if I can get  some transistors in parallel to drain
the current, but using transistor rated below 600v. But I do not think
it will work.

Certainly not in parallel -- a parallel connection sees the full voltage
across each device.

In theory you could connect transistors in series, with appropriate gate
or base drivers.  But it'd be a lot cheaper to just get a 900V transistor.

What about a big assed 'puck' style SCR / thyristor?
I don't know about how fast you can trigger the things, but don't they
use them for big motor control apps?
I know you can get them with hold off voltages in the 1000V+ range and
dump hundreds of amps through them.  Might get a bit hot, but what about
the heat from the cap ESR???- Masquer le texte des messages précédents -

- Afficher le texte des messages précédents -
Click to expand...
I do not want to discharge all the gap,
Ok Bob mentionned the time delay, I may have to reduce the resistance,
(increase the current) BUt I need a spark in the circuit.
So capacitor, resistance, spark gap and transistor.
Ok so I need several kV, lets say 3000v , but now lets say I use a 10
ohm resistance, that gives use a wapping 300 amp.
Is there such a transistor rated at 3kV and 300 amp?

That was my original idea, but when I saw outstanding figures I
decided to decrease the voltage and start low.

JP
 
In article <K-OdneKLsMMhmQ3WnZ2dnUVZ_tCdnZ2d@web-ster.com>,
Tim Wescott <tim@seemywebsite.now> wrote:

Turn-off becomes an issue. I know that there are ways to turn off an
SCR on a DC supply, but it's some wacky thing involving an auxiliary
inductor that snaps the current off briefly so the SCR can turn off --
it all looks pretty smoky to me.
Click to expand...
It's definitely getting into the realm of tubes (mostly thyratrons)
ruling, though at high amperage the tubes are available, but do tend to
cost a few thousand dollars. At the lower amperage ranges, if you stick
to those tubes that are still commonly available they can cost a lot
less than silicon to do the same job.

On the third hand, the application becomes highly suspect as I can think
of a number of nefarious uses this might be aiming towards I wouldn't
care to help with. Not quite as blatant as the person a few months ago
that was evidently looking for help in designing a roadside bomb, but a
spark gap creates an infernal amount of RF noise...

--
Cats, coffee, chocolate...vices to live by
 
On 4 mar, 14:27, Ecnerwal
<MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote:
In article <K-OdneKLsMMhmQ3WnZ2dnUVZ_tCdn...@web-ster.com>,
 Tim Wescott <t...@seemywebsite.now> wrote:

Turn-off becomes an issue.  I know that there are ways to turn off an
SCR on a DC supply, but it's some wacky thing involving an auxiliary
inductor that snaps the current off briefly so the SCR can turn off --
it all looks pretty smoky to me.

It's definitely getting into the realm of tubes (mostly thyratrons)
ruling, though at high amperage the tubes are available, but do tend to
cost a few thousand dollars. At the lower amperage ranges, if you stick
to those tubes that are still commonly available they can cost a lot
less than silicon to do the same job.

On the third hand, the application becomes highly suspect as I can think
of a number of nefarious uses this might be aiming towards I wouldn't
care to help with. Not quite as blatant as the person a few months ago
that was evidently looking for help in designing a roadside bomb, but a
spark gap creates an infernal amount of RF noise...

--
Cats, coffee, chocolate...vices to live by
Click to expand...
I am looking to make a unidirectional spark. I also thought of using
like the old days a rotary spark gap, but with a 3600 rpm motor, even
with 10 contacts around I get 3600rpm/60 =600rps with 10 contacts 6000hz. I guess 6000hz is good enough.
Also with a higher voltage, could I increase the resistance.?

JP
 
On Mar 4, 3:20 pm, lerameur <leram...@yahoo.com> wrote:
On 4 mar, 14:27, Ecnerwal





MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote:
In article <K-OdneKLsMMhmQ3WnZ2dnUVZ_tCdn...@web-ster.com>,
 Tim Wescott <t...@seemywebsite.now> wrote:

Turn-off becomes an issue.  I know that there are ways to turn off an
SCR on a DC supply, but it's some wacky thing involving an auxiliary
inductor that snaps the current off briefly so the SCR can turn off --
it all looks pretty smoky to me.

It's definitely getting into the realm of tubes (mostly thyratrons)
ruling, though at high amperage the tubes are available, but do tend to
cost a few thousand dollars. At the lower amperage ranges, if you stick
to those tubes that are still commonly available they can cost a lot
less than silicon to do the same job.

On the third hand, the application becomes highly suspect as I can think
of a number of nefarious uses this might be aiming towards I wouldn't
care to help with. Not quite as blatant as the person a few months ago
that was evidently looking for help in designing a roadside bomb, but a
spark gap creates an infernal amount of RF noise...

--
Cats, coffee, chocolate...vices to live by

I am looking to make a unidirectional spark.  I also thought of using
like the old days a rotary spark gap, but with a 3600 rpm motor, even
with 10 contacts around  I get 3600rpm/60 =600rps  with 10 contacts > 6000hz.  I guess 6000hz is good enough.
Also with a higher voltage, could I increase the resistance.?

JP- Hide quoted text -

- Show quoted text -
Click to expand...
You could go higher.

600 volts is certainly not a HUGE voltage.
 
On Mar 4, 6:25 pm, sparky <sparky...@yahoo.com> wrote:
On Mar 4, 3:20 pm, lerameur <leram...@yahoo.com> wrote:



On 4 mar, 14:27, Ecnerwal

MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote:
In article <K-OdneKLsMMhmQ3WnZ2dnUVZ_tCdn...@web-ster.com>,
 Tim Wescott <t...@seemywebsite.now> wrote:

Turn-off becomes an issue.  I know that there are ways to turn off an
SCR on a DC supply, but it's some wacky thing involving an auxiliary
inductor that snaps the current off briefly so the SCR can turn off --
it all looks pretty smoky to me.

It's definitely getting into the realm of tubes (mostly thyratrons)
ruling, though at high amperage the tubes are available, but do tend to
cost a few thousand dollars. At the lower amperage ranges, if you stick
to those tubes that are still commonly available they can cost a lot
less than silicon to do the same job.

On the third hand, the application becomes highly suspect as I can think
of a number of nefarious uses this might be aiming towards I wouldn't
care to help with. Not quite as blatant as the person a few months ago
that was evidently looking for help in designing a roadside bomb, but a
spark gap creates an infernal amount of RF noise...

--
Cats, coffee, chocolate...vices to live by

I am looking to make a unidirectional spark.  I also thought of using
like the old days a rotary spark gap, but with a 3600 rpm motor, even
with 10 contacts around  I get 3600rpm/60 =600rps  with 10 contacts > > 6000hz.  I guess 6000hz is good enough.
Also with a higher voltage, could I increase the resistance.?

JP- Hide quoted text -

- Show quoted text -

You could go higher.

600 volts is certainly not a HUGE voltage.
Click to expand...
Ok here is the circuit I am trying to replicate. Some of you will say
it is not possible, it is not concrete, but hey I am just trying it
out.
Like I said , I just want to make a simple circuit with a capacitor
discharging through a spark gap for now, nothing else.
http://www.energeticforum.com/renewable-energy/3235-gray-tube-replication-2..html&usg=__iSdcL6jpOkRkqf7S8vhO8UyJzew=&h=711&w=831&sz=132&hl=en&start=6&sig2=-iiXL_uogSvS1uj0DcYeXw&um=1&itbs=1&tbnid=ZeLwLSgYlT4p6M:&tbnh=123&tbnw=144&prev=/images%3Fq%3Dgrey%2Btube%2Bbedini%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26sa%3DN%26rls%3Dorg.mozilla:en-US:eek:fficial%26tbs%3Disch:1&ei=bDGQS7j0N8_I_gbih4nVDA

Also, in the schematic shown, there is a diode that seems to be on
backwards, but some dud on the web site says it is not.. I still think
it is on backward, can somebody has an explanation for that. The
circuit is doable, the effect well not so much I think
thanks
JP.
 
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