Re: Capacitor Safety Discharge Method (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 07 Aug 2007 06:26:49 -0700
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Capacitor Safety Discharge Method (fwd)

At 05:45 AM 8/7/2007, you wrote:

>---------- Forwarded message ----------
>Date: Tue, 07 Aug 2007 00:20:49 -0400
>From: Crispy <crispy@xxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: Capacitor Safety Discharge Method (fwd)
>
> >From what I've seen, high voltage relays can be pretty expensive.  I
>think a much cheaper way to construct a device like that would be to use
>pull-style linear solenoids, such as McMaster-Carr #70155K48 .  However,
>a single one of these solenoids would not be suitable if the max voltage
>across the capacitors would be able to jump a 7/8" gap.  Two solenoids
>opposing each other would double the distance.  I'm about to construct a
>test device with two solenoids to do this.  I'll use that above
>solenoids from MCMaster-Carr, with round-headed screws for electrodes,
>and several inches of HDPE for insulation between the solenoid and high
>voltage.


Think inexpensive pneumatic air cylinders...  You can get cylinders 
surplus for less than $10.. look for something with 1/2" bore (or 
smaller,even) and 3-4" stroke.  Make the fixed electrodes something 
like 1/2" copper pipe, and have the air cylinder bridget them with 
another piece of pipe at right angles.  To make it fail safe(r).. 
spring (or gravity) load it so that air pressure is applied to remove 
the short.

Then, you need a cheap solenoid valve (surplus again, or, sprinkler 
valves work,but they're bulky) and a cheap small compressor (there 
are lots of these around.. you don't need much volume, but you do 
need 40 psi or more.  An aquarium pump won't work.  You want what's 
called a 3 way or 4 way valve.

pneumatics are a great way to work with HV, because the plastic 
tubing carrying the air is an insulator, so the cylinder and all the 
mechanical parts can "float" at HV.


Jim