A simple and convenient scheme for assembling a propeller watch. Clock propeller It's time to start

Remember those? Some time ago they conquered the Internet. It turns out it's pretty common. See how you can make them yourself...

These funny electro-optical watch create the illusion that the numbers are hanging right in the air.

A rapidly rotating strip of seven LEDs is illuminated at certain points in time, from which there is an optical effect that there is a discrete scoreboard measuring seven by thirty dots in front of your eyes. How do they work watch propeller?

A small circuit board is mounted on the motor shaft, on which the electronic filling and seven LEDs are assembled vertically. When rotating rapidly, any point source of light is perceived by a person as a continuous band of light. The microprocessor, in accordance with the programmed program, modulates (turns on and off) the illumination of each LED in time so that there is an effect of displaying numbers that seem to be suspended in the air, since the board itself flashes so fast that the eye is not able to track its movement . A similar effect is used, for example, in a cathode ray tube, where at certain moments a signal is applied to a continuously scanning electron beam screen.

To download the original image from the author of the clock-propeller scheme

Design:

The clock is assembled on a small circuit board. This board with components and LEDs rotates on the motor shaft. The question arises of how to supply energy to the board? Various options have been considered to solve this problem. Firstly, two motors can be used: one main, rotating the circuit, and the second, located on its shaft, operating in generator mode. You can also use a rotating transformer or slip rings. However, a more convenient way is to remove voltage from the rotor windings of the main motor. To do this, you need to subject the engine to a little refinement: remove the bearing from one side of the shaft, leaving a hole free through which you can pass the wires.

Inside the motor there are three windings through which an alternating current flows, shifted in phase by 120 °. To the ends of these windings, you need to solder wires, which are then connected to a three-phase rectifier on the board to get direct current again. The advantages of this method include the fact that at the same time it is possible to control the position of the motor shaft if one phase is connected to the measuring input of the microcontroller.

Improvement of the electric motor:

Take an unused rotary head motor from a Sharp or Samsung VCR. The motor used in this project is marked JPA1B01, but according to the data sheet it is called RMOTV1007GEZZ. Carefully remove the brushes (through the small holes in the housing). Please note that the rotor is fixed at one end in a ball bearing, and at the other end rests against a cover with a plain bearing, which must be removed. Glue or solder it on top of the ball bearing axle (on the other side) to reinforce the shaft. Adjust the height of the axle by holding it in a vise and lightly tapping it. Solder the three wires to the three mounting pads on the motor rotor. Glue a small threaded bushing to the axle on the side where it comes out of the hole, fasten the conductors under it and assemble the motor. For greater structural stability, you can glue this motor to the video head unit.

Mounting of electronic components:

Clock components are soldered to a circuit board with plated holes. The outputs are connected by conductors. An 18-pin socket must be installed under the 16C84 microprocessor, since it is programmed in a separate programmer. Under the seven load resistors R1B.R1H, it is convenient to use the appropriate DIP resistor matrix, which will allow you to experiment with the brightness of the LEDs. Discrete 120 ohm resistors can also be used. They work fine, albeit at the 16C84 surge current limit. Think in advance how you will balance this board so that there is room for this on it. You can replace components with others with similar characteristics. The author used a 47,000 uF ultra-capacitive storage capacitor in the circuit so that the clock would not be reset after the engine power was turned off during correction and time setting. You can use a 0.47 uF ionistor instead. Remember only that the LEDs must be powered bypassing it. A ceramic resonator should be used only for a frequency of 4 MHz, since the accuracy of the clock depends on it (or if a resonator for a different frequency is used, the program must be modified accordingly).

Programming 16S84

To program the 16C84 microcontroller, you can use any programmer available for this. The site contains a binary firmware file (download). Assembly language source code can be found. When programming, be sure to set the following options: wathdog timer (WDT) - OFF, resonator. normal XT-crystal.

Final assembly and timing:

Fix the board with parts and LEDs on the motor shaft. Solder three power wires. Apply voltage to the motor. The nominal voltage is 6.2 V, but you can change it between 5 V and 7.5 V. You only need to take into account that due to the drop in the rectifier diodes, the 5 V voltage on the board corresponds to the motor supply voltage of 6.2 V. After applying voltage, the clock should show 12:00. If this is not the case, then perhaps the fact is that the storage capacitor has not completely discharged. Turn off the power and briefly short pins 4 and 5 together to reset the microcontroller. After that, you can turn on the power again, make sure that the clock is working, turn off the power and set the exact time using the "Hours", "Tens of minutes", "Minutes" buttons. If the numbers are displayed backwards, reverse the voltage polarity on the motor. You can experiment with balancing the board, putting foam under the motor base to reduce vibration, etc.

With diagrams. and you get something like this:

Here's another option.

Many outlandish electronic projects can be found on the Internet, which does not give rest to the inquisitive mind.
And although the “propeller clock” is far from a novelty on the big Web, I, having stumbled at one fine moment on a clock circuit with a stroboscopic effect, could not pass by.

A bit of theory

The main idea of ​​the device is microcontroller control of a group of LEDs mounted on a rapidly rotating base.

The code defines a loop that repeats from an external interrupt. Let's say the length of the total burst is 15 ms. During this period of time, each LED lights up n-number of times. At a low rotational speed, the human eye will catch only a single inclusion of all the LEDs at once. But, it is worth increasing the frequency of rotation, and small intervals of the common pack will begin to stretch along the X axis, and the eye will already begin to catch non-simultaneous responses. This will continue until a certain limiting frequency of rotation, at which an interval of 15 ms will be expanded to a certain length along the X axis, at which the blinking intervals within the common pack will already be clearly distinguishable and numbers will be drawn that will add up to the overall picture. A further increase in the rotational speed will lead to a stretching of the total burst of pulses and the numbers will become unreadable.

The board was redesigned for SMD components, because the smaller the weight of the board, the lower the load on the fan.

The rotating part consists of a main board and an indication board on which the LEDs are mounted.

I used SS12 Schottky diodes as rectifier diodes. I soldered an 18-pin socket under the microcontroller, since a “idle start” was needed.

The length of the arm can be adjusted to taste, taking into account the comfortable observation of the luminous part. In my opinion, a 90-110 degree sweep is optimal. The scan option less than 90 degrees will bring the numbers together, and more than 110 degrees will stretch the image too much in diameter.

Initially, I chose a shoulder length of 65 mm, but the experience was unsuccessful and I sawed off the finished board to 45 mm.

The board with LEDs looks like this.

It has 7 main LEDs and 2 backlight LEDs. All LEDs are 5mm in diameter.

The connections of the two boards are made by soldering the connecting pads. I etched the boards, carried out the installation, connected them. Now you need to put them on the fan rotor.
To do this, I drilled 3 holes with a spread of 120 degrees.

I inserted screws with a countersunk head with a diameter of 3 mm and a length of 20 mm into them. I fixed it on the nuts and fixed the boards on them.

Soldered the ends of the secondary winding to the board. On the opposite side of the display board, I put a compensating counterweight to reduce the beating during rotation.

The time has come for an idle run without a microcontroller. I put the rotor with the boards in its place on the fan and applied power to the RF generator, the fan is still motionless. The backlight LEDs light up. I checked the voltage at the input, it sank to 10 volts, this is normal. It remains to install a synchronizing optocoupler, consisting of an infrared photodiode and an infrared LED. I glued the IR LED to the base of the fan and powered it from the main +12 V power supply through a 470 Ohm resistor. I soldered an ordinary IR photodiode on the board.
I installed the optocoupler so that during rotation the photodiode flew over the LED as close as possible.

I programmed.
I installed the controller in the socket, secured the rotor with a retaining ring.

It's time to launch!

The first inclusion and pleased and upset at the same time. The circuit worked, the LEDs gave out the time 12:00, as they should, but the image was blurry along the X axis. I started the “debriefing”, as a result, I came to the conclusion that it was necessary to replace the photodiode. The spread of the operation area from the external interruption of the MK turned out to be too large.

I decided to put a photodiode with a narrower radiation pattern, and also glued the LED with black electrical tape.

The response area decreased 2-3 times, and the subsequent inclusion pleased: the blur completely disappeared.

I note again that low-power fans will not accelerate this design to the desired speed, and the picture will flicker in your eyes. I redid the project three times, and only the option on the fan with parameters of 0.4 A; 4.8W; 3200 rpm worked great.

An obvious disadvantage of the design is the lack of a backup battery for the controller. Yes, yes, the time will be reset each time the main + 12V power is removed.

And so, for the manufacture of Propeller watches, we need the following parts:
For watch:

* Driver LED MBI5170CD(SOP16, 8 bit) - 4 pieces.
* Real time clock DS1307Z/ZN(SMD, SO8) - 1 piece.
* Microcontroller ATmega32-16AU (32K Flash, TQFP44, 16MH) - 1 piece.
* Quartz resonators 16MHz - 1 piece.
* Quartz resonators 32kHz - 1 piece.

* Resistor 100nF (0603 SMD) - 6 pieces.
* Ker. capacitor 22pF (0603 SMD) - 2 pieces.
* Ker. capacitor 10mF * 10v (0603 SMD) - 2 pieces.
* Resistor 10kOm (0603 SMD) - 5 pieces.
* Resistor 200Om (0603 SMD) - 1 piece.
* Resistor 270Om (0603 SMD) - 1 piece.
* Resistor 2kOm (0603 SMD) - 4 pieces.
* Still needed: watch battery, holder for it, IR LED, IR transistor, LEDs (0850) 33 pieces (one of them (the last one) can be of a different color)

For motor driver:

* TDA5140A motor driver - 1 piece.
* Linear stabilizer 78M05CDT - 1 piece.
* Ker. capacitor 100 mF polar (0603 SMD) - 1 piece.
* Ker. capacitor 100 nF (0603 SMD) - 1 piece.
* Ker. capacitor 10 mF polar (0603 SMD) - 2 pieces.
* Ker. capacitor 10 nF (0603 SMD) - 1 piece.
* Ker. capacitor 220 nF (0603 SMD) - 1 piece.
* 20 ta - 2 pieces.
* Resistor 10 kOm (0603 SMD) - 1 piece.

Hi all! I want to bring to your attention a simple propeller clock that I assembled on the Atmega8 controller. They are made from affordable parts and are easy to replicate and make. The only thing is that you need a programmer to flash the clock controller and the control panel.

A conventional 120 mm fan (cooler) was used to base the clock. You can use any fans for this watch, both with clockwise and counterclockwise rotation, because while I was collecting this watch, I redid the program a little and switched the display of symbols from the remote control programmatically.
The circuit of the watch itself is quite simple and is assembled on the Atmega8 microcontroller, for the synchronization of which clock quartz with a frequency of 32768 Hz is used.
The clock is powered by a receiving coil, energy to which is transferred from a generator with a transmitting coil. Both of these coils make up an air transformer.

With the scheme and design of the generator, there were no special problems, since a generator from a plasma ball was used.

The generator is assembled on a common TL494 chip and allows you to change the width and frequency of the output pulses over a wide range.
Even with a gap of a centimeter between the coils, the voltage is enough to start the clock. It should only be taken into account that the larger the gap between the coils, the greater the pulse width needs to be made and, accordingly, the current consumption from the source also increases.

When you turn on the generator for the first time, set the pulse width (duty cycle) to a minimum (the regulator knob is in the upper position according to the diagram, that is, the 4th leg through the resistor R7 is pulled to the 14th, 15th, 2nd leg of the TL-494). We twist the frequency of the generator until the squeak disappears, this is approximately 18-20 KHz (tuning by ear), and if there is something to measure the frequency, then we adjust it accordingly within these limits.
On the generator board, a voltage regulator on the LM317 is additionally assembled, designed to adjust the fan speed.
It is not on the diagram, I did not finish it
. Watch a demo video of the watch in action.

Video.

The clock board itself is attached to the base of the fan. I secured it with double sided tape.

Then I redid the clock circuit a little from a photoresistor to an infrared photodiode (figure below).
In the transmitter, instead of a simple LED, I now have infrared.
The resistor instead of 2k put 100k.

Responsible moments in the manufacture of clocks are the manufacture of an air transformer and the alignment (or rather balancing) of the clock board on the base of the fan.

Take these moments seriously.

Air transformer.

I took a regular 120 mm cooler with bronze bushings as the basis. The clock board is glued to the base with double-sided tape.
We bite off the blades from the cooler and grind and level with a file, sandpaper. Coils are made on a frame from a cable channel. I did not come up with such a design, I just took this idea from the Internet. For winding the transformer, a base is made from a cable channel. Every 5 mm, we make an incision on the sides of the channel and carefully fold it into a circle, select the diameter so that it fits snugly on the plastic base of the fan.

Next, on the mandrel from the cable channel, we wind 100 turns of enameled wire, with a diameter of 0.25.
The current consumption of the assembled transformer, I got 200 mA (this is with a rather noticeable gap between the coils).
In general, together with the fan motor, the current consumption is obtained in the region of 0.4-0.5A.
We also make the primary (transmitting) coil, but we try to make the minimum gap between the coils. The transmitting coil also contains 100 turns of wire 0.3 (you can use the same 0.25).
In the diagram, I have slightly different winding data for these coils.

Hours pay.

The bar with LEDs is made on fiberglass. A hole is drilled in it, a piece of tube from a telescopic antenna is inserted into this hole and soldered to the board (the antenna tube must be cleaned from the shiny coating). You can use any suitable tube, or attach the board in another way, for example, using a screw with nuts.
I connected the board with LEDs to the clock board with an ordinary enamelled (winding) wire, it is more rigid compared to the mounting one and does not fray during rotation.

To balance the entire board, on the other side of it, we glue a screw with a diameter of 3-4 mm with hot glue, screwing various nuts onto the screw on the other side - we achieve minimal vibration.
To check the performance of the clock board - we shorten the photoresistor with a screwdriver, tweezers, while the LEDs should blink.
The clock starts working when 5V (logical unit) appears on the 5th leg of the atmega. That is, when the photoresistor is illuminated, there should be 5V on the 5th leg,
When the photoresistor is not illuminated, there should be a logical 0 (about 0V) on the 5th leg of the atmega, for this we select a resistor to the ground from the 5th leg. The diagram is 2 kOhm, I got 2.5 kOhm.
At the bottom, on the base of the fan, we glue the LED so that with each revolution of the fan motor, the photoresistor passes as close as possible to the light source (LED).

Remote Control.

The control panel is designed to control the operation of the clock, switch display modes by indication (change the direction of rotation of the fan), set the clock time.

The remote control circuit is assembled on an ATTINY2313 microcontroller. On the board, the MK itself is installed with a strapping and six buttons designed to control the clock.

I did not assemble the case for the remote control, so only a photo of the board itself.

Information on the purpose of the remote control buttons;
H+ and H- clock setting
M+ and M- minutes setting
R/L direction change (for clockwise and counterclockwise screws)
font font change (thin, bold and inscription website)
when labeling the site with the H + and H buttons - the width of the label is adjusted.

The attached archive contains all the necessary files for assembling the watch;

Archive for article

If you have any questions about the watch design, ask them on the forum, I will try to help and answer your questions as much as possible.

Finally, he realized his old dream - he made a propeller watch! I got this idea on fire a few years ago when I saw the work of this watch on You Tube.
The implementation of the idea was complicated by the fact that all the schemes, and there are just a lot of them on the Internet, are implemented on PIC controllers, and I still have not been able to flash it. I tried a bunch of programmers, but either my hands were crooked, or the stars stood up at that time, but all my attempts were unsuccessful. And I did not find any circuits on Atmel microcontrollers, with programming of which I have no problems. I tried to encourage familiar programmers to write a program for the AVR, but did not find a response in their souls. Maybe the idea would have remained buried under the rubble of a collapsed hope, but recently I began to look through my collection of various circuits on disks that I bought at a flea market ...

small update . The clock made above proved difficult for our readers to repeat. Therefore, a simplified version was made, without the use of machines. Detailed