Do-it-yourself clock on gas-discharge lamps. Clock on gas-discharge indicators - etching of circuit boards

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:

1. . 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.
2. 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.
3. 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:

1. Ferric chloride. It is sold in radio products at a price of 100-150 rubles per jar.
2. Foil fiberglass. Can be found in radio stores, radio flea markets or factories.
3. Capacity. A regular food container will do.
4. Iron.
5. Glossy paper. Self-adhesive paper or a plain page from a glossy magazine will do.
6. 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 PCB (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 is 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 making watches using GRI is soldering the components. I will talk about this in my next post.

Download:

1. 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

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, ranging 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.

Recently, watches with gas-discharge indicators have become very popular. These clocks give many people the warm light of their lamps, create comfort in the home and an indescribable feeling of breathing the past. Let's figure out in this article what these watches are made of and how they work. I’ll say right away that this is a review article, so many unclear places will be discussed in more detail in the following articles.

The clock can be divided into the following functional blocks:

1)High voltage block

2)Display block

3)Time counter

4)Backlight unit

Let's look at each of them in more detail.

High voltage block

In order for the number inside the lamp to light up, we need to apply voltage to it. The peculiarity of gas-discharge lamps is that the voltage required is quite high, about 200 Volts DC voltage. The current for the lamp, on the contrary, should be very small.

Where can you get this kind of tension? The first thing that comes to mind is a power outlet. Yes, you can use rectified mains voltage. The diagram will look like this:

The disadvantages of this scheme are obvious. This is the absence of galvanic isolation; there is no safety or protection of the circuit at all. Thus, it is better to check the lamps for functionality, while being extremely careful.

In watches, the designers took a different route, increasing the safe voltage to the required level using a DC-DC converter. To put it very briefly, such a converter works on the principle of a swing. We can, by applying a slight hand force to the swing, give it a fairly large acceleration, right? The DC-DC converter is the same: we pump low voltage to high voltage.

I will give one of the most common converter circuits (click to enlarge, the circuit will open in a new window)

A circuit with a so-called semi-driver field-effect transistor. Provides enough power to power six lamps without getting as hot as an iron.

Display block

The next functional block is indication. It consists of lamps in which the cathodes are connected in pairs, and the anodes are connected to optocouplers or transistor switches. Typically, watches use dynamic display in order to save space on the printed circuit board, miniaturize the circuit, and simplify board layout.

Time counter

The next block is a time counter. The easiest way to do this is on a specialized DS1307 chip

It provides excellent time accuracy. Thanks to this chip, the watch maintains the correct time and date, despite a long power outage. The manufacturer promises up to 10 years (!) of battery life from a CR2032 round battery.

Here is a typical connection diagram for the DS1307 chip:

There are also similar microcircuits that are produced by many companies producing radio components. These chips can provide particularly accurate timekeeping, but they will be more expensive. It seems to me that their use in household watches is not advisable.

Backlight block

The backlight unit is the simplest part of the watch. It is installed at will. These are just LEDs under each lamp that provide background lighting. These can be single-color LEDs or RGB LEDs. In the latter case, you can choose any color of the backlight or even make it change smoothly. In the case of RGB, an appropriate controller is required. Most often, this is done by the same microcontroller that counts time, but to simplify programming, you can install an additional one.

Well, now a few photos of a rather complex clock project. It uses two PIC16F628 microcontrollers to control the time and lamps and one PIC12F692 controller to control the RGB backlight.

Turquoise backlight color:

And now green:

Pink:

All these colors can be adjusted with one button. You can choose any one. RGB diodes are capable of producing any color.

And this is a piece of a high-voltage converter. Below in the photo is a field-effect transistor, an ultra-fast diode and a storage capacitor of a DC-DC converter

The same converter, bottom view. An SMD choke and an SMD version of the MC34063 chip are used. In the photo, the remaining flux has not yet been washed off.

And this is a simplified four-lamp version of the watch. Also with RGB backlighting

Well, this is a classic clock structure based on Sunny Clock gas-discharge lamps, static backlighting and a slightly unusual way of controlling lamps using a pair of K155ID1 decoders

In the next article we will talk in more detail about DC-DC converters and high voltage production. We will also analyze in detail the process of assembling such a converter and run a lamp from it.

Thank you everyone, El Kotto was with you. Join the group in contact

DIY clock with IN-14 lamps

I have long wanted to post an article on making DIY watches with IN-14 lamps, or as they say, a watch in the steam punk style.

I will try to present only the most important things step by step and focusing on key points. The clock indication is clearly visible both day and night, and they themselves look very nice, especially in a good wooden case. Anyway, let's get started.

Device diagram (to enlarge - like everywhere else - click):

This watch has IN-14 gas-discharge indicators. They can also be replaced with IN-8, naturally taking into account the differences in pinout. The indicator pins are numbered clockwise from the pin side. For IN-14, pin 1 is indicated by an arrow.

Watch characteristics:

Supply voltage, V	12
Current consumption, no more, mA	200
Typical current consumption, mA	150
Type indicators	IN-14
Time display format	Hours\Minutes\Seconds
Date display format	Day\Month\Year
Number of control buttons	2
Alarm clocks	2
Discreteness of setting the alarm time, min	5
Software gradations for adjusting the brightness of indicators	5

Atmega8 microcontroller in TQFP package. The clock does not work with a controller in a DIP package. Real time clock DS1307. The sound emitter has a built-in generator and a supply voltage of 5V. All necessary project files - board, controller firmware - download

Fuses:

More photos:

The boost voltage converter is based on the MC34063A chip. (MC33063A). In terms of prevalence and cost, it is somewhat inferior to the 555 timer, on which such a converter can be built, but it is cheaper and more accessible than the MAX1771.

Non-polar capacitors are ceramics, polar capacitors are Low ESR electrolytes. If Low ESR is not available, place ceramics or film parallel to the electrolyte. The choke in the boost converter is 220 µH for a current of 1.2A. The minimum rated inductor value is 180 µH, the minimum rated inductor current is 800 mA.

Two K155ID1 housings operate as decoders. The anode voltage switch uses a TLP627 optocoupler. The values ​​of R23 and R24 must be selected independently, depending on the degree of luminescence. Without them, the currents through the points exceed the permissible level. When installing, we do not push the indicators all the way in. Since the housings of all indicators are individual, they will need to be aligned with respect to the printed circuit board and with each other.

Clock control on IN-14:

The transition from mode to mode occurs along the ring with the button "MODE".

The value is set using the button "SET".

The adjusted value either blinks or is brighter.

Setting the seconds value involves resetting them to zero.

Setting the value of minutes, hours, day, month, year consists of adding 1 to the current value along the ring to the maximum value, after which the value is reset.

The alarm clock minutes are set from zero in increments of 5 minutes (00-05-10-15:55).

If the watch is not in the main mode and you stop pressing the buttons, then after a few minutes the watch returns to the main mode.

Cancel the alarm sound using the button "SET".

In this case, the next time the alarm time is reached, the alarm will be activated. Commas in tens and units of seconds indicate the activity of alarms 1 and 2, respectively. The operating modes of the clock are shown in the table. Red symbolizes brightly lit discharges, orange indicates dimly illuminated discharges, and black indicates extinguished discharges. For time: H - hours, M - minutes, S - seconds. For the date: D - day of the month (day), M - month, G - year. To set an alarm: 1 - alarm 1, 2 - alarm 2, X - no value (switched off).

First switching on, controller programming and setup. First check that the clock circuit is installed correctly. Then check the power circuits for short circuits. If not found, try applying power to the input from a 12V source. If smoke does not come out, check the voltage of the power supply circuit D5V0. Using trimmer resistor RP1, set the output of the boost converter to a voltage of 200V (for the indicated ratings). Wait a few minutes. The circuit elements should not heat up noticeably. This is especially true for the inductor of a high-voltage converter. Its overheating indicates an incorrectly selected rating or a design with too low operating current. This throttle must be replaced with a more suitable one.

From now on, you will need a VT1 battery type CR2032. As a last resort, short-circuit the contacts of the battery socket, but then you will set the time and date every time the power supply is cut off.

Program sequentially Flash And EEPROM microcontroller using the supplied firmware. This operation must be done in the specified sequence. The indicators will show " 21-15-00 ". The seconds will tick by. If you still haven't connected BT1, then instead of the time and date you will see something like " 05-05-05 ".

Set the time, date, and alarms in accordance with the table describing operating modes. When you get to the brightness setting, programmatically turn on the minimum brightness of the indicators. Adjust the boost converter so that each of the indicators glows at minimum brightness, but fully. That is, it should not be the case that part of the indicator number is lit and part is not. Then programmatically set the maximum brightness and check the glow of the indicator numbers.

The indicators should not glow too brightly, and there should be no “volumetric” glow. Brightness correction is again done using RP1. After this, check the glow again at minimum brightness and so on until acceptable results are obtained. If acceptable results are not obtained, try to select the values ​​of the anode resistors and repeat the above steps.

Such watches will compare favorably with ordinary Chinese ones, based on LEDs, which, by the way, cost a lot of money.

Video of work in our VK group