About this project
A Professional Precision Current Adapter for Multimeters.
The µCurrent turns your multimeter (or oscilloscope) into a powerful and precise current measurement tool!
Utilise the more accurate voltage range of your multimeter to measure precise current. Even expensive precise multimeters can be severely limited on their current ranges by the shunt burden voltage and tolerance.
Measure the standby and sleep current of the latest generation of microcontroller and other digital electronics, energy harvesting devices etc, down to the nanoamp (or even picoamp!) level with superb accuracy.
The µCurrent also works as a precision x100 voltage amplifier.
See my article originally published in Silicon Chip magazine about this project and explaining burden voltage.
Thousands of the original µCurrent are in use all around the world, and it has quickly become the industry standard low cost tool for low power current measurement in modern low power microcontroller based digital electronics. The µCurrent GOLD is the latest design with greatly improved specs over the original design:
- 0.1% vs 0.5% on the mA range
- 0.05% vs 0.1% on the µA and nA ranges
- 300KHz bandwidth vs 8KHz bandwidth
- +/-1.25A vs +/- 0.3A maximum current (& improved mA range burden voltage)
- Shorting switch
With the extra bandwidth you can now measure fast changing “sleep” modes in microcontrollers. The added shorting mode ensures uninterrupted power to your device under test whilst changing ranges. The µCurrent can rival 5 1/2 digit multimeters in accuracy, it is truly a precision instrument.
MADE IN AUSTRALIA!
Most kickstarter hardware projects just "shop the job out" to a manufacturer in china. I take great pride in not doing that, I want to encourage electronics manufacturing here in Australia.
The box is made in Australia, and the units will be assembled and tested here in Sydney under my control using prime spec original parts.
Like the previous version, the design is Open Source Hardware.
The funds all go towards buying parts in production reels and production quantities. Some of the specialised parts have to be ordered in full reels only.
Specifications – µCurrent GOLD
3 Current ranges:
+/- 0-1250mA (20µV / mA burden voltage typical) * switch contact resistance plays a role here. 10uV due to the shunt resistor.
+/- 0-1250µA (10µV / uA burden voltage)
+/- 0-1250nA (10µV / nA burden voltage)
Output Voltage Units: 1mV/mA, 1mV/µA, 1mV/nA
NOTE: You simply read your milivolt multimeter range as if it were mA/µA/nA
Resolution (nA range):
100pA (3.5digit meter)
10pA (4.5 digit meter)
1pA (5.5 digit meter)
<+/-0.05% on µA and nA ranges
<+/-0.1% on mA range.
Output Offset Voltage: <50µV (essentially insignificant on 4.5 digit meter)
Temperature Drift: <10ppm / degC (µA/nA), <15ppm / degC (mA)
Noise: < -90dBV
THD: < -60dB
Battery: CR2032 Lithium coin cell Battery Life (NOT supplied): >50 hours (battery good LED ensures accurate measurement when LED is on).
NOTE: Yes, I know not including a battery really sucks, but it is illegal to ship even such a piss-weak lithium battery in the units by air freight, these are Australia Post's ridiculous rules. If I find a way around this then I will include a battery.
You can discuss the project on the EEVblog forum
Risks and challenges
The design is well proven, and the prototype was built with a production PCB panel, so it's all ready to go. (I may tweak a hole size or overlay a bit)
I have manufactured and shipped many thousands of the older µCurrent design, so I know how to do this.
Being a precision instrument, this project does however use some critical single source parts. I currently have all these parts to hand for a small number of units, also I also have some larger volumes on order already, due for delivery in early January, so I have anticipated this project going ahead and have put down some serious money already.
Once I know how the campaign is going I will be able to confidently order more of these critical parts, above the ones I already have to hand.
However, it is possible that if the campaign gets too big, there is the possibility of long lead times on some parts from the manufacturers (one part is quoted as 12 weeks).
Also, whilst I know the manufacturer has stock of a certain part, and I can get them in a week or so, I cannot control someone snapping up all the manufacturers stock before I can order them and forcing a long lead time.
I do anticipate being able to supply at least a few thousand units if required in the given time frame, so long lead times would be an exceptional case.
Other things like the contract manufacturers screwing something out and delaying this is also a risk to the schedule.
All this is no different to the usual risks of any other electronics hardware production project.
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