From: firstname.lastname@example.org (N. Thornton)
Subject: Re: High Voltage Power Source from Monitor Third Attempt
Date: 16 Nov 2002 17:03:30 -0800
NNTP-Posting-Date: 17 Nov 2002 01:03:30 GMT
Thoremail@example.com (P!erCer) wrote in message news:...
Hi. Dont do it, you plainly dont have enough knowledge to play with
lethal voltages. I coment for your understanding only.
> Some of you may remember me from my previous posts...my goal has been
> to create a high voltage power source out of a monitor that I can use
> to power my lifter (http://jnaudin.free.fr/html/lifters.htm). I am a
> complete electronics newbie, and my first two attempts ended in a
> broken monitor. The first time, it worked well for awhile but then I
> shorted the high voltage and burned out the HOV transistor (I think).
> The second time, I was all set with a resistor in the line
> (220,000ohms). The resistor was only rated at half a watt, but I
> bought 10 so when it blew I could replace it. Unfortunately, my
> device shorted and I saw the spark arc AROUND the resistor (frying yet
> another HOV transistor..actually this one tests fine. But something
> is wrong). The third time, I am going to get it right. I have been
> reading a bunch about electronics, and here is my design:
> I take the high voltage output from the flyback and run it out of the
> monitor through a drilled hole to a glass bottle filled with sand,
> towering high above the table surface.
The mind boggles! Care to tell us why?
> On top of this bottle is a 3x3
> grid of 220K Ohm resistors rated at half a watt, which I understand
> effectively forms a big resistor capable of dissipating 4.5 watts.
Hopelesssly inadequate. little carbon film Rs are typically rated at
200v. For 20kV you'll therefore need, what 100 in series?
> will completely insulate these resistors with 100% silicon goop,
> avoiding the arcing problem that ruined my second monitor.
Wont even begin to.
> From the
> resistor array a thin wire trails to my device.
You need EHT insulated wire, which is by necessity thick. Thin wire
insulation won't withstand 20kV.
> The ground from my
> device then goes into a wire that goes into the monitor and is
> soldered to the metal braid around the CRT.
Soldered to it while its in place? Oops, there goes your eyesight.
> Another wire is soldered
> to this braid, and goes to the end of my discharge probe (a yardstick
> with about an inch of bare wire on the end).
> From what I understand, the resistors should protect the HOV
> transistor a lot more than before (I was supposed to get ones of 240K
> ohms, but couldn't find that particular value).
> According to Ohm's
> law, a current of .11 - .15 amps will flow through my resistor
> (depending on voltage which I cannot measure or predict, should range
> from 25K - 35K)...will that protect the circuitry enough?
not at all.
> I will make
> great efforts to avoid shorts this time, in any case.
> I have to go to karate now, please let me know what you think.
> -Jason T
Good luck mate :) You'll really need it!