Power Profiler for IoT

Metal garbage can with tight fitting lid is one cheap option

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Stick a 50 ohm resistor on the uFL connector?


I’ve seen a few Linear Tech/Analog Devices app notes that use decorative metal cookie tins for this purpose.

Not a bad excuse for buying some cookies, either. :grinning:

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It has a discrete antenna on board, and being the only sample I have I would try to avoid desolder it…

If you want to go fancy, they make manual RF shield boxes with cable holes. I picked one up for super cheap at an auction a few years back, it’s pretty handy. Definitely would’ve used a trash can if I had to pay full price though. Like this:


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At day job we’ve used a full spectrum from cookie jars to garbage cans to actual shielded boxes. I managed to pick on of the latter at a Hamfest for $40 . Saelig sells Ramsey ones as one example: http://www.saelig.com/category/MFR00066.htm?Screen=CTGY&Category_code=ramsey-faraday-enclosures

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During a past life, we used faraday bags/pouches to keep devices from connecting to towers and routers during transport. Since they are flexible pouches, they may not meet your lab test setup, but it’s a nice piece of kit to know about. As we move towards more connectivity, there are bound to be more times that we want to prevent it. They’re all fairly similar but the “mission darkness” line was the go-to brand. They could be better, they could just have better marketing, but they are well accepted in the digital forensics communities.


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Aren’t we headed toward that time of the year for biscuits in giants tins from Costco?

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Cookie tins are nice. I built a pair of these for isolating RF devices . note the SMA connectors and EMI feed through devices.

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I am working on a power analyzer, more for fun, than a coming product (all though I hope it turns into a product)

@mliberty: How do you handle the temperature drift of the RDSon of the shunt FETs. For the 1A range, you will probably be using a sub 5mOhm FET, and I think one review talked about a 10mOhm sense resistor. So, the best way is just to calibrate out the terminal resistances, FET resistance and shunt.

But, when the FET resistance has 30% of the voltage developed and increases to 50% more resistance at high temperature, it will show up as an error.

One way to solve it is to have seperate sense points for each sense resistor, before the shunt FET, so the FET is out of the equation. Then you need a mux to bring those signals in

Joulescope does not include the voltage drop across the MOSFETs in the shunt resistor voltage measurement. It only measures the voltage across the shunt resistor(s), and very carefully. Layout matters. Carefully qualifying the RDSon of a MOSFET across components, over temperature, and over aging is asking for pain.

Yes, I was thinking it would be difficult with the FET in the loop. That’s the reason for the comment about needing a Mux

The mux is low cost anyway, so no reason to ask for trouble :smile: