 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
hdwysong(at)GMAIL.COM
Guest
|
 Posted: Wed Mar 29, 2006 6:45 pm Post subject: very sensitive current monitor? |
 |
|
Has anyone here come across an affordable (< $50) current monitor
(preferably hall effect) with a max range of ~1 A? I'm looking for
something that is usable with scaling of mV/mA rather than mV/A.
The form factor of those little ampsense units is perfect... but the
sensitivity offered by their smallest unit (25A) just isn't sensitive
enough.
Thanks for any guidance you can offer!
D
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
 |
nuckollsr(at)cox.net
Guest
|
| Posted: Thu Mar 30, 2006 5:13 am Post subject: very sensitive current monitor? |
|
|
At 08:48 PM 3/29/2006 -0600, you wrote:
| Quote: |
Has anyone here come across an affordable (< $50) current monitor
(preferably hall effect) with a max range of ~1 A? I'm looking for
something that is usable with scaling of mV/mA rather than mV/A.
The form factor of those little ampsense units is perfect... but the
sensitivity offered by their smallest unit (25A) just isn't sensitive
enough.
Thanks for any guidance you can offer!
|
You can get more sensitivity from these products by passing
the current carrying wire through the aperture more times.
I've wound as many as 30 turns through the little Amploc
devices for 30x the sensitivity.
If you're needing 1000x the sensitivity, it's going to
be much harder. You may have discovered that the simple
hall devices have quite a bit of retentivity and tend to
take a "set" in the direction of the last current pulse
that makes zero current readings something of a moving target.
This makes it difficult to simply add gain to the device's
output for more sensitivity.
You might consider a "servoed" hell sensor where there are
two windings on the device. One is driven by an op-amp
set up to watch the hall output and then bias the core
so that net magnetic field is held at zero. The second winding is
your sense winding . . . any field generated by this winding
is exactly offset by the op-amp. This makes the retentivity
thing go away and allows you to put lots of gain on the
current measurement in the null winding which is an exact
image (within limits of the op-amp's dynamic limits)
of the current in the sense winding.
Have you considered the low cost, high common mode
instrumentation amps like the AD626? These can be
used with appropriate shunts to get the kinds of
sensitivity you cited also.
Bob . . .
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
