This moisture sensor circuit is based on a design by Forrest Mims, and adds a Shunt Ammeter so that the output is 0 to +5 Volts instead of amperes. We are using it for the ITPlants project, so that when soil moisture drops below a minimum, the plant can make a phone call for help. Other call-worthy events will be a thank-you when the plant does get watered, a warning if the plant is watered too often, and a follow-up call if the watering is insufficient. This is going to be one chatty shrub.
hi rob,
i’m wondering if you’ve discovered a circuit for detecting changes in biopotential of the plants, something like this:http://www.borderlands.com/archives/arch/schemati.htm
I’ve built this, and there is some confusion about the op AMP section, with the batteries.
Looking foward to your comments..l
Thanks,
Daniel
We haven’t done anything with biopotential. Mostly we’re concerned with monitoring the basic health of the plant, so moisture, light and soil chemistry are our focus.
How do you calibrate with this circuit reliably?
Dear Sir,
This is a very interesting concept. Could you please elaborate more on the system or provide links or references for the same.
Thank you.
hi
can i ask you a favor to please send me one copy of the whole circuitry for moisture sensor and as well as its source code?what type of microcontroller did you use?what kind of program did you use?
thanks allot,your response is highly appreciated.this would help me in my thesis..
hi
can i ask you a favor to please send me one copy of the whole circuitry for moisture sensor and as well as its source code?what type of microcontroller did you use?what kind of program did you use?
thanks allot,your response is highly appreciated.this would help me in my project..
i am doing a project on an automated sprinkler system. please do reply.
i am a 3rd year electronics engineering student from india. i study in BITS Pilani goa campus.
The campus website is http://www.bits-go.ac.in
I assume the circuit is based on the probe going from an open when it is dry to some amount of resistance when it is moist. If that is the case, why not eliminate the transistor and pot and simply have a resistor divider going into an analog to digital converter pin on the micro?
What do you use for the electrodes?
The transistor is intended to amplify the very small amount of current that goes through the soil.
We have tried many different materials for the moisture probes and the best so far is stainless steel rod.
This looks quite easy. Thanks!
Trying it out I seem to get that to calibrate I need to trim the variable resistor so that it is just low enough that it does not pull the output to ground. Is that the most sensitive setting? I imagine that the transistor essentially pulls the output value up when more moisture is applied.
I would also be interested in what rod length and rod spacing you used, whether you have found any particular values to be “better” in any sense.
Tim
Rod length and spacing were not the most significant variables. In general you want the probes long enough to reach the moist soil and not so close together that they are likely to touch accidentally. Keeping them about an inch apart works great. The big variable is the composition of the soil itselfj (especially salts), so ideally you would calibrate for each type of soil.
This look interesting.
It would be nice to have a unit that had probes at several depths. A bit from the microcontroller could be used to turn on a transistor that provided the +5 to the soil (if needed).
I am thinking about housing the unit in a 4 inch PVC pipe several probes attached to determine moisture at several levels. It would be good if the probes could be attached flat on the outside of the PVC pipe. The PVC could be set into the ground with a post hole digger.
What do you think ?
Hi!
What sensor are you using?
Thanks for the info!
Roberto
Roberto, we just used two metal probes stuck into the soil.
i am doing a project on sprinkler system can u help me about this project?
can u tell me moisture sensor circuit that u have design is capable of detecting howw much area?
ur reply is appreciable.
if u have done any kind of such project please reply me on my mail id.
thanking u.