Propeller clock is major final year project in btech. We were planning this project since last semesters. Finally time has come to complete it. We are now collecting Data on it. Project is mainly depend on speed of motor. We will use DC motor for this purpose. DC motor will be 12v 100 mA 2000RPM.
Put seven LEDs on a stick and rotate them at 600 rpm, use a small microcontroller to keep the time and
blink the LEDs in an appropriate pattern to show the numbers and you have a propeller clock!
As your eye cannot follow the flash rate of the LEDs, it looks like the digital numbers are floating in thin air!
Watch a small movie (750kB) of the clock to see what it is like!
Main features of my clock are:
- Easy-to build isolated power supply with a transformer built with 40mm & 50mm PVC pipe.
- Basic PIC 16F84 flash microcontroller
- Hall sensor with permanent magnet as index sensor
- Time set possible when the clock is rotating (using a second Hall sensor with an electromagnet from a relay)
- Standard PC power supply FAN used as motor to get the clock rotating.
The first idea to create a clock like this is from Bob Blick, you can find more designs on the internet,
just use a search engine and look for “propeller clock”.
To get the propeller clock going I used a 230Vac fan (as used in PC power supplies) because it is easy to get
and it has a nice large rotating motor house to build on.
I tuned down the speed to an acceptable low level of about 600 rpm by using series capacitors (about 1µF).
The PIC is fast enough for higher speed, but the noise becomes unacceptably high at higher speeds!
The main problem with this propeller clock is how to get the power to the rotating printed circuit board.
This problem is solved by building an air-core (!) transformer with static primary and rotating secondary winding.
The air core transformer is driven by a high frequency SMPS which will be described later on.
In the drawing below you see how the rotating PCB is connected to the FAN motor:
-The Copper windings are coiled on the 40 mm secondary PVC pipe and fixed with laquer or glue
-The primary is built in the same way usinng a slightly shorter 50mm PVC pipe.
-The base plate has a hole with the same ddiameter as the static PVC pipe inner diameter
-The secondary coil is glued to the fan mootor house (be sure that it is centered well!)
-The primary is glued to the base plate wiith the hole
-The base plate is screwed to the corner hholes of the fan house.
-The rotating pcb is screwed to a small piiece of PCB which is glued on top of the rotating PVC pipe.
Then coming to the circuitry part our clock just consist of the
at89S52 microcontroller ,8 bright red led, a perforated PCB,
8 resistances (220 Ω), a photo diode, an infrared transmitter,
a motor,a pull up ladder,a 10µf cap, 12 volt battery .
The clock is on a spinning piece of pcb, but it must get power so to
give the required power a 9 volt battery is applied which works
very fine as u can see the results are super fine.
The circuit can be made either by designing the pcb or it can be
made on a zero pcb as we have done , because doing it on a zero pcb
was very much easy.Firstly a 20 pin socket for the AT89C2051 was
attatched,then connecting the power supplies leds and resistances.
The circuit is very easy as it took me only 2 hours and by evening
the clock was running.
For the leds I used the 220 ohms resisors for proper brightness.
A crystal of 11.0592 Mhz was selected to provide the clock to the
Connect the motor properly between the pcb so as to maintain the
centre of gravity so that the clock does not wobble and the display
is crystal clear.
So much done, now only thing left is programming the microcontroller.
I used the at89s52 microcontroller which belongs to the 8051
family of microcontrollers.so I used the kiel compiler to write the
The code is written in c language and the code finally burned to the
controller and the clock is running.
Micro controller 89S52
LCD display 16*2 matrix
DC motor 2000 rpm
PC817 – optocoupler
Wood or ply
Resistance 220 ohm
Capacitor 0.01 micro farad
Keyboard general or push to on Button
Microcontroller programming kit
copper clad board
8051 programmer universal kit
CRO 20 Mhz
Keil for Programming/SDCC/UMPS
Proteus 7.6 Simulation