Sam Goldwasser wrote:
See: http://repairfaq.ece.drexel.edu/sam/hvprobe.htm
Building a voltage divider out of 10, 10M ohm resistors (and suitable
math!) is sufficient and safe.
And if that's what he'd proposed, I probably wouldn't have chimed in at
all. Reread the original post. He said "10 'one meg' resistors in series".
I maintain that the value is too low.
I err on the side of safety simply because there are so many people here
recommending generally unsafe behavior without sufficient explanation of
why it might be OK in THIS case. Note that people (even famous repair
gurus) often fail to read
what's written, as suggested by your own comment above.
Remember that these posts hang around in the archive for a LONG time.
It's easy to imagine some kid reading a random post out of context,
generalizing the snippet of information and killing himself off.
Anybody who has to ask how to build a voltage divider shouldn't be using
their first attempt on a 2KV measurement inside an instrument that has
other sources of lethal voltages...especially when there are a bunch of
commercial HV probes on ebay for cheap. Save your death wish for
something that can save you some real money.
While I'm on a rant, I'll suggest a general process to be used when
posting advice to the web. You're familiar with the game "telephone".
Tell someone what you're about to post. Tell them to pass it on.
Come back a day later, pick someone 3 layers down the chain and see
if what they heard bears any resemblance to what you said. If it's
still safe, post it to the web. Soon you'll get to where you can do
this in your head quickly by reviewing your proposed post with a blank
mind. (I pride myself on my blank mind) The reader has no idea what
you meant.
All they know is what you wrote...then interpreted in their own unique way.
Just cause I got away with it for 30 years,
doesn't mean It's safe to recommend it to a newbie.
mike
However, I do agree with the other posts that if you plan to do more HV
stuff, be on the lookout for a proper HV probe.
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