So noted. I didn't have my meter opened up, nor the parts list handy. I just went by the manual but mistakenly omitted the "k". Whatever resistor R25 is, apparently a 27k, disconnecting it does cause it to not auto shut off and adding a switch on that does make it more user friendly to me.
John
To: TekScopes@...
From: TekScopes@...
Date: Fri, 8 Apr 2016 20:08:04 -0400
Subject: Re: [TekScopes] ESR meters (again)
Hi John, and others,
After some researched I confirmed the following >>>> below,
Your info is incorrect, as well as the manual info on this modification,
R25 is a 27K not 47 ohms as you mentioned, nor is it a 47k as the manual
mentioned, the parts list confirmed it as a 27k, I also checked it and it
is a 27k, so both you and the manual are misleading,
I have both the Blue ESR and the EVB ESR, which are both the same Bob
Parker design, I don't have a Dick Smith ESR, but I have the manual for it
and the other two I mentioned and all three ESR meters, are the same design
by Bob Parker, with the components in different locations and numbering,
I hope this will help someone here,
v44kai.....Joel.
On Sat, Mar 26, 2016 at 2:31 PM, John Clark johnclark05@...
[TekScopes] <TekScopes@...> wrote:
Dave,
I'm not sure how helpful I can be with my little knowledge (relative to
most everyone else here) but I did purchase a Blue ESR meter kit just a few
months ago and enjoyed putting it together myself. I have been successful
in accurately testing caps while still in circuit with same results out of
circuit so its claim of being able to accurately test caps in-circuit
without energizing other components seems accurate in many cases. There
obviously may be cases where out of circuit is still better.
The only thing I found that I didn't like about it was that the auto
shutoff would activate too soon. As such, I'd have to re-zero it each time
it auto shut off. There is an option to disable auto shut off when you
build it by disconnecting R25, a 47ohm resistor. Instead of just doing
that, I slightly modified a very small switch I bought from Mouser and
added it to the top of the board, next to the on-off switch, and ran wires
down to R25 so I now have the option to either make it stay on all the time
if I'm testing multiple caps, or it can be in the auto shutoff mode for
battery saving if I'm only testing one or two caps. A bit of extra work
but makes it more versatile.
From the documentation: "The Blue ESR is an AC ohmmeter with an equivalent
test frequency of about 100kHz and capable of measuring non-inductive
resistances from 0.01 to 99 ohms. It creates a 500mV P-P (open circuit)
burst of 8usec pulses at a 2kHz rate, repeated several times per second so
it can also be used as a signal source." I was able to connect my 475 to
it and see that signal.
One thing the instructions say is that it can produce unsteady indications
if its test leads pick up strong horizontal deflection signals so you need
to keep it away from CRTs when making measurements.
It has done what I've needed it to do but my requirements may be much more
basic than yours. It's probably a little bit expensive compared to building
one yourself...there are many home-made instructions out there...but this
one is pretty nice.
John
To: tekscopes@...
From: TekScopes@...
Date: Sat, 26 Mar 2016 13:43:12 -0400
Subject: [TekScopes] ESR meters (again)
I know over the years we have flogged the topic ESR meters to death
but
it has been awhile
I am in the process after several moves in the last two years of getting
my lab set back up before I tackle a sick FG504. To my dismay my old ESR
meter has become the victim of battery leakage to the point of not
trusting it even if i could restore it , Several green and possibly
missing traces etc
I went out to Evil-Bay to look for a new one to a bewildering array of
"new and improved" models. Anyone have hands on experience with a an
ESR Meter they purchased in the last 6 months?
Please, please do not respond unless you have purchased something in
the last 6 months, Please reviews of recent purchases ONLY. No anecdotal
stories about how much you love your Geewhiz Model 300 you bought 5
years ago (Which is no longer available)
Dave
--
Dave
Manuals@...
www.ArtekManuals.com
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Trevor J. Liburd (N.T.R.C. St. Kitts/Nevis)
v44kai.....Joel.
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