Products > Test Equipment
finding short on motherboards with a shorty (with display)
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nikifena:
Dear Kean, thanks for the notes! You are absolutely right, the battery level calculator 1k divider resistors must be connected after the soft power switch. This divider could be made by 27k resistors since they exist in the current BOM. And yes, the I2C pin must be SCL. kripton2035, the clock and data pins on the Arduino are reversed on your schematics.

And more.
What about removing the current precision opamp gain stage and using only an ADC with built-in PGA with a variable higher gain. There are a couple of up to x128 gain ADC's with 24-bit resolution. The marked in blue  MAX11270 and CS1237 are my favorites for now. What is necessary: fast readings with more digits :)

Anyone with programming skills to write/modify the code?

kripton2035, your design looks better now.

sam_sam_sam, There are cheap PCBs from China with a USB-C connector, a battery charger IC and battery under and over-voltage protection too. Here is a quick example: https://www.aliexpress.com/item/1005001581000751.html
The DIN5 connector has a kelvin wiring to the probes as shown.

Niki

kripton2035:

--- Quote from: Maximilian on April 04, 2021, 05:02:29 pm ---The only problem with it is that the battery discharges quite quickly, I hope this can be solved.
Looking forward to building the upgraded EEV version.
 :-+

--- End quote ---
I never recharged the 9v battery I use for the prototype since the beginning of this project. hours if not days of use really.
yes. it is a mechanical switch, I prefer them to any "auto off" methods that never really off the power for that main reason.
Mechatrommer:
:-+
de_light:

--- Quote from: nikifena on April 04, 2021, 05:08:25 pm ---What about removing the current precision opamp gain stage and using only an ADC with built-in PGA with a variable higher gain. There are a couple of up to x128 gain ADC's with 24-bit resolution. The marked in blue  MAX11270 and CS1237 are my favorites for now. What is necessary: fast readings with more digits :)
Niki

--- End quote ---

I like the idea of your suggestions! Any chance you can release the schematics/gerber files on a Github or something so others can collaborate?
kripton2035:
I've implemented 6 digits to my shorty prototype. 10µΩ resolution. with 16 bits and pgax8.
but it's not stable. only the 5th digit is ok. this is not a precision instrument. not sure if 24 bits will add a lot of usability.
you may have to change a lot of other parts of the design to achieve it.
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