Author Topic: My current ranger keep flicking back between mA and uA in Auto mode  (Read 218 times)

henry1010

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Hello Everyone

First time posting in this forum.
I am encountering this issue wondering if its normal.

My set up  Battery positive --> source   Load --> positive end of my circuit
               Battery negative -->  negative end of my circuit

My circuit uses both attiny and esp12e.  My program was written so the circuit will turn on for 30 seconds then sleep for 16 seconds.
Currently,  when I turn on the circuit with the current ranger. Initially, it will turn on for 30 seconds and sleep for 16 seconds, but after the initial round my circuit it seems to stuck in sleep mode. It will sleep for 16-second wake up for one second then go back to sleep and this cycle continues.  However, when i plug the circuit directly with a lipo battery this will not happen.

can someone shed some light on why the current ranger will do this?  Is it damaged? if so what part do i need to replace?

thank you
henry

Felix

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Re: My current ranger keep flicking back between mA and uA in Auto mode
« Reply #1 on: October 11, 2019, 09:07:02 AM »
Hi Henry,
Which revision is this? (it's on the SMD side, lower left).
Do you still have the calibration values for it? That might help in case they need to be changed.

It might be possible the circuit wakes up too fast, causing a brownout during auto-ranging.
What happens if you add a 10uF capacitor to your power rail in your circuit? How about a 100uF? (this to the regulated power supply that powers your ESP/attiny).

If you take a simple 10K variable resistor (trim pot) and add a 50-100 ohm resistor in series with it, and slowly ramp up from uA to mA range, there should be no flicker, the CR should range smoothly. That's how you know the CR is functional and does its job. As far as how fast it can do that, that is a separate issue and it can be made to switch faster at the expense of some extra noise (seen more evidently on the OLED if you have one, but not on a RMS DMM). That involves sampling the ADC faster.

henry1010

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Re: My current ranger keep flicking back between mA and uA in Auto mode
« Reply #2 on: October 11, 2019, 02:24:43 PM »
Hello Felix,

I got the R1 revision.

"Do you still have the calibration values for it? That might help in case they need to be changed."
>>>Do you know how can i obtain the calibration value?  Yes I have the OLED screen installed on the CR.

"It might be possible the circuit wakes up too fast, causing a brownout during auto-ranging.
What happens if you add a 10uF capacitor to your power rail in your circuit? How about a 100uF? (this to the regulated power supply that powers your ESP/attiny)."
>>> that is a possibility, I will try to add 10uf and 100uf in my power rail.  I assume the capacitor is added outside of the circuit between the positive and negative lead that power line.

"If you take a simple 10K variable resistor (trim pot) and add a 50-100 ohm resistor in series with it, and slowly ramp up from uA to mA range, there should be no flicker, the CR should range smoothly. That's how you know the CR is functional and does its job."

Do you mean building a separate circuit to do that?  Is this something I add to my existing circuit? would you be able to draw a simple sketch to how to wire that?

I really appreciate your help.
Thank you.
Henry

alexsh1

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Re: My current ranger keep flicking back between mA and uA in Auto mode
« Reply #3 on: October 12, 2019, 07:27:52 AM »
Hello Felix,

I got the R1 revision.

"Do you still have the calibration values for it? That might help in case they need to be changed."
>>>Do you know how can i obtain the calibration value?  Yes I have the OLED screen installed on the CR.

"It might be possible the circuit wakes up too fast, causing a brownout during auto-ranging.
What happens if you add a 10uF capacitor to your power rail in your circuit? How about a 100uF? (this to the regulated power supply that powers your ESP/attiny)."
>>> that is a possibility, I will try to add 10uf and 100uf in my power rail.  I assume the capacitor is added outside of the circuit between the positive and negative lead that power line.

"If you take a simple 10K variable resistor (trim pot) and add a 50-100 ohm resistor in series with it, and slowly ramp up from uA to mA range, there should be no flicker, the CR should range smoothly. That's how you know the CR is functional and does its job."

Do you mean building a separate circuit to do that?  Is this something I add to my existing circuit? would you be able to draw a simple sketch to how to wire that?

I really appreciate your help.
Thank you.
Henry

I have had the same issue with R1 in the beginning.
You probably have to modify the sketch.
Check out this thread too:

https://lowpowerlab.com/forum/currentranger/current-ranger-reading-unreadable/

Alex

Felix

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Re: My current ranger keep flicking back between mA and uA in Auto mode
« Reply #4 on: October 12, 2019, 09:35:35 AM »
Henry,
The test circuit with the trimpot is something separate, just to test auto-ranging with a resistive load that you control via the trimpot. It can be powered by a LiPo or 2xAA, something like 3-5V.
As you alter the resistance with the trimpot the load goes from a few hundred uA to a few dozen mA depending on the voltage and actual resistance at that time.
So the CR should autorange when it passes a certain threshold. On the R1 it can be more sensitive but like Alex said, the sketch can be modified.