RadioBanter - View Single Post

February 25th 04, 03:41 AM

On Tue, 24 Feb 2004 20:23:07 -0600 (CST),
(Richard Harrison) wrote:

Steve Nosko wrote:
"I wonder if a "true RMS" DVM can handle this?"

So do I. The true rms meter seems a wonderful development to me.

Hi Guys,

The first "True RMS" meter I worked on was from Fluke back in '75. It
was broke and I had to fix it, but most of the components had their
identification numbers scrubbed off and the schematic at that point
was just an outline with gozintas and comesouttas.

Well, Fluke was (is) just up the road from me, and I gave them a call
for details. Nocando came the reply. My first lesson in proprietary
design. Such technology was to kill for.

Today, I can buy far better from Radio Shack at 1/10th the cost.
Still and all, it only works through to voice frequencies (to lazy to
grab the spec sheet). If you want more precision/bandwidth, then
there are complex (non-digital) math chips that do it in real time
through analog multipliers and compressors (log function). One of my
tech gurus, Robert Pease of National Semi, challenges most digital
designs as a waste of time and energy. He successfully offers analog
designs that provide far better stability and accuracy.

73's
Richard Clark, KB7QHC