Hello i have a small project involving wireless sensors. I would like to make something that can could use coin cells and last a very long time. I do have 2032 coin cells, Also i have arduino pro mini's 6 of them i just recently figure out how to put the pro mini using the 328p chip into deep sleep to save power. I do have DHT22 Temperature and humidity sensors 4 of them and one Tiny thermistor that came from a old out door Temperature sensor that die on me. On the receiving side i have many LCD screens and uno boards. So my question is could this project work and Where do i start at?
One last thing i forgot is the wireless part of it. I do have only one set of 433mhz rf transmitter and receiver for testing.
Why do you want to use coin cells? You have to be very good at low power circuit design in order to make coin cells cost effective. AA or AAA batteries are far cheaper and will last much longer.
In any case you need to add up all the power requirements and then figure out how long the chosen cell will last.
Hello Jremington you are right AA batteries or AAA batteries would be better. I'm just trying to use what i got. Okay yes i do have AAA batteries, I guess can work to. I will look more into changing it. One thing I'm having problems with figuring out is that i would like to put a sensor outside. But keeping everything in a box i wonder what would be the best sensor for it. problem is the sensor can't be in the case or the case needs wholes in it so it can get temperature from outside. So not sure what to do with it.
My weather station uses an am2320 sensor which is mounted outside the box but in a place sheltered from wind & rain and the direct rays of the sun.
Hello PaulRB thank for the shaing image. That actually looks pretty cool But Where i can put mine is on a side of a house with no power can reach it. I'm going to look over the link you posted. Thank you
You want to put it on the north side of the house, otherwise it is difficult to protect the sensor from the sun's rays, which would affect the temperature reading.
My weather station uses a 4,200mAh, 18650 size li-ion battery, which lasts about 11 weeks between charges. The Wemos chip has WiFi built-in, and sends its data to an internet server to be stored on a database. The circuit also has an attiny85 chip, but this is to monitor the wind and rain sensors, so you would not need that.
The am2320 also senses humidity. If you did not need that, you could use a ds18b20 sensor, which is very small, and you can buy those sensors in a waterproof housing.
Hello PaulRB What i did on the old sensor was to shield it from the sun i put a piece of aluminum square plate bigger then the old broken sensor directly in front of it then offset it a little. And it that seem to work for the old sensor. Wait i totally forgot the old sensor used 2 double AA batteries maybe i can reuse the old housing to make the new one?
maybe i can reuse the old housing to make the new one?
We cannot see the old housing. How can we know the answer?
This is the link for a image of one. It is the same one i have also same yellow coloring over the years :)
Yes, I used to have one of those. I don’t think there will be enough room inside for you to build an Arduino circuit. Here is a picture of some other sensors I have built, but they are for indoors and not waterproof.
The battery shown is a smaller 10440 size and lasts for 3 weeks.
If i take out the LCD which i do not need and the original board and wireless. I have enough room for a pro mini or even just use a breadboard 328p chip on a small pcb. and a 433mhz transmitter also maybe can reuse the old tine thermistor If i can figure out how to make it work. There is also a tiny Humidity sensor as well. But not sure on any of them parts. I think if i remove the housing for the dht22 i can fit it in there it’s small enough.
If i use sleep mode on the pro mini 95% of the time and just wake it up to take the temperature, humidity sensor and transmit on the 433mhz transmitter back to the receiver then go back to sleep How long would the double AA matteries last? Well it be more like 3v.
This project just screams for solar cell battery management.
Hello Arnoldo I was thinking the same thing haha. But i wish i had one :(
Well i mange to power it up using the 2 double AA batteries I put the arduino and everything to sleep for 10 minutes Wake up and take a Temperature reading then go back to sleep. So now i'm wondering what is the cut off voltage for the arduino before it can not power up? sense this is a 5v pro mini running on 3v.