CP-06 current clamp

[R_G_B_]

I got this current clamp for measuring low currents at frequency of no more than a  5KHz, seems to work ok a low currents in the milliamp range and above. looks ok on the outside on the inside its a different story. Made in China!

its ok for Automotive work measuring parasitic drain etc.

Someone else did a review here:

http://benkrasnow.blogspot.co.uk/2011/07/product-review-cp06-low-cost-acdc-clamp.html

can be got from ebay

or from here:

http://www.sedmm.com/cur.asp

R_G_B

[borjam]

I've just received one (dirt cheap even though I had to pay 35 euros in Spain due to customs processing and 21% VAT) and at least trying with the lab power supply, a multimeter and the oscilloscope I get useful intensity readings on the oscilloscope my extremely über high end, NASA-budget-no-less Rigol DS1074Z.

I got the probe mostly out of curiosity after reading the review mentioned, and I am sure it can be useful even though I will mostly use a µCurrent for my microntroller measurements. But, for the price, the thing is amazingly accurate.

Some data points. The PS is an AIM-TTI EL302R, a Fluke 87V using the amps socket (not the mA/µA as I am surpassing 400 mA) and the Rigol DS1074Z "Enhanced Editlol".

The current probe has three ranges:

• 400 mA (1 mV/mA, max 0.5 A)
• 4 A (100 mV/A, max 5 A)
• 40 A (10 mV/A, max 50 A)

The thing is noisy. With 200 ms/div horizontal, 5 mV/div vertical, and the power supply set to 4 mA (4.7 mA according to the 87V), the oscilloscope is measuring an average of 4.3 mA, but with a peak to peak noise of 18 mA, that with the 20 MHz filter engaged. That's for normal capture mode. In high res, noise is around 9 - 10 mV peak to peak, but the reading is worse, averaging 4.3 mA more or less.

Setting a more realistic scale on the oscilloscope, 50 mV/div, the noise is not that apparent (still in high resolution mode) and, for example, 4.5 mA on the 87V translate to 4 mA on the oscilloscope. Raising the power supply to 10.0 mA (87V) the oscilloscope is measuring an average of 9.9 mA, not bad! (I am hitting clear each time I change the intensity setting on the power supply, and waiting for several seconds).


At 100 mA (87V fluctuating between 99.9 and 100.1 mA, which is the precision limit of the multimeter anyway) the oscilloscope is measuring between 99.5 mA and 100 mA.

So it seems it can measure some mA with a reasonable accuracy. I am interested on doing some tests with an ESP8266, timing some sensor readings and WiFi transmissions together with their timings, and this seems to be suitable. Actually I will be using a µCurrent as well, which will be especially useful to measure sleep times.

I haven't tried with AC, and I haven't tried the 40 A range. I will probably try this weekend when I use the HF transceiver.

[joeqsmith]

I had read his blog and watched his video.  If you have a way to measure the roll off, post it up if you would.

[borjam]

I had read his blog and watched his video.  If you have a way to measure the roll off, post it up if you would.

I'll try to set up a test. According to the manufacturer, 10 KHz at -3 dB.

http://www.sedmm.com/product.asp?productid=67

They have a more expensive model, CP-07, which can reach 500 KHz, and they state a rise time: 1.5 µs.

[joeqsmith]

In the video you link, he talks about 2 or maybe 5KHz but did not know.   Two things I noticed when he ran that last test.  First was that the probe is only rated for 40A.  On the UT210E, if I smack it hard with a pulse like that, it may need to be degaussed.  He never shows a DC test after that but I wonder what the offset was before and after.     The other was he has states the current from the shunt is 200A/div.  The clamp was set to 10mV/A and scope was 2V/div, or he says should be the same scale.   

I attempted to measure the 3dB point of the UT210E and believe the front end is in the 5KHz range.    His 200A capacitor dump test was with the scope set to 0.1 mS /div.   Attached is showing a 5A or so pulse with the UT210E set to the 20A range.  Pink is the shunt, yellow the probe.  0.05 mS/div.   Looks much better than he shows. 

Did not make much sense to me.  I wonder if the probe had saturated (maybe not the magnetics but the amplifier and maybe this is why the response looks so poor.   Even if you did a 5A pulse like I show, that would be great!   

Thanks for your help.

[alank2]

I have a couple of these PDI CA60 clamps:

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR10.TRC0.A0.H0.Xpdi+ca60.TRS0&_nkw=pdi+ca60&_sacat=0

I replaced one of them with a BNC cable so I could connect it directly to a scope.  It does have some noise, but I did a test on it to see where it starts to roll off frequency wise.  My frequency generator can output to 50ohm so I connected it to a 50ohm resistor and used the clamp to measure the current.  2.5 VRMS /50 = 0.050 ARMS * conversion factor 1000/10 = 5 mVRMS.  At 90 kHz it hit the -3db (0.7071) point.

[joeqsmith]

That's impressive.  I was looking at their specs and they had something about it being usable to 20KHz.   Amazon search shows "Frequency Response 40Hz - 20KHz"       

I have a couple of these PDI CA60 clamps:
....
At 90 kHz it hit the -3db (0.7071) point.

[alank2]

Do you think it might be less capable at larger currents?  I only tested it at the 50mA RMS because that is what my function generator can do.

[joeqsmith]

It's possible.  You could try a step as well as see what the edge looks like.