self-watering flower pot

Thread Starter

NoahL

Joined Mar 13, 2021
3
Hi, I am an economics student and for a school project I have to develop a product. The product that i came up with is a self-watering flower pot. The pot will have reservoir with an dc pump fitted in. The pump has to be activated every week for 4sec by a battery holder. Because I don't know anything about how this could be done, I came here to ask for help. Can someone give me advice on how this could be done with a low cost?
Thanks in advance.
 

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drc_567

Joined Dec 29, 2008
1,156
The description says that it is a variable resistance.. So it is not on or off, but a resistance, that when lowered by more soil moisture, produces a higher output pin signal.
 

Thread Starter

NoahL

Joined Mar 13, 2021
3
The description says that it is a variable resistance.. So it is not on or off, but a resistance, that when lowered by more soil moisture, produces a higher output pin signal.
This is certainly an option I can consider. But is it also possible to simply program a microcontroller so that the power from the batteries flows to the DC pump for 4 seconds once a week? This way all electronics can be hidden in the bottom of our pot.
 

djsfantasi

Joined Apr 11, 2010
7,867
... But is it also possible to simply program a microcontroller so that the power from the batteries flows to the DC pump for 4 seconds once a week? This way all electronics can be hidden in the bottom of our pot.
Yes, that is certainly possible.

Do you have programming skills? Have you programmed a microcontroller before?

Since you want to water for 4 seconds once a week, the timing isn’t critical so you can use the internal clock of a microcontroller. Since you’ll probably run into overflow issues, your week timer should probably be broken into several smaller segments (2-3 days). You will need one analog pin to read the sensor and one digital pin to control the water pump. (with your static timing scheme, you don’t need a sensor.)

If you’re not experienced in microcontrollers, may I suggest an ATTiny microcontroller, a SparkFun programmer and the (free) Arduino IDE.

If you’re not a programmer (even if you don’t have just beginning experience), you will face a learning curve. It’s not impossible, but give yourself sufficient time. A few weeks isn’t unusual. I used to think anyone can learn to program; the operative phrase there is “used to”.
 

drc_567

Joined Dec 29, 2008
1,156
1615654955992.png
... You have one or two options to consider. The microcontroller might work, utilizing a clock/timer shield, for the weekly activation of the pump. Another possibility is using a chip called a comparator, which turns its output on (meaning it goes high) when the input voltage from the moisture sensor drops below a specific value, that can be adjusted using a variable resistor, called a potentiometer.
... The comparator circuit shown above was taken from the paragraph titled
Inverting Comparator Circuit
...
and can be found here:
Comparator Circuits
... It seems that the most efficient method would be using a comparator, which could be tuned or dialed to meet a specific plant's requirement, and would produce a more efficient result. The power supply could possibly be just a 9 volt battery. The one other necessary component would be a transistor interface between the comparator output and the DC pump.
... If it is necessary to comply with the operation specified in the original post, then some type of microcontroller arrangement would be best.
 
Last edited:

djsfantasi

Joined Apr 11, 2010
7,867
The microcontroller might work, utilizing a clock/timer shield, for the weekly activation of the pump.
I don’t think the application requires microsecond response. The internal microcontroller clock is likely sufficient. So, no external “shield” is required. With proper coding (search for “arduino millis overflow”), it will work just fine.

Otherwise, your approach is a sufficient alternative.

With a microcontroller, you can extend battery life considerably by learning how to put the circuit to sleep for most of the four weeks. It’s probably worth learning how to do this on the particular MCU that you choose.
 

crutschow

Joined Mar 14, 2008
27,915
I'm not that familiar with the various microprocessor but wouldn't a PICAXE be good for a newbie with this application, since it can be programmed in the simple BASIC language?
 

Yaakov

Joined Jan 27, 2019
3,589
Hi, I am an economics student and for a school project I have to develop a product. The product that i came up with is a self-watering flower pot. The pot will have reservoir with an dc pump fitted in. The pump has to be activated every week for 4sec by a battery holder. Because I don't know anything about how this could be done, I came here to ask for help. Can someone give me advice on how this could be done with a low cost?
Thanks in advance.
I realize this is a project and so the thing itself is somewhat arbitrary, but just so you are aware what you are up against in ttying to pitch this as something useful, check out “sub irrigation planters”.

Also note that moisture sensors tend to “rot” from galvanic damage, so they have a limited lifetime.
 

GetDeviceInfo

Joined Jun 7, 2009
1,896
Hi, I am an economics student and for a school project I have to develop a product. The product that i came up with is a self-watering flower pot. The pot will have reservoir with an dc pump fitted in. The pump has to be activated every week for 4sec by a battery holder. Because I don't know anything about how this could be done, I came here to ask for help. Can someone give me advice on how this could be done with a low cost?
Thanks in advance.
Are you going to build a prototype or is it just a concept.
Pumping from a reservoir at timed intervals is a simple matter. Pump, batteries, a micro, and transistor should do it. An ‘economically viable’ product however, may demand more.
When do I water the reservoir
How do I charge the batteries
How do I adjust for a cactus compared to a tropical
How do I clean out hard water scale
Will it email me alerts
....

I run a thin film system that pumps nutrient water every hour for 2 minutes. Pump and timer.
 
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