-16x2 display
-Ardunio Pro Mini (5v)
-Sensors: capacitive , dht-22
-8 opto Relays
-B0505S DC-DC converter for galvanic insulation (the Capacitive sensors need this to proper readings)
SD card reader
The pro mini is powered by a 12v 7amp through a 7805 regulator
The 6 relays are powered with a external 5v 1amp PSU, because the pro mini / display crashes from time to time if i power them directly the pro mini. This way the system is stable.
The general aim of the project is to make logs of the differents lectures of the sensors on a SD card reader, for future analisis.
So here is the question: can i power the SD card module from a 5v external PSU as i did with the Relays?
The reason: I'm would like to minimize the PRO mini power consumption, because the B0505S DC-DC is about 1watt and i can't exceed this current draw.
Why not from the output of the 7805 regulator on the 12v 7amp power supply, and the same goes for the SD card reader ? Note that this does not constitute powering them from the Pro Mini
As long as all of the devices have a common GND connection then you should be OK
Perhaps weather station is not the name, is more a "Climate Control for a Green House" They Control irrigation, Fans, Refrigeration, humidity, etc. through the measure of several sensors: capacitive moisture, Temp/Humidity, Light. Many sensors, need galvanic insulation, so i think that making a insultation of the pro-mini will make the sensor readings more stable. But, the DC-DC is about 1watt, so i think that i need to re-design how the devices are powered (from the pro mini). So, the way would be externally.
So far, the relays with external psu work perfect and stable with days and days of testing.
But i never tried powering displays and sd card from outside the pro-mini.
Regarding to the way of powering the sd, please check the last post i made, where i show the design of the system.
