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From: Tony Williams
Subject: Re: Limiting total wattage for a constant-current dummy load?
Date: Sat, 09 Nov 2002 13:59:53 +0000 (GMT)
References: <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org>
NNTP-Posting-Date: Sat, 9 Nov 2002 14:04:10 +0000 (UTC)
User-Agent: Pluto/1.14i (RISC-OS/3.60)
In article <email@example.com>,
John Muchow wrote:
> One use I had for the constant-current circuit I have is as a battery
> discharger. The V-Fet voltage changes, but definitely not faster than
> 2V/sec. I can play with the R/C constants and find a nice balance
The remark about "near-dc" only referred to the
speed at which you can turn the pot. The response
speed of the const-I sink (to voltage changes)
is unaffected. So no RC tuning required.
> I'll take a look at the 4066 too (it's digital!!). It looks like I
> need to make sure that whatever switch I use is non-shorting.
There should be no trouble with a 4066 clocked
with a /2 flip flop. The R's in series with
each C are there to smooth over any slight
> Hmmm...if I didn't need continuous current adjustment, couldn't I use
> a 2-pole rotary switch with discrete resistors (instead of the
> dual-gang pot)?
You could yes, but that could be a waste of your
current sink's capabilities. Would you really be
ok with 0-10A in (say) 1A steps?
PS; What supply rails do you have available?
+12V was guessed at originally because of
the need to drive the MOSFET's gate, but
you seem to imply only +5V in another post.
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