conrad / voltcraft vc870

[mullecy]

Seems to have
-ok input protection and
-good precision: 0.1%
-but only in VDC!, VAC is ok, but ohms/amps... are like 1 or 2% ! 
-but a bit expensive (170Euros but I had it with 20% discount so 136E ) but less than a 450E (seen at 550E and even 600E) fluke87V in Europe...
-probes are just ok but not great
-beeps if you don't use the right connectors (like plug in A for V measure)
-min max but min seems to be bugged
-W but only for mains and medium load 0.1W - 2500W for 10s (see Uni-T UT71E video, it has almost the same adapter)
-but slowest continuity test ever (like 0.5s) !


























from http://www.produktinfo.conrad.com/datenblaetter/100000-124999/124603-an-01-ml-VOLTCRAFT_VC_870_DMM_de_en_fr_nl.pdf

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Technical Data
Symbol . . . . . . . . . . . . . . . . . . . . . . . . .Max. 40000 counts (characters)
Measuring rate . . . . . . . . . . . . . . . . . . .Approx. 2-3 measuring operations/second, Bargraf approx.
10 measurements/second
measuring line length . . . . . . . . . . . . .Approx. 90 cm each
Measuring impedance . . . . . . . . . . . . .>10M? (V range)
Operating voltage . . . . . . . . . . . . . . . .9V block battery
Working conditions . . . . . . . . . . . . . . .0 to 30°C (<75%rF), >30 to 40°C (<50%rF)
Operating altitude . . . . . . . . . . . . . . . .max. 2,000 m
Storage temperature . . . . . . . . . . . . . .-10°C to +50°C
Weight . . . . . . . . . . . . . . . . . . . . . . . . .Approx. 380 g
Dimensions (LxWxH) . . . . . . . . . . . . . .185 x 91 x 43 (mm)
Over-voltage category . . . . . . . . . . . . .CAT III 1,000 V, CAT IV 600 V, contamination degree 2
Measurement tolerances
Statement of accuracy in ± (% of reading + display error in counts (= number of smallest points)). The accuracy
is valid for one year at a temperature of +23°C ± 5°C, and at a relative humidity of less than 75 %, noncondensing.
Temperature coefficient: +0.1 x (specified accuracy)/1°C
Direct voltage
Range Accuracy Resolution
400 mV ±(0.1% + 8) 0.01 mV
4 V 0.0001 V
40 V ±(0.1% + 8) 0.001 V
400 V 0.01 V
1,000 V ±(0.2% + 8) 0.1 V
Overload protection 1,000 V; Impedance: 10 M?
Alternating voltage
Range Accuracy Resolution
4 V 0.001 V
40 V ±(1.3% + 5) 0.01 V
400 V 0.1 V
750 V ±(2.0% + 5) 1 V
Frequency range 45 – 1 kHz; Overload protection 750 V; Impedance: 10 M?
TrueRMS in the measuring area of 10 – 100%: Crest factor: max. 3.0 (at 750V max. 1.5)
61
Direct current
Range Accuracy Resolution:
400 ?A 0.01 ?A
4000 ?A ±(0.7% + 15) 0.1 ?A
40 mA 0.001 mA
400 mA ±(1.0% + 13) 0.01 mA
10 A ±(2.0% + 7) 0.001 A
Overload protection: Fuse, measuring time limit > 5 A: max. 10 s with 10 min break
Alternating current
Range Accuracy Resolution:
400 ?A 0.1 ?A
4000 ?A ±(1.6% + 5) 1 ?A
40 mA 0.01 mA
400 mA 0.1 mA
10 A ±(2.6% + 4) 0.01 A
Overload protection: Fuse, measuring time limit > 5 A: max. 10 s with 10 min break
Frequency range 45 – 1 kHz; Overload protection 750 V
TrueRMS in the measuring area of 10 – 100%: Crest factor: max. 3.0 (at 750V max. 1.5)
Resistance
Range Accuracy Resolution:
400 ? ±(1.0% + 13) with REL function 0.01 ?
4 k? ±(0.7% + 15) 0.0001 k?
40 k? 0.01 k?
400 k? ±(0.7% + 5) 0.1 k?
4 M? 0.001 M?
40 M? ±(2.0% + 7) 0.01 M?
Overload protection 1,000V; Measuring voltage: Approx. 0.3 V

Capacity
Range Accuracy Resolution:
40 nF ±(3.3% + 26) with REL function 0.001 nF
400 nF 0.01 nF
4 ?F ±(2.6% + 26) 0.0001 ?F
40 ?F 0.001 ?F
400 ?F 0.01 ?F
4 mF ±(6.5% + 26) 0.0001 mF
40 mF Not specified 0.001 mF
Overload protection 1,000V
Frequency
Range Accuracy Resolution:
10 Hz to 40 MHz ±(0.1% + 5) 0.001 Hz to 0.001 MHz
400 MHz Not specified 0,01 %
Overload protection 750V
Sensitivity (10 Hz – 40 MHz): 200 mV; Amplitude max. 30 Veff (ms)
DC loop current measurement
Range Accuracy Resolution:
0 – 100 % ±(1.3% + 2) 0,01 %
Overload protection 1,000V
Temperature
Range Accuracy* Resolution:
-40 to +40 °C ±(2.6% + 33)
+40 to +400 °C ±(1.3% + 20) 0.1 °C
+400 to 1000 °C ±3,3%
* without sensor tolerance
63
Diode Test
Test voltage Resolution:
Approx. 4.3 V 1 mV
Overload protection: 1,000 V
Acoustic continuity tester
Test voltage Resolution:
Approx. 1.2 V 0.01 ?
Overload protection: 1000 V, measured range max. 400 ? ; <20 ? continuous sound
Power measurement
Function Range Accuracy Resolution:
Real power “W“ 2500 W ±(2,6% + 13) 0.1 W
Apparent power “VA” 2500 VA ±(2.6% + 14) 0.1 VA
Voltage “V” 250 V 0.1 V
Current “A” 10 A ±(1.3% + 13) 0.1 A
Effective factor “Cos-Phi” 1 0,001
Frequency “Hz” 50/60 Hz 0.1 Hz
Do not exceed the maximum permitted input values. Do not touch any circuits or
parts of circuits if they can have higher voltages than 25 V Acrms or 35 V DC. Danger
to life!


[mullecy]

It seems that probes suffer from a thin oxidation layer and if you don't use the groove or the tip (not sharp by the way), it's like you have up to hundreds of ohms resistor in series... 

I was pressing quite a lot on the probes...
I was able to get less than 0.1Ohms only
-on the grooved part or
-if pressing like crazy (but that was not stable)

[mullecy]

I have also discovered a bug in the min max function in DC V mode: when you press the button it resets the adc or some circuit and the minimum is 0 or some intermediate value  (with v>0) (for v <0 the max is wrong...)
I think I'll send it for a repair/firmware update...