| Author |
Message |
Ian Stirling
Guest
|
 Posted:
Mon Jan 31, 2005 5:26 pm Post subject:
Re: Measuring Current |
|
|
In sci.electronics.design Spehro Pefhany <speffSNIP@interlogdotyou.knowwhat> wrote:
| Quote: | On Tue, 1 Feb 2005 00:36:54 -0000, the renowned "Jim Douglas"
james.douglas@genesis-software.com> wrote:
I saw some of those on Ebay today, It seems to have a scope type thing that
simply wraps around a wire??
snip
If you put multiple wires through the core (like an AC line cord) they
will read about zero, unless there is a fault to ground, as they read
the difference between the two currents.
|
Though there exist probes like this that using some assumptions about the
geometry of the wire, and several sensors closely spaced arouind the
cord, can actually measure the current flowing through a balanced conductor.
|
|
| Back to top |
|
 |
Spehro Pefhany
Guest
|
| Posted:
Mon Jan 31, 2005 7:17 pm Post subject:
Re: Measuring Current |
|
|
On 31 Jan 2005 11:26:06 GMT, the renowned Ian Stirling
<root@mauve.demon.co.uk> wrote:
| Quote: | In sci.electronics.design Spehro Pefhany <speffSNIP@interlogdotyou.knowwhat> wrote:
On Tue, 1 Feb 2005 00:36:54 -0000, the renowned "Jim Douglas"
james.douglas@genesis-software.com> wrote:
I saw some of those on Ebay today, It seems to have a scope type thing that
simply wraps around a wire??
snip
If you put multiple wires through the core (like an AC line cord) they
will read about zero, unless there is a fault to ground, as they read
the difference between the two currents.
Though there exist probes like this that using some assumptions about the
geometry of the wire, and several sensors closely spaced arouind the
cord, can actually measure the current flowing through a balanced conductor.
|
Is it possible to make a hand-held probe to do this?
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
|
| Back to top |
|
|
Ian Stirling
Guest
|
| Posted:
Mon Jan 31, 2005 8:40 pm Post subject:
Re: Measuring Current |
|
|
In sci.electronics.design Spehro Pefhany <speffSNIP@interlogdotyou.knowwhat> wrote:
| Quote: | On 31 Jan 2005 11:26:06 GMT, the renowned Ian Stirling
root@mauve.demon.co.uk> wrote:
In sci.electronics.design Spehro Pefhany <speffSNIP@interlogdotyou.knowwhat> wrote:
On Tue, 1 Feb 2005 00:36:54 -0000, the renowned "Jim Douglas"
james.douglas@genesis-software.com> wrote:
I saw some of those on Ebay today, It seems to have a scope type thing that
simply wraps around a wire??
snip
If you put multiple wires through the core (like an AC line cord) they
will read about zero, unless there is a fault to ground, as they read
the difference between the two currents.
Though there exist probes like this that using some assumptions about the
geometry of the wire, and several sensors closely spaced arouind the
cord, can actually measure the current flowing through a balanced conductor.
Is it possible to make a hand-held probe to do this?
|
AIUI, the probe that I referred to was 'just' another clamp-on probe,
for attachment for the meter of your choice.
Sorry, I don't recall when.
It was probably on sci.electronics, on a thread I was involved in.
"ian stirling" multiple current wire hall
may or may not turn up something on google.
|
|
| Back to top |
|
|
Jim Douglas
Guest
|
| Posted:
Tue Feb 01, 2005 6:36 am Post subject:
Re: Measuring Current |
|
|
I saw some of those on Ebay today, It seems to have a scope type thing that
simply wraps around a wire??
Are they pretty accurate, is the HP a tube based product?
"John Smith" <kd5yikes@mindspring.com> wrote in message
news:cth937024ca@enews4.newsguy.com...
| Quote: |
"Jim Douglas" <james.douglas@genesis-software.com> wrote in message
news:9_idnYKM8aTDZGbcRVn-sg@comcast.com...
I currently have one nice digital VOM. So I measure voltage, then
current,
back and forth having to move the cable each time, which sucks. I want
a
stand-alone ammeter that I can quickly place within a circuit, I think.
I
would rather not purchase another meter just to measure current and am
thinking that this might be something easy to build but didn't find alot
searching so far.
Do you guy's use a separate amp meter for this stuff? I am just a
hobbyist
that likes playing around with things. One goal is to eventually build a
SW
transmitter. Should I try to purchase, build? I would prefer building. I
am
thinking I would like to be able to measure down to the microampere
range.
Thanks for any input!
--
Jim Douglas
www.genesis-software.com
Carrollton, TX USA 75006
Latitude 32.9616
Longitude 96.8916
Hi, Jim -
For my current measurements, I bought an HP 428B (toob-type) off Ebay and
repaired it. The reason I wanted it was so I would not have to break
connections to measure current. Of course, one must have enough slack in
the wire to allow inserting the clamp-on probe.
Just an idea. Good luck.
John
(kes is not required)
|
|
|
| Back to top |
|
|
DaveM
Guest
|
| Posted:
Tue Feb 01, 2005 8:47 am Post subject:
Re: Measuring Current |
|
|
"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:7p1rv0ldima0oiov4k16gd97vbhj913gqj@4ax.com...
No, the listings you referred to are not the HP428 DC current meters that
were mentioned previously. The HP428 meter uses a small clamp-on probe that
saves the user from having to open the circuit to measure current. The
HP428 meter has full-scale ranges from 1ma to 10A. Yes, these are vacuum
tube models, but easy to maintain and use. Well worth what you'll pay on
Ebay for these meters if you need to measure small currents without breaking
the circuit to insert a current meter.
They are not the hallmark of accuracy when compared to the digital
instruments of today's technology; +/- 3% full scale on every range, but
will absolutely get the job done.
The probes are not hall-effect sensors, but are esentially small
transformers that are excited by a 40 Khz signal. The output of the
transformer is modulated by the change in core saturation caused by the DC
current being measured. You can see great pictures of the meter and probe
at
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=25411&item=3866525538&rd=1
(for the next couple of weeks anyway).
--
Dave M
MasonDG44 at comcast dot net (Just subsitute the appropriate characters in
the address)
Never take a laxative and a sleeping pill at the same time!! |
|
| Back to top |
|
|
Jim Adney
Guest
|
| Posted:
Tue Feb 01, 2005 12:20 pm Post subject:
Re: Measuring Current |
|
|
On Mon, 31 Jan 2005 08:17:07 -0500 Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:
| Quote: | On 31 Jan 2005 11:26:06 GMT, the renowned Ian Stirling
root@mauve.demon.co.uk> wrote:
Though there exist probes like this that using some assumptions about the
geometry of the wire, and several sensors closely spaced arouind the
cord, can actually measure the current flowing through a balanced conductor.
Is it possible to make a hand-held probe to do this?
|
I've seen the ad, but I don't think it was particularly "hand held."
We decided that the instrument had to make certain assumptions about
the geometry of the cable you put in there. Or maybe you had to tell
it about the geometry.
In any case, I don't think they made any claims of being able to
measure balanced currents in coax.
-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
----------------------------------------------- |
|
| Back to top |
|
|
|
|
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in