Re: Some more Marx questions (fwd)

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Original poster: Steven Roys <sroys@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Wed, 5 Jul 2006 19:18:30 -0500
From: Dr. Resonance <resonance@xxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Some more Marx questions (fwd)



That's what I am saying ---- make your own HV relays using a simple 
inexpensive surplus (Fair Radio Sales) 120 VAC solenoid to pull the plastic 
lever 1 inch which the other end moves 3 inches.  On the top end you have a 
sparkgap that closes completely and opens 3 inches.  If you are a teacher 
get the local wood or machine shop teacher to help you make up the lever 
part.  It's best if they have access to a lathe to turn parts as necessary.

Dr. Resonance
>
> I was hoping to avoid the use of high voltage relays. I am just a poor
> after-school science teacher, so I have to keep things on the cheap. I do
> have all the stuff to make and program a controller, so all I would need 
> are
> the relays.

You definitely have to completely disconnect the power source before firing 
or you will be buying a lot of HV diodes.

My multiplier circuit can be extended to power just about anything up to 
around 50 kV per stage.  After that voltage, we use X-ray transformers (old 
dental units) to charge up to 200 kV/stage.

We have a big open house on Sept. 9th this fall and if you come you can see 
one in action on a 200 kV 1 uF energy discharge machine --- we blow up 25 ft 
long copper wires with it!!


>
> Could I use a Villard style multiplier circuit instead? Looking at it, it
> seems it would work. Although it would be nice to be able to completely
> control the system as you describe. Maybe I'll poke around and see what I
> can come up with in terms of HV contacters.
>
> Thanks for the help. I have built a 5 stage cap/spark gap setup, now to
> figure out how to power it...
>
> Jonathan
> www.madlabs.info
>
>
> ----- Original Message -----
> From: "High Voltage list" <hvlist@xxxxxxxxxx>
> To: "hvlist" <hvlist@xxxxxxxxxx>
> Sent: Monday, July 03, 2006 4:07 AM
> Subject: Re: Some more Marx questions (fwd)
>
>
>> Original poster: Steven Roys <sroys@xxxxxxxxxx>
>>
>>
>>
>> ---------- Forwarded message ----------
>> Date: Sun, 2 Jul 2006 11:04:24 -0500
>> From: Dr. Resonance <resonance@xxxxxxxxxx>
>> To: High Voltage list <hvlist@xxxxxxxxxx>
>> Subject: Re: Some more Marx questions (fwd)
>>
>>
>> The circuit I supplied works fine --- we use it on some of our Marx
>> generators.  Just be sure to use a PLC or other timing device to
>> automatically disconnect the power supply from the Marx circuit just 
>> prior
>> to firing --- if connected the back pulse could damage the diodes.  We do
>> this on all of our Marx generators using a cheap $150 PLC to control
> charge,
>> disconnect, and firing relays.  Using a PLC to control the primary
> contactor
>> and separate HV contactor allows for 1 sec buzzer warning, then 20 sec
>> charging, then 1/2 sec disconnect, then 1 sec buzzer, one more sec delay,
>> then firing.
>>
>> The HV charge relay uses a 1 inch stroke solenoid attached to a phenolic
>> strip to multiply (lever action) the stroke by 3 (3 inch spacing) to
>> disconnect the power supply 1/2 sec before the Marx fires.  This is for 
>> 30
>> kV charging --- longer stroke necessary for higher stage charge voltages.
>>
>> Dr. Resonance
>>
>>
>> >
>> > I'm slowly working on my Marx. The 6 kV diodes arrived, so I made some
>> > 42kV
>> > strings with 7 diodes per string. I put them into some nice little 
>> > tubes
> I
>> > had, and the used brass tubing at the ends for the contacts. Fits 
>> > nicely
>> > into a standard fuse holder.
>> >
>> > Anyway, to the questions: The diagram from Dr. R and others for the
>> > voltage
>> > doubler with a center tapped transformer has the ground seperate from
> the
>> > negative side of the doubler. All the Marx schematics I see show the 
>> > arc
>> > going to ground. In my case, I would want the arc to go to the negative
>> > side
>> > of the supply for maximum spark, right?
>> >
>> > It seems however, that arrangment would be hard on the power supply. 
>> > So,
>> > can
>> > anyone point me to a schematic that uses a center tapped transformer
> with
>> > a
>> > doubler to feed a Marx bank?
>> >
>> > Many, many thanks for all the help!
>> >
>> > Jonathan
>> > www.madlabs.info
>> >
>> >
>> >
>> >
>> >
>>
>>
>>
>>
>>
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