Isolated Detection of Current Flow

M

Manvinder Bhullar

Guest
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Thanks
Manvinder
 
Manvinder Bhullar wrote:
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Thanks
Manvinder
Click to expand...
If no current value "in between" is allowed, your risetimes are
zero and you should be able to detect the radiation from the track
as it rings in response to the stimulus. Heck, it may even give off
light ;-)

It might be useful to post more about the problem. Often/usually/almost
always, problems that start out like this can be solved in a much more
conventional/simpler way.
mike

--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Honda CB-125S $800 in PDX
Yaesu FTV901R Transverter, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/
 
Manvinder Bhullar wrote:
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Thanks
Manvinder
Click to expand...
You could use a hall-switch like this one
http://www.infineon.com/cgi/ecrm.dll/ecrm/scripts/public_download.jsp?oid=28681&parent_oid=29142
--
ciao Ban
Bordighera, Italy
 
I read in sci.electronics.design that Manvinder Bhullar
<mbhullar@tm.net.my> wrote (in <27c42ac5.0403172352.101114ab@posting.goo
gle.com>) about 'Isolated Detection of Current Flow', on Wed, 17 Mar
2004:
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Current transformer.
Click to expand...
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On Thu, 18 Mar 2004 13:10:15 +0000, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Manvinder Bhullar
mbhullar@tm.net.my> wrote (in <27c42ac5.0403172352.101114ab@posting.goo
gle.com>) about 'Isolated Detection of Current Flow', on Wed, 17 Mar
2004:
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Current transformer.
Click to expand...
John, you just invented a DC transformer?
 
"Reinier Gerritsen" <reinier.I_HATE_SPAM.gerritsen@NO_SPAMchampionchip.nl>
wrote in message news:h77k50t9dev3lse9ioqour0qb8urkb5hnr@4ax.com...
On Thu, 18 Mar 2004 13:10:15 +0000, John Woodgate
jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Manvinder Bhullar
mbhullar@tm.net.my> wrote (in <27c42ac5.0403172352.101114ab@posting.goo
gle.com>) about 'Isolated Detection of Current Flow', on Wed, 17 Mar
2004:
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Current transformer.

John, you just invented a DC transformer?
Some systems are sold as 'current transformers', that are plug compatible
Click to expand...
with the normal versions, and use a Hall-effect sensor. I suspect this is
what was being thought of. These are often marketted as 'HECT' devices (Hall
effect current transformers), yet support both AC ad DC operation (with no
'transformer' really being involved).
LEM do a seperate Hall effect sensor, that at 5mm spacing from a single
conductor, has a full scale of 3A, and with a suitable comparator, this is
fully capable of detecting currents at this sort of level.
If the unit is stationary, one of the 'needle amplified' magnetic compass
systems, could also detect this sort of field.

Best Wishes
 
I read in sci.electronics.design that Reinier Gerritsen <reinier.I_HATE_
SPAM.gerritsen@NO_SPAMchampionchip.nl> wrote (in <h77k50t9dev3lse9ioqour
0qb8urkb5hnr@4ax.com>) about 'Isolated Detection of Current Flow', on
Thu, 18 Mar 2004:
On Thu, 18 Mar 2004 13:10:15 +0000, John Woodgate
jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Manvinder Bhullar
mbhullar@tm.net.my> wrote (in <27c42ac5.0403172352.101114ab@posting.goo
gle.com>) about 'Isolated Detection of Current Flow', on Wed, 17 Mar
2004:
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Current transformer.

John, you just invented a DC transformer?
Click to expand...
OOPS! Didn't see that 'DC'. Hall-effect, then, but a fluxgate DC ammeter
is much more interesting.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On Thu, 18 Mar 2004 22:18:35 -0000, the renowned "Roger Hamlett"
<rogerspamignored@ttelmah.demon.co.uk> wrote:

"Reinier Gerritsen" <reinier.I_HATE_SPAM.gerritsen@NO_SPAMchampionchip.nl
wrote in message news:h77k50t9dev3lse9ioqour0qb8urkb5hnr@4ax.com...
On Thu, 18 Mar 2004 13:10:15 +0000, John Woodgate
jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that Manvinder Bhullar
mbhullar@tm.net.my> wrote (in <27c42ac5.0403172352.101114ab@posting.goo
gle.com>) about 'Isolated Detection of Current Flow', on Wed, 17 Mar
2004:
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Current transformer.

John, you just invented a DC transformer?
Some systems are sold as 'current transformers', that are plug compatible
with the normal versions, and use a Hall-effect sensor. I suspect this is
what was being thought of. These are often marketted as 'HECT' devices (Hall
effect current transformers), yet support both AC ad DC operation (with no
'transformer' really being involved).
LEM do a seperate Hall effect sensor, that at 5mm spacing from a single
conductor, has a full scale of 3A, and with a suitable comparator, this is
fully capable of detecting currents at this sort of level.
If the unit is stationary, one of the 'needle amplified' magnetic compass
systems, could also detect this sort of field.

Best Wishes
Click to expand...
Maybe John has some clever circuit in mind that would detect the drop
in inductance of a sense coil wound around the same core when the high
current DC is present. Or perhaps a flux-gate magnetometer.

http://www.ansoft.com/inspiringdesign_02/Flux_Gate_Sensor_Analysis.pdf


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
 
How bout wrapping a few turns of wire around a reed relay?

Manvinder Bhullar wrote:

Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

Am looking for suggestions on various ways of doing this.

Thanks
Manvinder
Click to expand...
--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com
 
"Manvinder Bhullar" <mbhullar@tm.net.my> wrote in message
news:27c42ac5.0403172352.101114ab@posting.google.com...
Hi All,
Say there is a pcb track or wire that carries either 0 mA or 100mA DC
(nothing in between).

I need to be able to sense this 100mA current and produce a one or
zero logic level (TTL or CMOS comaptible), without any electrical
connection to the track or adding any current sensing resistor to the
track.

The response time is not important, so lets just say 'better than 1
second'.

GMR magnetic field sensore like the MKZ51, more sensitive than Hall
Click to expand...

Wim
 
I read in sci.electronics.design that Wim Ton <wimton@blueyonder.co.uk>
wrote (in <Acy6c.19684$F.16399@news-binary.blueyonder.co.uk>) about
'Isolated Detection of Current Flow', on Fri, 19 Mar 2004:
GMR magnetic field sensore like the MKZ51, more sensitive than Hall
Who supplies it and roughly what does it cost? Google didn't find it.
Click to expand...
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
GMR magnetic field sensore like the MKZ51, more sensitive than Hall
Who supplies it and roughly what does it cost? Google didn't find it.
Sorry, typo. I ment KMZ51. Conrad in the Netherlands and Germany sell them
Click to expand...

Wim
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top