In message
<64D32EE8B9CBDD44963ACB076A5F6ABB0263F54F@Mailbox-Tech.lecotech.local>,
dated Thu, 7 Mar 2013, "Kunde, Brian" <[email protected]> writes:
Do you make your own bleed-off cables (with two 470K? resistors). If
so, what kind of resistors do you use? I’ve seen different labs use
different types of resistors which I think can make a big difference.
Indeed, but there need be no anxiety; metal-glaze resistors rated for
operation at kilovolts are available and not costly. For example:
http://www.vishay.com/ppg?28733
>One lab I was at used surface mount resistors mounted on a small PC
>card which was encapsulated in potting compound. Though it seemed like
>a good idea I have my doubts.
So do I; I doubt the potting compound is rated for many kV/mm!
>I've heard metal film or thin film resistors can arc or track over the
>surface.
Those rated at 100 V, 250 V or 500 V certainly can.
>One lab I was at used huge wire wound resistors but they can arc
>between the windings at high voltages. I've been told that carbon
>composition resistors are the best and get the larger wattages such as
>1 watt or larger. We use 2 watt Carbon resistors which work well at
>8kv.
But they notoriously go high in value when repeatedly subjected to high
voltages. And you might not know that had happened.
--
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
SHOCK HORROR! Dinosaur-like DNA found in chicken and turkey meals
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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