search

davidkreidler / OpenCO2_Sensor

Arduino Repository for an E-Ink CO2 Sensor using ESP32 and SCD4X
https://www.tindie.com/products/davidkreidler/open-co2-sensor/
MIT License
100 stars 5 forks source link

Revised PCB #14

Closed Blanketier closed 10 months ago

Blanketier commented 10 months ago

I have run out of projects that I can make without spending an ungodly amount of money in R&D and me and a friend thought it would be fun if we mapped out the CO₂ monitor you have posted. You did not post the files for the schematic and board and only posted the images. looking at the schematic I have decided to just make a revised schematic with better power infrastructure and a few other misc. improvements. I was wondering if there is anyway to get in contact with you for you to explain some of your design choices?

davidkreidler commented 10 months ago

Hey here is a good player to ask questions and I would love to see the power infrastructure changes. Thanks! David

Blanketier commented 10 months ago

image is the purpose of this section to switch between battery operated and usb powered depending on weather usb is plugged in?

davidkreidler commented 10 months ago

Yes and to detect if USB is plugged in to go out of battery mode.

Blanketier commented 10 months ago

The more I look at the schematic of this portion I dont think it works as intended and simply works for the wrong reasons. The diode is forward biased and leaks the small amount of current necessary to power the board. I think this only works as a diode-or gate which would be sufficient for this board but is not the best in terms of efficiency.

Blanketier commented 10 months ago

either way the board im making will be using a tps2116 power mux from TI

davidkreidler commented 10 months ago

That's all pretty Standart stuff. Almost every esp32 dev board uses these cheap components to protect the battery and only use it, if USB is disconnected. The MOSFETs is conducting if USB is disconnected. And the diode otherwise conducts power to the device. Using an expensive and not at my supplier lcsc available part is no improvement.