Clamp metesr and DC current

[MoiInAust]

Can clamp meters measure DC current using the clamp(as round a car battery
lead)? If so, how do they work? Surely they need a varying current, as in
AC?

 

[Franc Zabkar]

Can clamp meters measure DC current using the clamp(as round a car battery
lead)? If so, how do they work? Surely they need a varying current, as in
AC?

Compact 0-80A Automotive Ammeter:
http://www.siliconchip.com.au/cms/A_30551/article.html
http://www.siliconchip.com.au/static/images/articles/i305/30551_12mg.jpg

- Franc Zabkar

 

[David L. Jones]

Can clamp meters measure DC current using the clamp(as round a car battery
lead)?

Ones that are designed for DC can, yes.

If so, how do they work? Surely they need a varying current, as in AC?

They use "hall effect" sensors that work with DC.

http://en.wikipedia.org/wiki/Hall_effect
http://hades.mech.northwestern.edu/wiki/index.php/Hall_Effect_Sensor
http://www.sensorland.com/PDF/allegrotp002.pdf

Dave.

 

[Chas]

Can clamp meters measure DC current using the clamp(as round a car battery
lead)? If so, how do they work? Surely they need a varying current, as in
AC?

IIRC, before the advent of solid state electronics, they consisted of a
pivoted permanent magnet which aligned itself with the magnetic field around
the cable. This was spring loaded and was linked to the pointer. A cable
groove was included in the rear of the meter, which was placed in contact
with the cable insulation to take a reading.
--
Regards,

Chas.

(To email me, replace "xxx" with letters tango papa golf.)

 

[john jardine]

Can clamp meters measure DC current using the clamp(as round a car battery
lead)? If so, how do they work? Surely they need a varying current, as in
AC?

They use a 'Hall effect' sensor built into the clamp. Can do AC and DC.
Bought one of these last year ... (beware of line break)
http://cgi.ebay.co.uk/DIGITAL-AC-DC-CLAMP-MULTIMETER-AUTOMOTIVE-BATTERY-METE
R_W0QQitemZ400037674266QQihZ027QQcategoryZ294QQssPageNameZWDVWQQrdZ1QQcmdZVi
ewItem
Really weird to be able to clip on and see the direction of charging current
into a battery, or how much current some circuitry is taking.

 

[David]

Good looking product meter fluctuates to much and is unstable. Uses Hall
Effect sensor
http://www.rgb007.com/producer/1/syd/product_g/product_g1-93s.JPG