Voltage divider circuit PCB ?

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Hi All

 

This seems to be a simple question.

 

I have sensor output between 0 to 5V.

 

My ADC VREF is 2.5V.

 

Therefore I need a simple voltage divider circuit.

 

But I do not want to mod my circuit or solder resistors onto the actual sensor.

 

Is there any PCBs available with SMD resistor footprints and maybe through hole? This can be between my circuit and the sensor.

 

What i am to do is the following

 

Sensor-->(wire) Devider PCB -->(wire) ADC.

 

In short , i am trying to keep it a bit neat.

 

 

Thanks

Regards

DJ

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Can you just add leaded resistors in your cables to the sensor?  use some heat shrink?  You often see such "mods"

PCB would be better from flex reliability & less production hassle.

 

Is there any PCBs available with SMD resistor footprints and maybe through hole? This can be between my circuit and the sensor.

Surfboards, or similar, if you are just building a hand proto.  Or through hole and a chunk of vectorboard ....neither so good for productions

 

You might be much better using Vcc as the adc ref (if Vcc=5 V), especially if your sensor is ratiometric.

 

Maybe wire direct to a leaded divider network in heat shrink.  Don't forget tolerance accuracy, if pertinent.

Gain error can be cal'd out, if you are willing.

 

 

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Fri. Mar 25, 2022 - 05:43 PM
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Veroboard and encase it in black heatshrink.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

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Some are 0.8 mm thick which can be hand cut by paper scissors :

Surface Mount Prototyping PCBs | BusBoard Prototype Systems

 

Flexible PCB | PCB "Fab-In-A-Box" ... The 8min circuit board system (0.13 mm FR4) though some PCB fab have Kapton.

 

"Dare to be naïve." - Buckminster Fuller

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Brian Fairchild wrote:

Veroboard and encase it in black heatshrink.

 

I think this will be the best option .

 

Add 2 10K resistors. 

Thanks

Regards

DJ

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Brian Fairchild wrote:
Veroboard and encase it in black heatshrink.

I did just that once, but for an inline voltage regulator. (SMD Regulator needed some careful extra blobbing of solder)

 

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crying

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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To accommodate 2 resistors and 4 wires (2 In, 2 Out) a universal DS board of 2x2, or 3x1 holes is enough (I prefer 3x1 holes, or 5x1 for mechanical safety).

 

Solder one resistor at each side, add wires, and protect all with heat shrink tube.

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- posting to wrong thread! -

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

Last Edited: Sat. Mar 26, 2022 - 05:47 PM
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Hi Jim 

 

I did manage bto read your post , my Max ADC voltage will be 5V, ref will be 2.5V and device will be powered with 3.3V.

 

 

 

 

 

Thanks

Regards

DJ

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my Max ADC voltage will be 5V, ref will be 2.5V

Please update, since the ADC pin can never go higher than the Vref (or the number will saurate at the upper limit). 

 You can use Avcc as the ref (3.3V if AVR is powered by 3.3v)

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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I am using a i2c ADC. This is the ADC Click 12.

 

My voltage signal max is 5V, this is reason fort question about the voltage divider. This way my Max voltage will be 2.5V.

 

So with Vref set to 2.5V, my Max ADC vin will be 2.5V

Thanks

Regards

DJ

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So with Vref set to 2.5V, my Max ADC vin will be 2.5V

Divide it down a little more, maybe give 2-10% headroom (if you will use the sensor to the limit).  The last thing you want to do is to run out of ADC numbers by hitting the roof.

For example, if I am measuring 20V max, I will scale it so I could measure 21V (or even 24).  Then, never a worry.  Yes, you give up some step size, but you have plenty.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!