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finding short on motherboards with a shorty (with display)

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nikifena:
Dear kripton2035, the auto power-off circuit is not leaky and won't suck the battery. Both MOSFETs are off when the circuit is off and there is no leaky path.

For the current path resistors, I choose 2512 footprint for R2 and 1206 for the 1R resistors. The bigger resistors have higher thermal mass to keep the resistor temperature more stable over time keeping the readings accurate. I added some diode protection for protecting the frontend circuit.

The ADC is pretty good and it has a build-in PGA (programmable gain amplifier) of up to 8x gain which could be used for increasing the range of measured resistance. In this case what about reducing slightly the gain of the differential amp to 10?


Any recommendations are welcome :)

Niki

sam_sam_sam:
nikifena

Can you please show the other end of DIN 5 connector

 and

I am not understanding the USB connector wiring what USB charger are you connecting to this device

 ( have done a lot USB charger devices [ and battery bank packs ] and have never seen one wired this way )
( most of the time the two center pins [ are shorted together or there is a resistor network ] on a USB charger are for sensing the charging current for the device that is plugged in so this where I am confused about what you have done here )

Are U2 U4 and U5 are suppose to be connected together  because I am a little confused here as well

Please do not take what I have pointed out here the wrong way I am just trying to understand what you have here to understand how it is wired together and be able to troubleshoot this device if should ever have to

Thanks

Kean:

--- Quote from: sam_sam_sam on April 04, 2021, 12:07:37 pm ---I am not understanding the USB connector wiring what USB charger are you connecting to this device

 ( have done a lot USB charger devices [ and battery bank packs ] and have never seen one wired this way )
( most of the time the two center pins [ are shorted together or there is a resistor network ] on a USB charger are for sensing the charging current for the device that is plugged in so this where I am confused about what you have done here )

--- End quote ---
For charging nikifena mentioned above about using an off-the-shelf "cheap PCBs from Aliexpress" so I assume the USB Charger component is meant to be one of those.


--- Quote ---Are U2 U4 and U5 are suppose to be connected together  because I am a little confused here as well

--- End quote ---
Yes, they all share the I2C bus using the labelled SDA and SCL nets.  Oh, he called it "SLC "... :rant:

One thing I don't like in the posted schematic is the 2x1k constant load on the battery even when powered off.  It would be better the place that divider on Vcc and only sample it when Q1 is enabled, or even better duplicate the Q1/Q2 high side switch circuit off another GPIO to only supply the divider while reading the battery ADC value (less than 1ms).

kripton2035:
prototype pcb ordered.
last pcb view is below.

Maximilian:
Some time ago I built the same project from the same HackADay article with a Liion battery and it's really nice to have.
It's very handy to have to quickly find shorted capacitors and it has saved me quite some time.

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.
 :-+

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