YS27-3 fluorescent clock (verified)

Fluorescent tubes are electronic components that were widely used in the 1990s. Its driving voltage is lower than that of Nixie tubes, and its lifespan is longer than that of Nixie tubes. It no longer requires a 10-layer cathode digital arrangement, but uses modern The 7-segment digital display is arranged, and the display color is mostly blue-green, which is common in fluorescent materials. Therefore, it does not look as retro as a Nixie tube, but it is still a type of electron tube.
 
YS27-3 is currently the cheapest fluorescent tube made in China. It was made by the state-owned electronic tube factory in imitation of the Soviet manufacturer IV-22. The price in the seafood market ranges from 9 to 20 yuan. It is a good experience to spend a hundred and ten yuan to make a retro industrial clock from the last century. This project was made at the end of last year, and I haven’t had time to sort out the relevant information. This clock is very simple to make, and there is a large stock of YS27 on the market.
 
Let’s briefly talk about the design of this project: the
 
selection of components .
 
The boost component uses MT3608 as a 20V boost IC. This chip supports 2-24V input voltage, the output voltage is up to 28V, and has current limiting and thermal overload protection.
Select RT8059 as the voltage-reducing component, and the required voltage can be adjusted through different resistance values.



 
The output calculation formula of this IC is:
Vout = Vref x (1 + R1/R2)
 
The driving component uses 74HC595D + TD627838 to control the filament on and off, which will not be described here.



 


PCB design


 


PCB design adopts upper and lower plug-in board structure. The upper layer is the socket part of the fluorescent digital tube, and the signal and power supply are plugged into the lower PCB using row pins; the lower PCB is the power supply, driver and control board of the clock. The power supply uses a micro usb interface (it can also be changed to a Typc-C interface). The PCB uses a 1.6mm board thickness. Due to limited space, the upper PCB is not designed according to the regular sequence of each stroke of the segment code. Instead, the connections are based on the principle of convenience. This can be adjusted later through the program. Implement the lighting sequence of segment codes. The lower PCB arranges the components in scanning order.
 
The programming
 
 


program is developed using arduino IDE, and the program uses the ShiftRegister74HC595 library. This library can control the 74HC595 shift register in a very simple way. In our design, four 74HC595s are used in series. A single 74HC595 has 8 driver pins, and 4 in series are 32 pins.
 
 


According to the correspondence between the filament pins and the driver in the schematic diagram, we can see that the 1 to 8 pins of the 74HC595 (corresponding to 0-7 in the program) correspond to the filament pins in order of 5, 6, 8, and 1 respectively. ,2,4,3,7. Then from the following filament arrangement, we can design several arrays to control which number is displayed:
 
 


for example, displaying the number 0, pins 3 and 7 (the numbers in the program start from 0, corresponding to 2 and 6) correspond to low level, other pins correspond to high level, then the corresponding relationship in the array is:
 

filament pin


1


2


3


4


5


6


7


8


corresponds to array


0   


0


1


0


0


0


1


0.

 
Use the relevant function of ShiftRegister74HC595 to control the corresponding pin The correct number can be lit up by adjusting the level.
The following is the definition array:
 


//Create an array corresponding to the digital filament int Numbers[10][8] = { {1, 1, 0, 1, 1, 1, 0, 1},//0 {0, 1, 0, 1, 0, 0, 0, 0},//1 {1, 0, 0, 1, 1, 0, 1, 1},//2 {1, 1, 0, 1, 1, 0, 1, 0},//3 {0, 1, 0, 1, 0, 1, 1, 0},//4 {1, 1, 0, 0, 1, 1, 1, 0},//5 {1 , 1, 0, 0, 1, 1, 1, 1},//6 {0, 1, 0, 1, 1, 0, 0, 0},//7 {1, 1, 0, 1, 1 , 1, 1, 1},//8 {1, 1, 0, 1, 1, 1, 1, 0},//9}; Please
 
 
refer to the source code for the specific implementation method. In addition: the network configuration method has been written in the program comments, and the lighting effects and second hand color can also be defined by yourself. It is very simple to use WS2812FX. It's a human-made program, and the source code is not well organized, so it can probably be used. Please refer to the figure above for the specific assembly structure of
 
the shell design . There is no difficulty in welding this project. It has been verified and can be safely welded. The program and shell files are in the attachment. If you have any questions, you can ask in the group 839867934.