Re: [CAD_CAM_EDM_DRO] Re: tantalum caps

Mariss Freimanis wrote:

>
> I agree. What amazed me though was the ceramic caps volumetric parity
> with Ta caps.
>
> Just for fun I measured the ERS for ceramic, tantalum and aluminum
> caps. Each cap was 4.7uF/16V
>
> 1) Aluminum 1.285 ohms
> 2) Tantalum 0.410 ohms
> 3) Ceramic 0.015 ohms
>
> The measured inductance of the ceramic cap was a fantastic 7nH.

I get inconsistant results with the GenRad 1693 Digibridge at work.
We had one device (a photomultiplier tube voltage divider) that
gave bad results with film capacitors. I changed to multilayer ceramic
caps, and the signals looked much better. But, I can't see any significant
difference on either D or ESR using the Digibridge. Perhaps the measurement
needs to be made at a different frequency, though.

The 7nH is probably your wire. It only takes a couple of mm of wire
to get 7nH of inductance. I suspect that the Ceramic reading you quote
above may be an anomalous result due to Xc approximately = Xl at the
test frequency, but it certainly looks good.