Schematic diagram of a homemade watch using K176IE18, K176IE13 microcircuits and IV-11 luminescent indicators. A simple and beautiful homemade product for the home. A diagram of the clock, drawings of printed circuit boards, as well as a photo of the finished device in assembled and disassembled form are provided.

I offer for review and possible repetition this watch design on Soviet IV-11 luminescent indicators. The circuit (shown in Figure 1) is quite simple and, if assembled correctly, starts working immediately after switching on.

Schematic diagram

The electronic clock is based on the K176IE18 chip, which is a specialized binary counter with a generator and a multiplexer. Also, the K176IE18 microcircuit includes a generator (pins 12 and 13), which is designed to work with an external quartz resonator with a frequency of 32,768 Hz; the microcircuit also contains two frequency dividers with division factors 215 = 32768 and 60.

The K176IE18 microcircuit contains a special audio signal generator. When a pulse of positive polarity is applied to the input pin 9 from the output of the K176IE13 microcircuit, packs of negative pulses with a filling frequency of 2048 Hz and a duty cycle of 2 appear at pin 7 of the K176IE18.

Rice. 1. Schematic diagram of a homemade watch with IV-11 luminescent indicators.

The duration of the packs is 0.5 seconds, the filling period is 1 second. The audio signal output (pin 7) is made with an “open” drain and allows you to connect emitters with a resistance of more than 50 Ohms without emitter followers.

I took as a basis the schematic diagram of an electronic clock from the site "radio-hobby.org/modules/news/article.php?storyid=1480". During assembly, significant errors were discovered by the author of this article in the printed circuit board and the numbering of some pins.

When drawing a pattern of conductors, it is necessary to flip the signet horizontally in a mirror version - another disadvantage. Based on all this, I corrected all the errors in the signet layout and translated it immediately in mirror image. Figure 2 shows the author's printed circuit board with incorrect wiring.

Rice. 2. Original printed circuit board containing errors.

Figures 3 and 4 show my version of the printed circuit board, it is corrected and mirrored, viewed from the side of the tracks.

Rice. 3. Printed circuit board for the clock circuit on IV-11, part 1.

Rice. 4. Printed circuit board for the clock circuit on IV-11, part 2.

Changes in the scheme

Now I’ll say a few words about the circuit; when assembling and experimenting with the circuit, I encountered the same problems as the people who left comments on the article on the author’s website. Namely:

• Heating of zener diodes;
• Strong heating of transistors in the converter;
• Heating of quenching capacitors;
• Heat problem.

Ultimately, the quenching capacitors were composed of a total capacitance of 0.95 μF - two capacitors 0.47x400V and one 0.01x400V. Resistor R18 has been replaced from the indicated value in the diagram to 470k.

Rice. 5. Appearance of the main board assembly.

Zener diodes used - D814V. Resistor R21 in the converter bases was replaced with 56 kOhm. The transformer was wound on a ferrite ring, which was removed from the old connecting cable between the monitor and the computer system unit.

Rice. 6. Appearance of the main board and the board with indicators assembled.

The secondary winding is wound with 21x21 turns of wire with a diameter of 0.4 mm, and the primary winding contains 120 turns of wire with a diameter of 0.2 mm. These are, however, all the changes in the scheme that made it possible to eliminate the above-mentioned difficulties in its operation.

The transistors of the converter get quite hot, about 60-65 degrees Celsius, but they work without problems. Initially, instead of transistors KT3102 and KT3107, I tried to install a pair of KT817 and KT814 - they also work, a little warm, but somehow not stable.

Rice. 7. Appearance of the finished watch on luminescent indicators IV-11 and IV-6.

When turned on, the converter started up every other time. Therefore, I did not redo anything and left everything as is. As an emitter, I used a speaker from some cell phone that caught my eye, and installed it in the watch. The sound from it is not too loud, but enough to wake you up in the morning.

And the last thing that can be considered a disadvantage or an advantage is the option of transformerless power supply. Undoubtedly, when setting up or any other manipulations with the circuit, there is a risk of getting a serious electric shock, not to mention more dire consequences.

During experiments and adjustments, I used a step-down transformer with 24 volts of alternation on the secondary. I connected it directly to the diode bridge.

I didn’t find any buttons like the author’s, so I took the ones I had on hand, stuck them into the machined holes in the case, and that’s it. The body is made of pressed plywood, glued with PVA glue and covered with decorative film. It turned out quite well.

The result of the work done: another clock at home and a corrected working version for those who want to repeat it. Instead of IV-11 indicators, you can use IV-3, IV-6, IV-22 and other similar ones. Everything will work without problems (taking into account the pinout, of course).

Quite a long time ago, the idea of ​​​​replacing my old watch was long overdue - it was not distinguished either by its accuracy or its special appearance. The idea is there, but with the incentive - either there is no time, or there is no desire to make the Chinese out of a standard remake... in general, a complete mess. And then, one day, on the way home, going into a store selling illiquid goods, a display case with radio tubes from the times of the USSR caught my eye. Among other things, I was interested in the IV-12 light bulb lying forlornly in the corner. Remembering the seller’s remarks in the past: “everything that is there is on display,” I asked even without enthusiasm. … “Miracle, miracle, a miracle has happened!” - it turned out that they had a whole box of these indicators! Damn, I wish I hadn’t sooner.... in general, I bought it;)

In anticipation, when I returned home, the first thing I did was apply voltage to them - they were working! Here, here is a kick in the shaggy tail, here is an incentive to see this miracle in action - the work is in full swing.

Terms of reference:
1. The actual watch;
2. Alarm clock;
3. Built-in calendar (we take into account the number of days in February, including in a leap year) + calculation of the day of the week;
4. Automatic adjustment of indicator brightness.

There is nothing new or supernatural in the circuit: a DS1307 real-time clock, dynamic display, several control buttons, all controlled by ATmega8.
To measure the illumination in the room, a photodiode FD-263-01 was used, as the most sensitive one available. True, it has a small problem with spectral sensitivity - the peak of sensitivity is in the infrared range and, as a result, it senses the light of the sun/incandescent lamps very well, and fluorescent lamps/LED lighting - a C grade.
Anode/grid transistors - BC856, PNP with a maximum operating voltage of 80V.
To indicate the seconds, I installed a smaller IV-6 that was lying around, since it also has a lower filament voltage - a 5.9 Ohm quenching resistor will help it.
For an alarm signal - a piezo emitter with a built-in generator HCM1206X.
The board is wired for: resistors 390K 1206 in size, the rest 0805, transistors in SOT23, stabilizer 78L05 in SOT89, protective diodes in SOD80, three-volt battery 2032, ATmega8 and DS1307 in a DIP package.
From the power supply, the entire circuit consumes +9V up to 50mA along the line, the heat is 1.5V 450mA, the heat relative to the ground is at a potential of -40V, consumption is up to 50mA. Total total maximum 3W.

It was not possible to get a socket for the indicators - the thing was too scarce even to order; instead I used “bushings” from a pair of broken connectors of the RS-232 modem cable. We cut off the “tail” of them - it turns out more compact than the original panels. (note - drill the seat carefully, the spots are small)

First samples:

The accuracy of the DS1307 quartz oscillator leaves much to be desired - after washing the board and selecting quartz piping containers, we managed to achieve something like +/-2 seconds per day. More precisely, the frequency fluctuates depending on temperature, humidity and the position of the planets - not at all what we wanted. After thinking a little about the problem, I decided to order a DS32KHZ microcircuit - a fairly popular temperature-compensated quartz oscillator.
We solder the quartz and this animal is conveniently placed in the free space on a piece of PCB. Connection - now by wiring to the nearby DS1307.

It’s not for nothing that the generator is so expensive - according to the reference book, the manufacturer promises to increase the accuracy of the clock to +/- 0.28 seconds per day. In reality, under acceptable power conditions and temperature ranges, I was not able to see a change in frequency due to external factors. In test mode, in a room, the clock worked for about a week, 2 days of which it was in a lethargic sleep, powered by a standard battery - after that, the error, if you believe the exact time services, did not exceed... +0.043 seconds per day!!! This is happiness! Unfortunately, it was not possible to measure it more precisely in such a short period of time.

Housing assembly:

After assembling the case and “combing” the firmware, the watch has 3 buttons left: let’s call them “A” “B” “C”.
In the normal state, the "C" button is responsible for switching the mode from displaying the time "hours - minutes" to the date "day - month", the second indicator displays the day of the week, then by year, then to the "minutes - seconds" mode, in the fourth pressing - to the original state. Button "A" quickly switches to the time display.
From the “hours - minutes” mode, button “A” switches in a circle to the “alarm clock setting” / “time and date setting” / “indicator brightness setting” mode. In this case, the “B” button switches between digits, and the “C” button actually changes the selected digit.
“Alarm setting” mode, the letter A (Alarm) on the middle indicator means that the alarm is on.
Mode “setting time, date” - when the “seconds” digit is selected, the “C” button rounds them (from 00 to 29 resets them to 00, from 30 to 59 resets them to 00 and adds +1 to the minute).
In the “time and date setting” mode, at the SQW output of m/s DS1307 there is a meander of 32.768 kHz - necessary when selecting quartz/capacitors for the generator; in other modes it is 1Hz.
Mode "adjusting the brightness of the indicator": "AU" - automatic, shows the measured illumination in units. ;) "US" - manual setting in the same units.
Phew, looks like I haven’t forgotten anything.

The schematic diagram of the clock is shown in Fig. The clock is implemented on five microcircuits. The minute pulse sequence generator is made on the K176IE12 microcircuit. The master oscillator uses a RK-72 quartz resonator with a nominal frequency of 32768 Hz. In addition to the minute microcircuit, it is possible to obtain pulse sequences with repetition rates of 1, 2, 1024 and 32768 Hz. This clock uses pulse sequences with repetition frequencies: 1/60 Hz (pin 10) - to ensure the operation of the minute unit counter, 2 Hz (pin 6) - for the initial time setting, 1 Hz (pin 4) - for the “flashing” dot . In the absence of the K176IE12 microcircuit or quartz at a frequency of 32768 Hz, the generator can be made using: other microcircuits and quartz at a different frequency.
Counters and decoders for units of minutes and units of hours are made on K176IE4 microcircuits, which provide counting to ten and conversion of binary code into a seven-element code of a digital indicator. Counters and decoders of tens of minutes and tens of hours are made on K175IEZ microcircuits, which provide counting to six and decoding of the binary code into the code of a digital indicator. For the counters of the K176IEZ, K176IE4 microcircuits to work, it is necessary that a logical 0 (voltage close to 0 V) ​​is applied to pins 5, 6 and 7 or these pins are connected to the common wire of the circuit. The outputs (pin 2) and inputs (pin 4) of the minute and hour counters are connected in series.

Setting 0 dividers of the K176IE12 microcircuit and the K176IE4 microcircuit for the counter of minute units is carried out by applying a positive voltage of 9 V to inputs 5 and 9 (for the K176IE12 microcircuit) and to input 5 (K176IE4 microcircuits) with the S1 button through resistor R3. The initial setting of the time of the remaining counters is carried out by applying tens of minutes to the input 4 of the counter using the S2 button with pulses with a repetition rate of 2 Hz. The maximum time for setting the time does not exceed 72 s.
The circuit for setting 0 counters of units and tens of hours when the value 24 is reached is made using diodes VD1 and VD2 and resistor R4, which implement the logical operation 2I. The counters are set to 0 when a positive voltage appears on the anodes of both diodes, which is possible only when the number 24 appears. To create the “flashing dot” effect, pulses with a repetition frequency of 1 Hz from pin 4 of the K176IE12 microcircuit are applied to the hour unit indicator point or to segment d of an additional indicator.
For watches, it is advisable to use seven-element luminescent digital indicators IV-11, IV-12, IV-22. Such an indicator is an electron tube with a directly heated oxide cathode, a control grid and an anode made in the form of segments forming a number. The glass bottle of indicators IV-11, IV-12 is cylindrical, IV-22 is rectangular. The electrode leads of IV-11 are flexible, while those of IV-12 and IV-22 are in the form of short rigid pins. The numbers are counted clockwise from the shortened flexible lead or from the increased distance between the pins.
A voltage of up to 27 V must be supplied to the grid and the anode. In this clock circuit, a voltage of +9 V is supplied to the anode and grid, since the use of a higher voltage requires an additional 25 transistors to match the outputs of microcircuits designed for a 9 V supply with a voltage of 27 V , supplied to the anode segments of digital indicators. Reducing the voltage supplied to the grid and anode reduces the brightness of the indicators, but it remains at a level sufficient for most applications of the watch.
If the indicated indicators are not available, then you can use indicators such as IV-ZA, IV-6, which have smaller digit sizes. The filament voltage of the cathode filament of the IV-ZA lamp is 0.85 V (current consumption 55 mA) IV-6 and IV-22 - 1.2 V (current 50 and 100 mA, respectively), for IV-11, IV-12 - 1, 5 V (current 80 - 100 mA). It is recommended to connect one of the cathode terminals, connected to the conductive layer (screen), to the common wire of the circuit.
The power supply ensures the clock operates from a 220 V alternating current network. It creates a voltage of +9 V to power microcircuits and lamp grids, as well as an alternating voltage of 0.85 - 1.5 V for heating the cathode and indicator lamps.
The power supply device contains a step-down transformer with two output windings, a rectifier and a filter capacitor. Additionally, capacitor C4 is installed and a winding is wound to power the incandescent circuits of the lamp cathodes. At a cathode filament voltage of 0.85 V, it is necessary to wind 17 turns, at a voltage of 1.2 V - 24 turns, at a voltage of 1.5 V - 30 turns with PEV-0.31 wire. One of the terminals is connected to the common wire (- 9 V), the second - to the cathodes of the lamps. Connecting lamp cathodes in series is not recommended.
Capacitor C4 with a capacity of 500 μF, in addition to reducing supply voltage ripple, allows the operation of hour counters (saving time) for approximately 1 minute when the network is turned off, for example, when moving a clock from one room to another. If a longer shutdown of the mains voltage is possible, then a Krona battery or a 7D-0D type battery with a rated voltage of 7.5 - 9 V should be connected in parallel with the capacitor.
Structurally, the clock is made in the form of two blocks: the main one and the supply one. The main unit has dimensions of 115X65X50 mm, the power supply unit has dimensions of 80X40X50 mm. The main unit is mounted on a stand from a writing instrument.

Indicator, chip	Indicator anode segments								Net	Katsd	General
	A	b b	V	G	d	e	and	Dot
IV-Z, IV-6	2	4	1	3	5	10	6	11	9	7	8
IV-1lH	6	8	5	7	9	3	10	4	2	11	1
IV-12	8	10	7	9	1	6	5	-	4	2	3
IV-22	7	8	4	3	10	2	11	1	6	12	5
K176IEZ, K176IE4	9	8	10	1	13	11	12	-	-	-	7
K176IE12	-	-	-	-	-	-	-	4	-	-	8

Literature

Clock circuit with fluorescent lamps

Many people want and are interested circuit diagram of a clock using vacuum indicators old Soviet times. Well, of course there is a lot of interesting things in this. Watch in retro style, and at night you can see what time it is. You can also insert diodes under the bottom, and it will be like a hint. And so let’s begin to consider this circuit.

The main role is occupied by gas discharge indicators. I used IV-6. This is a luminescent seven-segment indicator with a green glow (In the photographs you will see a bluish tint of the glow, this color is distorted when photographing due to the presence of ultraviolet rays). The IV-6 indicator is made in a glass flask with flexible leads. Indication is carried out through the side surface of the cylinder. The anodes of the device are made in the form of seven segments and a decimal point.

Can be applied indicators IV-3A, IV-6, IV-8, IV-11, IV-12 or even IV-17 with minor changes to the design.

First of all, I would like to note where you can find lamps that were produced in 1983.

Mitinsky market. Many and different. In boxes and on boards. There is room for choice.

It’s more difficult in other cities, maybe you’ll be lucky and you’ll find it in a local radio store. Such indicators are found in many domestic calculators.

You can order from Ebay, Yes Yes, Russian indicators at auction. On average $12 for 6 pieces.

Control

Everything is controlled by the AtTiny2313 microcontroller and the DS1307 real-time clock.

The clock, in the absence of voltage, switches to power mode from a CR2032 battery (as on a PC motherboard).

According to the manufacturer, in this mode they will work and will not fail for 10 years.

The microcontroller operates from an internal 8 MHz oscillator. Don't forget to set the fuse bit.

Setting the time is done with one button. Long hold, incriminating hours, then incriminating minutes. There are no difficulties with this.

Drivers

I used KID65783AP as keys for the segments. These are the 8 “top” keys. I made a choice towards this microcircuit only because I had it. This microcircuit is very often found in display boards for washing machines. Nothing prevents you from replacing it with an analogue one. Or pull up the segments with 47KOhm resistors to +50V, and press the popular ULN2003 to the ground. Just don’t forget to invert the output to the segments in the program.

The display is made dynamic, so a brutal KT315 transistor is added to each digit.

Printed circuit board

The payment was made using the LUT method. The clock is made on two boards. Why is this justified? I don’t even know, I just wanted it that way.

power unit

Initially the transformer was 50Hz. And contained 4 secondary windings.

1 winding - voltage on the grid. After the rectifier and capacitor 50 volts. The larger it is, the brighter the segments will glow. But no more than 70 volts. Current not less than 20mA

Winding 2 - to shift the grid potential. Approximately 10-15 volts. The smaller it is, the brighter the indicators glow, but the “not turned on” segments begin to glow just as brightly. The current is also 20mA.

Winding 3 - for powering the microcontroller. 7-10 volts. I = 50mA

4 winding - Heat. For four IV-6 lamps, you need to set the current to 200mA, which is approximately 1.2 volts. For other lamps, the filament current is different, so take this point into account.