Re: [OT] Automated testing of multimeter board/software...

["Patrick" <patrick@xxxxxxxxxxxx>]

--- In ukha_d@xxxxxxx, Andrew Kilgore <andrew.kilgore@g...> wrote:
>
> Hi all,
>
> I work with a product used by telecom engineers to measure/diagnose
faults
> on telecom lines.
>
> At present we are trying to automate some of testing - starting with
basic
> multimeter functions.
> Ideally, we'd like to have a breadboard of resistors and some method
of
> (preferably automatically) switching "configurations".
>
> For example, suppose the breadboard has 10 resistors (R1 - R10), what
we
> currently have to do is:
> Set our terminals to the ends of R1, run our test, store/confirm
measured
> value
> Set our terminals to the ends of R2, run our test, store/confirm
measured
> value
> etc.

You can get dial-able resistor switch boxes, to avoid the need to
reconnect each time - something like this:

http://www.action-electronics.com/resist12w.htm

But you still have to manually select the test resistance.

If the line voltage is low, then you build a custom test box using an
analogue switch IC such as a 4066, your test resistances, and use a
PIC to co-ordinate a sequence of tests - say pressing a button once to
progress to the next resistance, with the current resistance being
indicated by an LED. The whole thing would be smaller than a packet of
cigarettes.

If the line voltage is outside the specs of a 4066, you could do the
same thing but with suitably rate solid state relays. Battery life
won't be as good though.

HTH

Patrick