This article will focus on making original and unusual watches. Their uniqueness lies in the fact that the time is indicated using digital indicator lamps. Once upon a time, a huge number of such lamps were produced, both here and abroad. They were used in many devices, from watches to measuring equipment. But after the advent of LED indicators, the lamps gradually fell out of use. And so, thanks to the development of microprocessor technology, it became possible to create watches with a relatively simple circuit using digital indicator lamps.
I think it would not be amiss to say that mainly two types of lamps were used: fluorescent and gas-discharge. The advantages of luminescent indicators include low operating voltage and the presence of several discharges in one lamp (although such examples are also found among gas-discharge indicators, but they are much more difficult to find). But all the advantages of this type of lamp are offset by one huge disadvantage - the presence of a phosphor, which burns out over time, and the glow dims or stops. For this reason, used lamps cannot be used.
Gas discharge indicators are free from this drawback, because a gas discharge glows in them. Essentially, this type of lamp is a neon lamp with multiple cathodes. Thanks to this, the service life of gas-discharge indicators is much longer. In addition, both new and used lamps work equally well (and often used ones work better). However, there are some drawbacks - the operating voltage of gas-discharge indicators is more than 100 V. But solving the problem with voltage is much easier than with a burn-out phosphor. On the Internet, such watches are common under the name NIXIE CLOCK: 
The indicators themselves look like this:
So, everything seems clear about the design features, now let’s start designing the circuit of our watch. Let's start by designing a high-voltage voltage source. There are two ways here. The first is to use a transformer with a secondary winding of 110-120 V. But such a transformer will either be too bulky, or you will have to wind it yourself (the prospect is so-so). Yes, and voltage regulation is problematic. The second way is to assemble a step up converter. Well, there will be more advantages: firstly, it will take up little space, secondly, it has short-circuit protection and, thirdly, you can easily adjust the output voltage. In general, there is everything you need to be happy. I chose the second path, because... I had no desire to look for a transformer and winding wire, and I also wanted something miniature. It was decided to assemble the converter on MC34063, because I had experience working with her. The result is this diagram:
It was first assembled on a breadboard and showed excellent results. Everything started immediately and no configuration was required. When powered by 12V. the output turned out to be 175V. The assembled power supply of the watch looks like this:
A linear stabilizer LM7805 was immediately installed on the board to power the clock electronics and a transformer.
The next stage of development was the design of the lamp switching circuit. In principle, controlling lamps is no different from controlling seven-segment indicators, with the exception of high voltage. Those. It is enough to apply a positive voltage to the anode and connect the corresponding cathode to the negative supply. At this stage, two tasks need to be solved: matching the levels of the MK (5V) and lamps (170V), and switching the cathodes of the lamps (they are the numbers). After some time of thought and experimentation, the following circuit was created to control the anodes of the lamps:
And controlling the cathodes is very easy; for this they came up with a special K155ID1 microcircuit. True, they have long been discontinued, like lamps, but buying them is not a problem. Those. to control the cathodes, you just need to connect them to the corresponding pins of the microcircuit and submit data in binary format to the input. Yes, I almost forgot, it is powered by 5V. (well, a very convenient thing). It was decided to make the display dynamic, because otherwise, you would have to install K155ID1 on each lamp, and there will be 6 of them. The general scheme turned out like this:
Under each lamp I installed a bright red LED (it’s more beautiful this way). When assembled, the board looks like this:
We couldn’t find sockets for the lamps, so we had to improvise. As a result, the old connectors, similar to modern COM, were disassembled, the contacts were removed from them, and after some manipulations with wire cutters and a file, they were soldered into the board. I didn’t make panels for the IN-17, I did them only for the IN-8.
The hardest part is over, all that remains is to develop a circuit for the “brain” of the watch. For this I chose the Mega8 microcontroller. Well, then everything is quite easy, we just take it and connect everything to it in the way that is convenient for us. As a result, the clock circuit included 3 buttons for control, a DS1307 real-time clock chip, a DS18B20 digital thermometer, and a pair of transistors for controlling the backlight. For convenience, we connect the anode keys to one port, in this case it is port C. When assembled, it looks like this:
There is a small error on the board, but it has been corrected in the attached board files. The connector for flashing the MK is soldered with wires; after flashing the device, it should be unsoldered.
Well, now it would be nice to draw a general diagram. No sooner said than done, here it is:
And this is what it all looks like assembled:
Now all that remains is to write the firmware for the microcontroller, which is what was done. The functionality turned out to be as follows:
Display time, date and temperature. When you briefly press the MENU button, the display mode changes.
Mode 1 - time only.
Mode 2 - time 2 min. date 10 sec.
Mode 3 - time 2 min. temperature 10 sec.
Mode 4 - time 2 min. date 10 sec. temperature 10 sec.
When held, the time and date settings are activated, and you can navigate through the settings by pressing the MENU button.
The maximum number of DS18B20 sensors is 2. If the temperature is not needed, you can not install them at all; this will not affect the operation of the watch in any way. There is no provision for hot plugging of sensors.
Briefly pressing the UP button turns on the date for 2 seconds. When held, the backlight turns on/off.
By briefly pressing the DOWN button, the temperature is turned on for 2 seconds.
From 00:00 to 7:00 the brightness is reduced.
The whole thing works like this:
Firmware sources are included with the project. The code contains comments so it will not be difficult to change the functionality. The program is written in Eclipse, but the code compiles without any changes in AVR Studio. The MK operates from an internal oscillator at a frequency of 8 MHz. Fuses are set like this:
And in hexadecimal like this: HIGH: D9, LOW: D4
Also included are boards with bugs corrected:
This clock operates for a month. No problems were identified in the work. The LM7805 regulator and converter transistor are barely warm. The transformer heats up to 40 degrees, so if you plan to install the watch in a case without ventilation holes, you will have to use a higher power transformer. In my watch it provides a current of around 200mA. The accuracy of the movement is highly dependent on the quartz used at 32.768 KHz. It is not advisable to install quartz purchased in a store. The best results were shown by quartz from motherboards and mobile phones.
In addition to the lamps used in my circuit, you can install any other gas-discharge indicators. To do this, you will have to change the board layout, and for some lamps the voltage of the boost converter and the resistors on the anodes.
Attention: the device contains a high voltage source!!! The current is small, but quite noticeable!!! Therefore, you should be careful when working with the device!!!
PS Article one, I might have made a mistake/messed up somewhere - suggestions and suggestions for correction are welcome.
I welcome users again and keep my promise!
Today I’m starting to post a detailed photo report on the manufacture of watches using gas discharge indicators (GDI). The IN-14 is taken as the basis.
All manipulations in this and the following posts are accessible to a person without experience, you just need to have a little skill. I will divide the work into several parts, each of which will be described in detail by me and posted online.
Let's proceed to the first stage - etching the boards. After researching the literature, I found several technologies:
- . To operate, you need three components: a laser printer, ferric chloride and an iron. The method is the simplest and cheapest. It has only one drawback - it is difficult to transfer very thin tracks.
- Photo resist. To work, you need the following materials: photo-resist, printer film, soda ash and a UV lamp. The method allows you to etch boards at home. The downside is that it is not cheap.
- Reactive ion etching (RIE). The work requires chemically active plasma, so it cannot be done at home.
Most often, anodic etching is used. The anodic etching process involves the electrolytic dissolution of the metal and the mechanical removal of oxides by the released oxygen.
It is quite understandable that I chose the LUT method for etching the boards. The list of necessary equipment and materials should look something like this:
- Ferric chloride. It is sold in radio products at a price of 100-150 rubles per jar.
- Foil fiberglass. Can be found in radio stores, radio flea markets or factories.
- Capacity. A regular food container will do.
- Iron.
- Glossy paper. Self-adhesive paper or a plain page from a glossy magazine will do.
- Laser printer.
IMPORTANT! The print version must be a mirror image, since when the image is transferred from paper to copper, it will be reflected back.
You need to mark and cut a piece of PCB for the board. This is done with a hacksaw, a breadboard knife or, as in my case, a drill.
After that, I cut out a sketch of the future board from paper and attached the design to the textolite (on the foil side). The paper is taken with a reserve in order to wrap the PCB. We secure the sheet on the reverse side with tape to secure it.
From the side of the drawing, we draw across the future board with an iron several times through sheet A4. It will take at least 2 minutes of intense ironing to transfer the toner to copper.
We place the workpiece under a stream of cold water and easily remove the paper layer (the wet paper should come off freely on its own). If the surface heating was not sufficient, small pieces of toner may come off. We finish them with cheap nail polish. As a result, the blank for the board should look like this:
In a prepared container, prepare a solution of ferric chloride and water. It is better to use hot water for these purposes, this will increase the reaction rate. It is better to avoid boiling water, as high temperatures will deform the board. The finished liquid should have the color of medium-brewed tea. Place the board in the solution and wait for the excess foil to completely dissolve.
If you occasionally stir the solution in the container, the reaction rate will also increase. Ferric chloride is not dangerous for the skin of your hands, but your fingers may become stained.
To make the process more clear, I partially placed the board in the solution. What changes should happen can be seen in the photo:
Excess copper dissolves in the composition after about 40 minutes. After which the etching process can be considered complete. All that remains is to make a few holes. We mark with an awl and drill small holes with a drill. The tool must operate at high speeds so that the drill does not move out. The result should look something like this:
The second stage of manufacturing watches using GRI is soldering the components. I will talk about this in my next post.
Download:
- Program ).
- Post about soldering components - ;
- Post about microcontroller firmware – ;
- Post about making the case - .
Convenient fringe cutter for transformers. Soldering iron heating regulator with power indicator
In the last century, gas-discharge indicators were used very actively on many devices: in watches, measuring equipment, frequency meters, oscilloscopes, scales and many others. Over time, they were replaced by liquid crystal displays, the manufacturing technology of which is simpler and less expensive, and most importantly, they are more compact and have a larger number of digits. Liquid crystal displays make it possible to display readings with greater accuracy.
Scope of application today
Nowadays the industry no longer makes gas-discharge indicators with numbers, but at one time they were churned out so many that they are still collecting dust in warehouses and private stocks. They can already be called antiques, just like, for example, many homes have vintage candlesticks that are used as a decorative element of the interior. Likewise, clocks with gas-discharge lamps fascinate with their illumination and are an excellent addition to the interior of various rooms, especially those furnished in a retro style.
The thing is beautiful and useful, but, alas, it is no longer produced in factories. You can make them yourself or buy ready-made ones from people who specialize in their production. Many clock circuits have been developed using gas-discharge indicators on old and new microcircuits. Let's consider the simplest options.
Watch assembly steps
First, you need to understand the operating principle of IN-14 indicator elements; practically these are neon light bulbs with a group of cathodes in the form of numbers. Depending on the power supply, one or another cathode glows alternately; the principle of an incandescent lamp with a gas-discharge process is used.
The service life of such indicators is enormous, because there is no long-term and heavy load on one cathode. For full illumination, a voltage of at least 100 V is required, so let’s start the design with a power source.
power unit
The option with a transformer, the secondary winding of which will have 170 or 180 V, is immediately excluded due to its large dimensions and weight. Selecting iron, wires and winding yourself is a thankless and tedious task. It is more practical to use a voltage converter on the MC34063 chip, which has small dimensions, weight and stable parameters.
All elements are mounted on a printed circuit board; after assembly, in most cases, no adjustment is required; with 10–12 V, the converter produces 175–180 V. As you can see, there is a transformer in the circuit, but it is very small and easily accessible for quick self-production; one can be purchased at retail networks. At the output of the secondary winding, 9–12 VAC goes to the diode bridge (rectifier). The linear stabilizer LM7805 is designed to power the electronic elements of watches.
Circuit for turning on lamps
This circuit solves the problem of matching the control voltage on the 5 V microcircuit and the controlled supply voltage of the anodes. A positive potential of 180 V is applied to the anode, and a negative potential is applied to the cathodes of the corresponding numbers.
The cathodes are switched on using a circuit based on the old K155ID1 microcircuit, which is powered by a voltage of 5 V, which in our case is very successful. 155-series microcircuits have been discontinued, but are not in short supply; they can easily be purchased in retail chains and radio markets. In order not to solder a microcircuit to each lamp, the cathode control circuit is made according to a dynamic principle.
Now the power supply, cathode and anode control circuit must be connected to the DS1307 clock processor; the Mega8 microcontroller is ideal for coordination.
Watch with controller and control buttons
This scheme includes:
- watch DS1307;
- Mega8 controller;
- DS18B20 digital thermometer;
- transistors for LED backlighting;
- buttons to control time settings.
If necessary, this circuit can be significantly simplified by removing the LED backlight, digital thermometer and lamps for discharging seconds with cathode and anode control elements.
Microcontroller firmware
The software for the clock from gas-discharge indicator lamps is written in Eclipse, transmitted without distortion to AVR Studio, codes with comments, which greatly simplifies the process.
As a result of the firmware, certain modes and the process of managing them are installed. When you briefly press the “MENU” button, the following modes are displayed in a circle:
- mode No. 1 – time (displayed constantly);
- mode No. 2 – 2 min. time, 10 sec. date of;
- mode No. 3 – 2 min. time, 10 sec. temperature;
- mode No. 4 – 2 min. time, 10 sec. date and 10 sec. temperature;
- The time and date setting mode is set by holding the “MENU” button;
- a short press on the “UP” button (2 seconds) displays the date, holding this button turns the backlight off or on;
- short press “DOWN” (2 sec.) displays the temperature;
- brightness reduction by hourly program from 00.00 to 7 am.
Connection of main elements and operating features
Ultimately, the entire system consists of three printed circuit boards:
- Power supply, voltage converter on base MC34063
- Board with controller Mega8 and DS1307 watch
For compactness, the board is made with a double-sided arrangement of elements; this version of printed circuit boards is not a dogma; there are others. When the clock, control of the cathodes and anodes are mounted on one board, and the power supply on another, smaller lamps - IN-8 - are used to discharge seconds. Sometimes the lamps are placed on a separate panel and a two-level design is made; on the first level there is a board with a clock microcircuit and elements for controlling the cathodes and anodes. At the second level there is a board with panels for lamps; everything depends on the developer’s imagination.
IN-14 lamps are no longer in production; there may be a problem with purchasing panels for them. In this case, you can use the contacts of D-SUB connectors of the “female” format or collet rulers that match the diameter.
The plastic of the ruler can be carefully crushed with pliers and the contacts can be removed, which are soldered into the drilled holes on the printed circuit board.
Now all that remains is to pack this structure into a case (the simplest option is a rectangular box). The material can be very varied: plastic, plywood, covered with leather or other decorative material.
The power supply transformer heats up by no more than 40 °C, so it is recommended to make ventilation holes in the case to ensure a stable current of 200 mA. The accuracy of the clock depends on the stable operation of 32.768 KHz quartz, which is recommended to be taken from PC motherboards or cell phones, since low-quality products are often found in retail chains.
This method of making watches using gas-discharge lamps can be carried out by a person who has certain knowledge in electronics and practical skills. Beginners can use the services of the site http://vrtp.ru/index.php?showtopic=25695. You can order ready-made printed circuit boards for 800 rubles with detailed instructions that specify what to solder and where. For 2,500, a complete “Do it yourself” kit is sold, on lamps with a stitched microcircuit and other parts. You can buy a ready-made watch for 3,500 rubles, but this is not interesting if you want to assemble something with your own hands.
Answer
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A simple clock - a thermometer with gas-discharge indicators.
Watch features
Time:
Date of:(Date - Month - Day of the week)
Temperature:
6 display modes and auto-display of date and temperature every 35 seconds.
Press the "-" button to select display modes.
http://www.youtube.com/watch?v=QReDKfZJKd0
The watch is assembled using a minimum of microcircuits:
PIC16F628A- clock controller.
DS1307- the watch itself.
BU2090- cathode decoder.
MAX1771- voltage transformer.
DS18B20- temperature sensor - If you don't need a thermometer, you don't need to install it.
DS32KHz- generator microcircuit for precision.
If accuracy is not needed and you just select the exact quartz at 32.768
then DS32KHz can not be installed.
Description of buttons:
The "-" button is in the clock setting mode and the button is used to cycle through display modes in the clock operating mode.
Button "OK" - to enter the clock setting mode.
The "+" button in the clock setting mode and the date and temperature display button in the clock operating mode.
Display modes:
1 - the numbers fade out smoothly and new ones appear smoothly.
2 - the clock works as usual; in this mode the “pendulum” works.
3 - the numbers change when changing by brute force; in this mode the “pendulum” works.
4 - the numbers overlap each other when changing.
5 - display mode changes every day at 00:00.
6 - indication mode changes every hour.
Enable/disable automatic display of date and temperature every 35 seconds.
Press and hold the “+” button for 3 seconds to display the date/temperature.
Time setting:
To set the time, press and hold the “OK” button for 3 seconds while the time is displayed.
The watch enters time setting mode and the hours begin to flash.
Use the “-” and “+” buttons to set the hour and press the “OK” button and proceed to setting the minutes.
And so on in the sequence hour > minutes > date > month > day of the week.
When you hold the "-" or "+" buttons for a long time, the numbers automatically decrease or increase on their own.
Setting the cathodes, that is, the order of numbers.
Any lamp can be used in the clock.
For the board included in the project, you can use any lamps with flexible leads
Type IN-8-2 or IN-14 or IN-16 or IN-17.
The project also contains a board and firmware for IN-12 - The firmware is different because the lamps are not in place, and a board for IN-18.
The controller firmware is designed to use IN-14 in the native board,
if you use other lamps or draw your own board
After assembling the board and starting the clock, you need to reassign the numbers.
Because their order is violated - for example, instead of 0 there will be 7 or instead of 5 - 3.
Purpose of numbers:
Necessary if you will use your board with other lamps.
Or other lamps for this board - for example IN-8-2 or IN-16.
Cathodes can be connected to the BU2090 as convenient.
The only exception is for points if they are in the lamps (14 - right, 15 - left points, BU2090 pins).
If there are no points, then you don’t have to connect them.
Press and hold the OK button and turn on the clock.
A number in the 1st or 3rd digit lights up.
We release the button and the numbers begin to be sorted.
We need to assign numbers from 0 to 9.
When they appear, press the “+” button and so on sequentially from 0 to 9.
After which the 4th digit lights up and 0 and 1 begin to blink.
This is to enable/disable the running dot.
If you press the "+" button to 0, the function is disabled.
Then the 5th digit lights up - this is the permission for the blinking of the second lamps.
In case you place the second lamps in the center instead of the second dots.
After which the clock goes into operating mode.
The boards were drawn using Sprint Layout 3.0.
Photo of the top part of the board with labeled elements for greater clarity.
Are available
Buy in bulkThe kit for assembling clocks with lamps IN-14 is a construction kit for assembling a tube clock with gas-discharge indicators in a retro style. The watch is equipped with an alarm clock and has non-volatile memory. The kit includes boards and a complete set of components for assembly (supplied with radio tubes). At the end of the exciting assembly, you receive a finished product that will delight you with warm lamp light.
The kit is designed to teach soldering skills, read circuit diagrams and practical setup of assembled devices; it allows the radio amateur to understand how a microcontroller works. It will be interesting and useful in learning the basics of electronics and gaining experience in assembling and configuring electronic devices.
Specifications
Peculiarities
- Cathode anti-poisoning mode (before changing minutes, all numbers in all lamps are quickly searched)
- Alarm
Additional Information
IN-14 gas-discharge indicators were produced in the last century and were used to display information (digital, symbolic) based on a glow discharge. Currently, these lamps are used to create watches.
The watch is equipped with an alarm clock.
The watch has a non-volatile memory - a CR 2032 battery is included.
The watch is controlled by three buttons. Using the "function" button, you can cycle through modes. Using the “value setting” buttons, the value is changed in one mode or another.
Power cable not included.
Structurally, the device is made on two printed circuit boards made of foil fiberglass with dimensions of 116x38 mm. The distance between the connected boards is 11 mm. Mount components to a height of up to 10 mm. Pay special attention to the sizes of polar capacitors. For a “harmonious” installation of indicator lamps, insert two matches between the terminals of IN-14. The comb of pins on the indicator board is mounted on the side of the tracks (we solder the pins, then move the plastic “clip” towards the board).
Once a minute, when the sign changes, the lamp cathode anti-poisoning mode is switched on. At this moment, all the characters in each indicator are enumerated, which makes the clock work even more effective.
ATTENTION! After switching on, do not touch the components and current-carrying paths of the board; the circuit is under high voltage of about 180V. This voltage is required to power the paw indicators. Be careful to follow the rules for working with high voltage.
Articles
Scheme
Electrical diagram
Contents of delivery
- Indicators IN-14 - 4 pcs.
- Set of electronic components - 1 pc.
- Printed circuit board - 2 pcs.
- Instructions - 1 pc.
What is required for assembly
- Soldering iron
- Solder
- Side cutters
Settings
- A correctly assembled device does not require configuration and starts working immediately.
Precautionary measures
- ATTENTION! After switching on, do not touch the components and current-carrying paths of the board; the circuit is under high voltage of about 180V. This voltage is required to power the paw indicators. Be careful to follow the rules for working with high voltage.
Maintenance
- If after turning on the indicator shows double values, you need to thoroughly rinse the board again to remove flux residues.
Attention!
- In order to prevent peeling of printed conductors and overheating of elements, the soldering time of each contact should not exceed 2-3 s
- For work, use a soldering iron with a power of no more than 25 W with a well-sharpened tip.
- It is recommended to use solder brand POS61M or similar, as well as liquid inactive flux for radio installation work (for example, a 30% solution of rosin in ethyl alcohol or LTI-120).
Questions and answers
- Good afternoon. 1) Are there any cases for sale for this watch (blanks) 2) Do these watches have LED backlighting for IN-14 bases?
- Good afternoon. 1. There are no cases, you need to make them yourself. 2. No, there is no backlight.
