Author Topic: Watts from one ADC pin  (Read 1043 times)

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Offline metrologistTopic starter

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Watts from one ADC pin
« on: March 29, 2018, 05:52:53 pm »
Is it possible to figure out DC watts if you have just one ADC available? I'm currently using two to measure voltage and current.
 

Offline Twoflower

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Re: Watts from one ADC pin
« Reply #1 on: March 29, 2018, 06:16:36 pm »
 

Offline MrAl

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Re: Watts from one ADC pin
« Reply #2 on: March 29, 2018, 06:19:11 pm »
Is it possible to figure out DC watts if you have just one ADC available? I'm currently using two to measure voltage and current.

Hi,

Well you could use an analog switch, but you'd have to switch it from one channel to the other which would take a DIGITAL output pin.  So you'd save an analog pin but use up a digital pin.

There are other ways but require some external circuitry.  For a simple example, use a second small low end uC to measure the power and send it to the 'master'.

 

Offline metrologistTopic starter

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Re: Watts from one ADC pin
« Reply #3 on: March 29, 2018, 07:25:03 pm »
I think I have a few SPDT ICs around, and plenty of extra digital pins.  :clap:

I might have a specific question once I figure out which chips I have.
 

Offline MrAl

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Re: Watts from one ADC pin
« Reply #4 on: March 30, 2018, 02:44:05 am »
I think I have a few SPDT ICs around, and plenty of extra digital pins.  :clap:

I might have a specific question once I figure out which chips I have.

Hi,

Oh that's great.  If you have just one digital pin then you can multiplex one analog channel into two, and if you have two digital pins then you can multiplex into four analog channels using just one ADC input pin.

There are cheap analog switches that can do 8 channels but for 8 you would need 3 digital pins unless you use only two of the channels.
« Last Edit: March 31, 2018, 05:11:20 pm by MrAl »
 


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