Date: Monday, November 04 @ 04:48:41 EST
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.
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.
I've used a high Japanese adhesive for the mountage of parts. is the most suitable glue for building this kind
of robot bugs and robot flowers. The glue cures in a very short time and holds the plastic pieces together very firmly giving the parts the ability to carry heavy loads. Usually it is impossible to separate any two piece glued with this kind of adhessive without damaging them. So, care must be taken.
The flower turns its DC motor forward or backwards by comparing the voltage level that comes from the two light sensitive transistors on each front side of its face.
The simple circuit which consists of only 4 transistors and 4 resistors performs the comparation. When the light level falling on top of these two transistors are nearly equal, the flower either stops turning or begins resonating with small steps facing towards the same direction; The sun.
Especially it is really funny to watch the sunflower robot following a 100W lamp turned around it by hand. It follows the lamp so fast.
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.
Continued with the simple circuit schematic.
Don't forget to test the circuit on a testboard before soldering it.
This is my second sunflower with improved mechanics. By using two gears i've made a better light follower.
This is an other sunflower. The circuitry is the same but the transistors are replaced with more powerful BD135 and 136s. Photodiodes are also used as parallel to be able to give more driving power to the transistors; each photodiode on the circuit is constructed by paralleling two photodiodes.( So, in total 4 photodiodes are used).
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.