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IN-12A
D e s c r i p t i o n
Nixies is made in USSR. New, old stock. Rare, not produce now
IN-12 isThe cold cathode of these devices
has the form of Arabic numbers from 0 to 9
This listing is for
4 x IN-12A
+ 4 x SOCETS
+ 4 x Drivers K155ID1
Tube size: 19mm x 55mm (0.76” x 2.2”)
Symbol height: 18mm (0.72”)
Supply voltage: 170V
Working current: 2.5mA
Electrical parameters
| Brightness |
>=100cd/m^2 |
| Angle of visibility |
>= 90 deg |
| Power supply voltage |
>= 200 V |
| Discharge appearance voltage |
<= 170 V |
| Discharge voltage: |
<= 150 V |
| Display current |
<= 4 mA |
| Operations current: Running from DC |
4 - 7 mA |
| Running from AC with 50 Hz (average value) |
2 - 4 mA |
| Life time |
>= 5000 hours |
The clock on the discharge indicator IN-12
Previously, these indicators are widely used for displaying digital information in measuring instruments, etc., but now the urgency of this decision is questionable, however, studied an appropriate topic of our forum and ran according to the links in it, was made a willful decision to pile on the basis of the monk watches ... What, in your spare time from the basic lessons, and it was slowly realized.
Some sort of structural scheme of the device shown in the picture:
In the diagram, the red arrows show the data bus, and blue - power supply units.
Hours can be powered from several independent sources, which are isolated by using Schottky diodes with a low drop-D1-D6. As an input to the first power supply is installed MOLEX connector that allows you to use a computer power supply, the second input is designed as a conventional coaxial DC / DC jack, and the third source is the AC / DC converter circuit is courtesy of my colleague (unfortunately, it does not registered on the forum) and is presented below:
he scheme is simple, but there are nuances: a diode VD1 - fast (if you use the chip IR2153D it is not required), suppressor VD4 and VD15 are necessary to protect the rectifier diodes, if they are selected without a large supply of voltage. Transformer Tp2 made three put together ferrite rings size 20h12h6 2000NN: primary winding contains 70 turns of 0.3mm, low-power secondary winding (for supply IR2153) - 2 sections of 7 turns of the same wire (two wires dangle, then the beginning of one wire is connected with the end of the other and get the average point - as usual), a powerful secondary winding - 2 Section 7 turns of three wires braid 0.5mm (6 wires shakes, then divide in half, etc. - as well as with low-power). Do not forget the interlayer insulation!
Radiators for transistors for power to 15-17 watts is required, though the board provides a place for them. Resistor R1 represents three series-connected resistor to 100k each.
Input filter: TP1 and capacitors C1 and C2 - is taken as is from the ATX power supply, inductor L3 is wound on the ring of the output inductor of the same power supply (simply wrapped wire MGTF in a single layer - much climbed, but can be up and ready again to take .. .)
For definiteness, assume that after the diode junction voltage is 12V.
For the digital supply voltage must be 5V clock, which is obtained from the 12V with a pulsed DC / DC converter, which was built based on the chip TL2575-05 from Texas Instr.:
To supply the gas-discharge indicators require a high voltage source of the order of 200V needed for ignition and maintain a stable level in the indicator. Upconverter 12 -> 200V is made on a chip MAX1771:
In the high-voltage part of the circuit elements should be used to withstand appropriate voltage. Divider formed by resistors R2, R3 and variable resistor sets the output voltage, which can be adjusted within certain limits. In my case, the output voltage is 190V, which is sufficient for the indicators. Inverter power is sufficient for simultaneous operation of all six indicators.
I advise you to be careful when debugging: 200V - high voltage, and even isolation from the mains is present, and the power converter is not great, he was pounding on the paws quite well ...
Structurally, these DC / DC converters to save space and for a number of other considerations presented in the form of individual vertical circuit boards and soldered to the motherboard clock:
On the left - a 5-volt converter to the right - increases.
The decoder is used to convert the data stream it receives from the MC, to a form suitable for display on the display. The scheme of the decoder along with the display shown in the figure:
To display data on the display are loaded in four series-connected 74NS595 register. In the last register in the chain store data corresponding to the decimal point of the display, its output is directly controlled high-voltage switches Q1-Q6, which, in turn, ignite or extinguish the appropriate decimal point.
Younger 4 digits of the other three registers contain the binary code that corresponds to the odd character cells display (1, 3, 5), and senior nibbles - even (2, 4, 6). This code is supplied to the inputs of the binary-decimal decoder with a high yield K155ID1 that control directly to the indicators. In the plate circuit of each indicator is set current-limiting resistor. Since the current is much smaller than the current point of any of the digits of the indicator in the chain of reservoirs "point" of transistors installed additional resistors. Thus, because the register is only updated by the team manager of MK and changes occur only on certain lines of data, we have actually a static display, although the update of the display is 20 times per second.
The block itself consists of the microcontroller MC, real-time clock M41T80M6 from STMicroelectronics, USB FT232BM module for communication with a PC drive level RS-232 interface chip MAX232 for the same purpose, and control buttons. The scheme of all this happiness, as usual, is shown in Fig.
USB module to the FT232BM is a separate fee, vertically soldered into the main. Module is assembled on the template except for the missing chip EEPROM:
At the same time can only run one of the COM interfaces or USB, with preference given to USB, because switching is realized by means of the relay, energized from the connector USB: sticking with cable relay will spread and go to the controller data from the module FT232.
Generally, the interface converter USB <-> RS232 can be found in this article, and tell you a secret that in the final version of the clock is a converter on the TUSB3410, but it has been said about the priorities of interfaces is true for him ..
Structurally, the building designed in hours on the computer CD-ROM and consist, as already noted, several of the boards. The whole area of the body is the main circuit board that is mounted inside the housing to regular seats, the rest of the "native" card CD-ROM. It installed a network power supply, a microcontroller with a clock, all necessary connectors and a part of the decoder chip. The rest of the decoder chip mounted on a separate board that is installed on the main board, second floor. The power modules vertically soldered to the main board.
The back panel connectors are installed between the 4 buttons that serve to adjust the hours and mode selection.
This is how it all vygyadelo during debugging:
It is connected only to additional charges decoder, the main board yet.
Fully assembled board clock:
Thus, the constructs with little understood, now a few words about the firmware.
Controller - ATMega8515. Such a choice is made only because they have me. In principle, the code is easily ported to ATMega16 (only need to remove the definition of port E, and a couple of nuances).
The controller reads data from the chip through the RTC bus I2C, engaged in loading data into registers, monitors the status of the buttons and listen to UART - as a whole, all as always.
Clock can display the actual time (in HH: MM: SS or HH: MM), the date in the format DD: MM: YY, start counting seconds: SS, have an alarm clock, and can also be used to display numerical information flowing through a COM or USB.
Control is the buttons, as already mentioned, the rear of the enclosure. For each button you can "hang" the implementation of four functions called short or long pressing on the pressing 1, 2 or 3 seconds. Long pressing the supported one, two or three short beeps, respectively.
The functions assigned to the buttons as follows:
A. Pressing 1 on 1s - to set an alarm clock. The screen displays the current alarm set time, the discharge hour is flashing. Buttons 3 and 4 are used to decrease / increase the reading, the new value is confirmed by pressing a buzzer and then starts flashing digit minutes, setting the value of which is similar. If you do not perform any action after the entrance to the installation procedure, after a while the clock returns to native mode.
Two. Pressing 1 for 2c - Set time and date in the following order: hour, minute, year, month, day. Setup is similar.
Three. Clicking on a 3s - Service settings: Mode display the time (1 or 2 - HH: MM: SS or HH: MM), the show dates, in seconds, time display of data from your PC in seconds (unless within that time the PC is not new data arrive, the clock will return to the main mode)
4. Short press button 2 - showing the date for the time configured in the service menu, and then clock back to normal
Five. Short press the 3 button - on / off mode of the second point: the screen shows only a second.
6. Pressing 3 for 1s - on / off indication.
7. Pressing 4 on 1s - on / off alarm clock (with alarm clock in the senior category displayed decimal point).
All settings are stored either in volatile memory chip clock, or in non-volatile memory IC, so that when power is saved.
When the alarm buzzer will sound for as long as you press any button.
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