Ok, perhaps putting up a manual test-rig would be the best then, doing it t=
he "hard" way. Always looking to cut corners:-)
I did notice Mike=B4s words though , just kept it short.
I=B4ll look more into it, and report if I come up with some unexpected clev=
erness. In the meantime, I=B4m always happy with some more pointers on this=
.
Thanks for the tips!
Best
-A
--- In Peter Shute <> wrote:
>
> Mike did say to check them with a calibrator once you'd pre sorted them b=
y resistance.
>
> Peter Shute
>
> Sent from my iPad
>
> On 06/04/2013, at 8:54 PM, "Raimund" <<raimundspe=
>> wrote:
>
>
>
> > Thanks for excellent input everyone!
> > I think I will go for the multimeter-solution.
> > I am currently on the EM172=C2=B4s and getting the 470 ohm across the p=
ad 1 and 3, with a variance of 2-3 (469-472)
> > So am I right that the capsules should be within 0.1 of eachother (f.ex=
470.1 and 470.2)? If so, I need a better multimeter.
> > Secondly, if this is right, am I right to assume one would be lucky to =
get a matched pair out of a batch of ten capsules?
> > Sorry for my lack of insight BTW, I=C2=B4m working on it:-)
>
> Hi Anders,
>
> I think that John Hartog's approach is the way to go.
>
> I'm afraid that measuring the tiny differences of the 470 ohm source resi=
stor does not help here at all. I'm pretty sure the 1% tolerance of the res=
istor has nothing to do with the actual sensitivity differences of the caps=
ules.
>
> What instead matters are the specific tolerances of the internal FET tran=
sistor (its gain), the electret foil and perhaps a few geometric tolerances=
within the capsule. These much more relevant tolerances however cannot be =
measured by a simple multimeter.
>
> Regards,
> Raimund
>
|