From: Lizard Blizzard
Subject: Re: hi-capacity voltage controlled capacitor?
Date: Wed, 09 Oct 2002 07:57:43 -0700
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Winfield Hill wrote:
> Lizard wrote...
>>I was over at Fry's the other day and stopped by the test equipment
>>aisle. I looked at some bench power supplies, and I was dissapointed
>>when I looked at the Agilent, now apparently back using the name HP,
>>power supply. The V adj pot is a single turn, and it's difficult to
>>adjust accurately. Years ago we could have bought a ten turn pot...
> The power supply you saw was pre-spinoff, test equipment is strictly
> Agilent in the post HP-computer dominance game. Now HP means printers.
> As for 10-turn pots, yes some HP and Agilent models used 1 turn vs 10
> turns as cost differentiators. However the popular new Agilent models
> still use 10-turn pots, or 12-bit D-A converters with optical-encoder
> knobs and 5-digit readout. I'd call that an improvement. Another nice
> Agilent development in the last 5 years: DC dynamic sources. These have
> 12-bit D-A voltage and current-mode programming along with sensitive
> 16-bit A-D metering. With dual-range current monitoring that works over
> a million-to-one range and has 15us measurement rates. Try that with
> your classic HP power supply. :-)
I'm all for getting something that's an improvement on what I see for
'consumer' type bench supplies. B&K just came out with one that has a 4
digit digital readout, which lets one resolve the current down to 1 mA,
which is what I'd prefer. The usual 3 digit meter only gives 10 mA res.
(anyone can buy an autoranging DVM for a few tens of dollars, so why
can't I find one already built-in?) I'd also like to get the current
adj. range down to 1 mA, but everything I see doesn't go that low. I
saw a Kepco switching power supply module that might do it, but I'd have
to add meters, pots, panel, etc. What I'm looking for is something that
will do what I need for something less than the price of an arm and a
leg. Maybe less than a kilobuck would be my price range. Or else I'd
have to butcher up a PS and void the warranty to install a Bourns
Helipot in the front panel, and it would look awfully strange having a
DVM bolted/strapped to the side.
> - Win
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