18 Oct
2008
18 Oct
'08
2:14 p.m.
On Friday 17 October 2008, Tony Duell wrote:
66 Megohms? I think yoy're likely to exceed the voltaeg rating and
cause flashover long before it burns out by dissipating too much
power.
Really? If my calculations are correct :), a 1/2 W resistor is would
only need to be just under 6000V to exceed the wattage rating, and I
Yes, I'll agree with that.
It requires arcane rites involving ritual sacrifice.
Make sure
you have an elder sigil.
Try sacrificing a blue-blue-blue resistor by overdriving it until
the magic smoke is let out. think would be physically large enough to avoid
flash-over in dry air
(30V per mil works out to 0.2in of gap at 6000V). A small neon sign
The voltage rating of resistors is lower than you might expect. For most
small wire-ended resistors it's only a few hundred volts. The main
problem is intenral flashover between parts of the resisive element --
it's not a uniform block of resistive material, it's more likely to be
helical in structure (possibly a resisive coating on an insulator with a
helical path cut in the coating, thus leaving a helical resistive coating
to form the actual resistor.
I suspect if you took a 66 Meg 0.5Wresistor and slowly increased the voltage
across it, it would fail from an internal flashover long before the
voltage was reached that should burn it out.
-tony