Giga-ohm resistors are not all that common! : ) Especially high-voltage ones.
I owned just a single 1Gohm resistor. I think it cost me about £10, and is useful to 2.5 kV, if it's kept entirely clean I guess.
Such a resistance is so high, normal multimeters are unhelpful. A Megger (Insulation Tester) on the other hand will measure it fine.
A friend sent across his constructed resistors, and it was very good, so here's a photo of it:
There are cutouts between each of the individual surface-mount resistors, to reduce the risk of dust/dirt build-up, which would reduce the resistance and the voltage rating.
I think I may paint over with MG 422C although MG 4226 would be better, I don't have that handy.
Anyway, I thought it was a nice solution reducing the cost of such a resistor to pennies. Each of the boards has two 1 Gohm resistances (2 x 10 x 100Mohm resistors).
Now that I have these and can keep the £10 resistor as a reference, I'm wondering if a high-voltage voltmeter could be a nice project, with a moving coil meter (I have a few moving coil panel meters lying around).
Any ideas/potential applications for these resistors would be great to hear!
(Image source: Google images)
