Author Topic: Current Measurement Device  (Read 658 times)

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Offline fedimakniTopic starter

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Current Measurement Device
« on: June 29, 2020, 09:27:30 am »
Hello,

Currently I am doing a current measurement device based on ucurrent from Dave but i want it to be switched from a microcontroller. ( i chose a raspberry Pi for that - I know it's an overkill but don't take care about it )

I attached the schematic below i am using an SSR to make switching CPC1705Y: Datasheet: http://www.ixysic.com/home/pdfs.nsf/www/CPC1705Y.pdf/$file/CPC1705Y.pdf
I would like to have an idea if i will face any problem with this design?
Is there any limitation
What things i could improve?

Looking forward for your feedback.
Thanks.
 

Offline Dave

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Re: Current Measurement Device
« Reply #1 on: June 29, 2020, 10:51:44 am »
Those SSRs are designed for unidirectional operation. The measurements are going to be skewed when you forward bias the substrate diodes in those.
You might also want to check the leakage current through them as well, because they might pose a problem on the nanoampere range.

Those are also rather fast amplifiers for feeding an 860 Sps ADC. You need image reject filters.
<fellbuendel> it's arduino, you're not supposed to know anything about what you're doing
<fellbuendel> if you knew, you wouldn't be using it
 

Offline Ian.M

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Re: Current Measurement Device
« Reply #2 on: June 29, 2020, 12:07:39 pm »
Additionally, you've got insufficient drive to guarantee the SSRs get turned hard on, and even if you fix that, the on resistance of K2 is several times greater than the resistance of the shunt R1, so the high current range will be unusable, grossly overreading by anything up to an order of magnitude.
 


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