Introduction: Robotic Solar Powered Sunflower

Picture of Robotic Solar Powered Sunflower

Our sunflower is a tiny robot flower which has no mobility. It can only and continuously turns its face towards the sun like the sunflowers do.

Step 1: Parts

Picture of Parts

The robot sunflower is made from plastic parts taken from old CD drivers and junk home equipment; a small dc motor and reduction gear from the CD-R sawed together with some plastic parts, a tiny solar panel, some other plastic parts taken from an old aquarium filter and a simple, 4 transistor circuit made by me.

Our flowers uses the energy that comes from the sun to find more sunlight. So it continuously turns its face (the solar panel) towards the sun. As the same way sunflowers do. You can put it at balcony or window ledge. I've glued a magnetiesed CD holder disk taken from the old CD-ROM driver to the base of the robot. So when it is put on to a mettallic surface, it holds the surface firmly by the use of magnetic force.

Step 2: Where Can You Use?

Picture of Where Can You Use?

anywhere it sees light. it will turn towards the sun with no need of external power.

if you use it inside your car, then every turn will affect its direction though it will simply follow the sun turning around the car.

The best way of making the mechanical assembly is as follows. The motor is mounted upside-down, the axle is connected to a magnet which will be used as the base of the flower, enabling it to firmly stick to any magnetic metal surface. Though the circuitry and the power supply (the solar panel) will be mounted on top of the motor, there will be no cables which are connected to the outside world, disabling the 360° turn of the flower.


sciencefair9 (author)2014-01-07

Can someone give me a list of the materials, I am doing this project for science fair

colin55 (author)2013-04-07

This circuit is a very bad design. The transistors produce a short-circuit across the power rail.

Cyborg2004 (author)2011-03-27

Your site is still down. Google said your site contains harmful and/or malware software.

arduino man (author)2010-12-18

My computer says that to.

hobbyman (author)arduino man2010-12-19

checked it out and didnt see any problems.

sniper69jr (author)2010-03-02

Is there away this can track the sun and charge a battery or power a device.

hobbyman (author)sniper69jr2010-10-06


gregario (author)2010-03-03

Hi, This is brilliant! Thanks...

Am looking to build one myself but am having trouble with the motor from the cd drive, any chance would you have more details for me to work with? Or would there be a similar low voltage motor I could buy that could work on the cheap?

hobbyman (author)gregario2010-10-06

any low current, miniature DC motor should work.

aenhya (author)2010-05-31

I would like to use it in a project, with a bigger motor to drive a bigger solar panel.
Witch power transitors can i use ?

Gtrz Aenhya

hobbyman (author)aenhya2010-10-06

any complementary power transistors or darlingtons which are powerful enough to drive your DC motor can be used. Consult to the datasheets of the motor and choose transistors accordingly.

RPisces (author)2007-07-18

I Made one of these, but all it does is spin continuously in one direction. HELP!!!!

buteman (author)RPisces2010-02-10

I know this is very late, I only recently joined this site.
This is one of the things I have been looking for.

Added this comment in case someone else has the same problem.

You probably have the wires from the motor connected the wrong way round.

Just swap them over.

buteman (author)2010-02-10

The transistors need to be able to supply the current the motor needs.
The spec for the BC550 Hobbyman used is here :|13123|bc550||S|e|3858133029
and the BC557 is here :

Sorry the links are so long.

You can choose almost any transistor which can handle the same or higher collector/emitter voltage  ( Vce ) and the same or higher collector current ( Ic ).

hobbyman (author)2009-08-05

u can see thm in the circuit schematic. actually I dont remember now :)

Dan-Technician (author)2009-03-28

You know the symbol (image): What does this mean? Is it just connected to the LO current (0v)? Can you please explain this symbol, I see it everywhere but I don't know what it is? Thanks in advance, Dan

bangstick (author)Dan-Technician2009-04-06

Dan, This means "Ground" or "Earth". In a small robot like this that is not hooked up to a wall socket it means the negative side of the Battery. Although this is technically not the correct use of the symbol, thats what most people take it to be. Sometimes just to confuse things people will also use "0v". The correct usage of this symbol should only be used when tied to a chassis that is earthed either through a mains or directly into the ground.

bythenumbers (author)bangstick2009-07-10

the whole idea of a "ground" is a reference voltage. So if you want a 5V difference across a given set of terminals, you can hook one end to +5V and the other to a real ground, 0V. You can also create a "virtual ground" by hooking the terminals to opposite ends of a 5V battery of some kind. The negative terminal may not necessarily be 0V, but it's 5V less than the positive terminal, and that's all that counts. I, below, is the first case, where A is at a definite +5V and B is a true ground. II shows the presence of the same 5V difference, but no "reference voltage", no connection to ground. Thus, nobody can say for sure what voltage A or B is at relative to ground. However, A is 5V above B, regardless. Many times, people will just set B to a "virtual ground" and treat it as if it is at 0V, just to make life easier, (and because it's correct in most applications) even though it's not technically (or always) correct. Just trying to be textbook in the definition and use of "ground".

Dan-Technician (author)bangstick2009-05-26


sk74 (author)2008-11-16

Hi, It is amazing and looks good in your provided movie, for small panels it is ok but can we make it for large panels i.e. 300W systems? I think we have to build system by large components but can you tell me what are the possibilities and have any idea regarding substitute materials?

forjefftoread (author)2008-09-11

Super cool! but I don't understand the electronics layout. Do you have a detailed schematic?

Nevermind... found the schematic.

PocketSized (author)2007-05-08

Here is the one I quickly made.
The Parts
2 x NPN transistors: 3904 (They were all that I could find)
2 x PNP transistors: 9015 (They were all that I could find)
2 x 1.5v AAA batteries (I had no solar cells)

It works rather well, although I'm sure using the correct components would make it function more efficiently.

kk khrab (author)PocketSized2008-07-08

can you plz send me this things circuit. If yers thanks it will be nice of you

PocketSized (author)kk khrab2008-08-20

The schematic is exactly the same as the one given by Hobbyman in Step 1.

Except for the + and - points run off to two 1.5v AAA batteries.

reilic (author)PocketSized2008-08-20

can you show me your schematic diagram and wiring diagram of your creation kindly please

hobbyman (author)PocketSized2007-05-08

hey thats nice. i get so happy to see your version of the robot sunflower. come on and visit my robotics site at which is full of over a 100 free robot projects. ;)

PocketSized (author)hobbyman2007-05-08

That looks like a cool site; I'll have a look around it when I have some free time. I love these little projects, I'm hopeless with electronics, but that doesn't stop me from working through a project from time to time. Can you suggest any small projects like this one on

hobbyman (author)PocketSized2007-05-09

yes sure, visit our projects archive. older projects are usually simpler ones. in time as our robots evolve, projects also became more complex, with bigger circuitry, microprocessors etc.

X-mind (author)2007-07-10

does this thing turn both the ways?If yes please inform me about it.

hobbyman (author)X-mind2007-07-11

yes sure it turns both ways.

kk khrab (author)hobbyman2008-07-08

oi MR hobby man r u indian cause u look like one tell me some thimg about you

budsiskos (author)2008-06-22

what voltage does your solar panel produce?

hobbyman (author)budsiskos2008-06-22

it produces a 200mA short circuit current and its unloaded voltage is 1.6-1.8v

budsiskos (author)2008-06-20

could photoresistors work?

hobbyman (author)budsiskos2008-06-20

yes, they might work but u need to find matching pairs

budsiskos (author)2008-06-20

are all four transistors npn or pnp or mixed?

Xellers (author)2008-04-23

Would the light sensing parts from an old wheel mouse work in this project?

iovitanc (author)2007-11-05

can you upload a clearer photo with the electrical components already soldered? what should be the technical data to ask for when buying those 2 photodiodes/phototransistors?

silver912targa (author)2007-10-21

Exactly what I'm looking for. Unfortunately it is explaind to difficult. Could you please get into more details. Thanks. Michel Portugal

kishida (author)2007-09-19

Neat project. I'd like to try it soon! Thanks.

danous (author)2007-08-30

Can you please post the exact steps of the construction process of the project?

X-mind (author)2007-07-09

How would it be if I us use IR receivers(Phototransistor)replacing the photodiode ,use batteries and finally make some arrangement of the IR lightind source?Will it work?

hobbyman (author)X-mind2007-07-11

a normal photodiode is capable of receiving IR light too. So the simple circuit presented here works with IR light too.

hey do I need to use photodiodes or will photoresistors work? they conduct both ways.

X-mind (author)2007-07-13

If photodiods,then why not the motion sensors heat seekers and all those other sensors.won't it work?

that would work too.

X-mind (author)2007-07-12

Thanks for your answers.can't I use phototransistors so as to make it turn its face only when it detects IR LIGHT.Anyways its a cool project for me to deal with and once again I thank u. And ya.I had gone through the website u've mentioned.Itz cool...

X-mind (author)2007-07-09

you've used the photodiods.This means it can sense almost all visible light,not just the sunlight.If the batteries used instead of the solar cell,it continuously turns towards the light source.Isn't it?

hobbyman (author)X-mind2007-07-11

you can use a battery set instead of the solar panel. Given that the motor is able to carry the battery load, it turns toward the light in the same manner.

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