Measuring Day Light Hours - Remote Beehive Project

The Objective:

This project was carried out to help monitor the health and well being of bees in a remote beehive location that could in theory be located almost anywhere in the world. There are a couple of different variables that we are monitoring but will only cover light in this segment.

Background Theory:

Monitoring of bee hive is not only important for the health of the bees but the health and nutrition of man kind, this is a bold statement you might say but did you know that the honey bee is responsible for 80% of all pollination worldwide. A single bee colony could pollinate 300 million flowers each day, sounds light a lot right?? but the average numbers in a healthy hive in summer could be 60,000 that works out at 5,000 flowers each per day, this is achievable as they do not spend a lot of time at each plant, i can only assume this is where the name 'busy bee' came from. The pollination process is essential for many of the foods that we eat, in fact one in every three things humans eat is in some way link through bee pollination.

Examples: Kiwifruit, Potato, Onion, Strawberry Tree, Broccoli, Cabbage and Water Mellon to name a few. There are many more which maybe found here.

Why Light:

Why is monitoring light important to the health of a bee hive?? Bees will only forage during daylight hours so the more hours of light in a day the more pollen that will be foraged and thus more honey produced. Not only is this important for bee foraging but plants also need good light among other elements for healthy growth. The only issue with an excessively sunny day is that if the temperature is too high the bees will need to return to the hive to help reduce temperature and thus less honey will be produced this element will be discussed in a different segment. Bees will also avoid leaving the hive during inclement weather so recording the light at any particular time can give an indication of weather conditions and thus potential honey production.

So what is an LDR?

A light dependent resistor (LDR) is a component whose resistance changes with a change in light intensity. When a high level of light is present its resistance will decrease usually to under 100 ohms and when low levels of light are present the resistance can increase up to a value 10M ohms.

Why are we using an LDR?

The LDR is a relatively low tech approach to light sensing and consists of a simple circuit consisting of a 1k resistor in series with the LDR to form a voltage divider circuit. The center point on the voltage divider is where the input to the Arduino is taken from. Our particular circuit we decided to add a transistor and LED to the circuit, this is in no way needed for the project to work but we felt a visual display would help with any fault finding that may be required.

The finished project actually incorporated the Arduino which displayed the LUX on our computer screen indicating whether it was day or night time and if the light levels were sufficient for bee hive productivity, as bees do not forage between dusk and dawn.

Equipment Required To Build Circuit:

1. A Breadboard
2. A 1K ohm Resistor
3. LDR
4. Arduino
5. NPN Transistor (Optional)
6. LED (Optional)

The circuit is relatively straight forward as stated previously and will be supplied with 5 VDC.

The LDR will be in series with a 1K ohm resistor to create a voltage divider. The voltage at the mid point (Vout) will be the source of measurement, the Arduino take in the analog voltage and covert is to a digital signal from 0-1023 bits. The next part is optional but we decided to use it for a visual reference:

The transistor (Collector & Emitter) and LED are connected in series then these two will also be placed in parallel with the LDR voltage divider, then the base of the transistor is connect with Vout from the LDR voltage divider circuit (the same place the input signal to the Arduino is connected) this may sound slightly complicated but when you see the circuit diagram below is is actually quite simple.

The amount of voltage dropped across the resistor is determined by the resistance value of the LDR at a particular light intensity therefore depending on light levels different voltages will then be seen and this is fundamentally how this circuit works.

Circuit Theory:

Current in a series circuit is common to all parts and when light intensity changes the LDR resistance changes. We also know that ohms law states that V=IR so when resistance changes the voltage dropped across that resistor will also change and this change is voltage is how the measurement is taken.

Vout can be determined due to the voltage divider formula.

Vout = Vin (LDR / R1+LDR)

A scaling Arduino code will also be required to convert the voltage (Vin) back to a readable value in LUX.

The arduino is a handy little prototyping device for small projects such as this, if you are unfamiliar with this device i highly recommend visiting some of the tutorials on youtube i found them extremely helpful to learn coding.

The device basically works by taking an analog input such as the voltage output from our voltage divider and turns it into digital bits from 0-1023. There are of course other platforms available such as the raspberry pi but we found the Arduino was most suitable for this particular project.

The following Arduino code puts out a display stating whether or not it is day or night time.

We decided to go further with this code and so when the LDR was sensing dusk/dawn illumination ie. below 400 LUX the code would print out night time and when the LUX rise above 400 it would print day time, from this information we can correlate data over a period of time to assess if the position/location of the hive is ideal and get an indication how much light we are receiving daily.

It may not be apparent with just one variable but once the other instrumentation is integrated we can get a good understanding of the environment the hive is located in.

Lux is the SI unit of measurement for illuminance. This will be our indication of how bright it is near the beehive.

If our light sensing system is completely accurate, at 22,000 LUX (bright sunny day) we should see 1023 bits and if we could get down to zero LUX we should see 0 bits, although we would like this level of accuracy it is not really that essential as the bees dont really care if it is 10,000 LUX or 11,000 LUX the real issue is when it gets down to dusk/dawn levels when they are unable to fly therefore we decided to keep the code as simple as we could and print out whether it is brighter than dusk or dawn and for how many hours.

Time could be spent upgrading the system so it's a lot more accurate by rescaling the nonlinear system which would involve taking the slope of the line and log to create a relatively straight line it but for beehive monitoring purposes there would be no real advantage.

This is as far as we will be going in terms of this element of beehive monitoring but in time when we have temperature, humidity and rainfall to add and with these four elements combined we would have a good overall view of the environment the beehive is located in, over time we can correlate the data and use this information to create an overall idea of the health and well being of the environment and the beehive itself.

Thanks for reading.