On 28/10/2010 12:43, Matt Rhys-Roberts wrote:
> On 28/10/2010 12:05, Michael Watterson wrote:
>> R1 R2 Potential Divider at all the sources and switch the low voltage?
>>
> Great idea, but would prefer to have just the one PD to avoid having to
> calibrate against the tolerances of other ones. Could use precision
> resistors I suppose, but am not yet sure about cost/benefit of that
> compared to finding some suitable switching method.
>
you can divide down to say +/- 12V and use CMOS switch.
Then higher precision for the final attenuator.

What accuracy is needed?

1kV needs 1M Ohm for 1mA, More than 4M7 precision resistors are expensive.
Calculate assuming 4M7 resistors and 47k Ohms. The tolerance of the 47k=20
Ohm resistor can be much worse than the 4M7 as you are dividing by 100
--=20
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