Thanks for the mini review, it looks pretty neat. I guess i will need to start messing atound with smd components soon.
Thanks, yeah, it's a useful little device. But I'd recommend at least some experience with SMD before having a go at this kit.
For milliohms, I used to use a power supply in CC mode adjusted as close as possible to e.g. 100mA or 1A using a reasonably accurate meter, then with a pair of Kelvin clips measure the voltage over the resistor.
Now I don't need to do that anymore
Plus it doubles as a nice logging DC voltmeter.
From what I've worked out these are the main features:
MilliOhm Meter:Measurement source current is fixed at around 100mA at max 3V.
There are 2 ranges: 0.2R and 20R.
In the 0.2R range, the resolution goes down to 1 micro ohm.
At the 20R range it's 10 micro ohm.
Overrange is > 50%, as in, you can measure a 30 Ohm resistor, on the 20 Ohm range.
Voltage Meter:150,000+ counts, 4 ranges: 0.1V, 1V, 10V and 100V
Again with > 50% over range. As in, 10V range will measure +/- 15V
Inputs are protected by PTCs and ADC/mcu protected by resistors and diodes.
Common for both Ohms and Voltage are 2 speeds, Slow and Fast. Slow is approximately 1 update per second and fast is updating something like 14-15 times per second.
The display has got a nice uniform backlight.
USB for charging and logging. Output is very simple, just the value currently being displayed and at the selected speed range through an USB/UART 115200 baud 8N1 (not isolated).
It's also got battery voltage monitoring with a visible indicator.
Auto off after 10 minutes (can be disabled).
Power consumption is about 15mA in Voltage Meter mode. And ~110mA as Ohm Meter. Add about 35mA for backlight.
Not sure what the accuracy is, but all ranges can be calibrated against a reference. (positive, negative and zero for voltage and zero plus value for ohms)
The standard reference is a MAX6192A, ADC is 24bit in the C8051F350 and the current resistor is a low tempco type.
It appears to have good accuracy.