Make a clock using fluorescent lamps with your own hands. Scheme of the simplest electronic clock Clock circuits on indicators 11

A. Anufriev, I. Vorobey

WITH INDICATION ON IV-22

Electronic clocks with time indication by gas-discharge indicators of the IN type require the use of a large number of high-voltage transistors P307...P309, KT605 or special microcircuits with a high degree of integration that decipher the code of binary counters into decimal ones, simultaneously switching the cathodes of indicator lamps. All these elements are not always available to radio amateurs. In addition, IN type indicators have a number of disadvantages. To power them, a high voltage source of 180...200 V is required, which increases the labor intensity of manufacturing the power supply network transformer; they also have poor visibility and difficulty distinguishing numbers in bright external lighting.

Electronic watches with time indication on IV type vacuum luminescent indicators are free from all these shortcomings. The numbers in indicators of this type are formed from seven segments, displayed in certain combinations. All anode segments are located in the cylinder in the same plane, which increases the viewing angle of the displayed numbers 120...140°, clearly visible even in bright light. The pleasant green glow of the segments allows you to use an electronic watch at home instead of a night light.

The clocks are made on microcircuits of the 217 and 155 series. Their operation is determined by the instability of the quartz resonator and in this case is about 10 s. Time counting is ensured with an accuracy of 1 s using six IV-22 indicator lamps. The clock is powered from an AC mains voltage of 220 V. The consumption does not exceed 7 W (with the indication turned off 5 W). Electronic watches allow you to manually correct their course using precise time signals, preliminary update the minute and hour counters without disrupting the connection between the input of the installed counter and the output of the previous one, and turn off the time indication without disturbing the count. There is an automatic reduction in the brightness of the indicators at night and an alarm sound at a preset time.

A schematic diagram of an electronic clock is shown in Fig. 1. They include an on-chip crystal oscillator D1 and resonator Z1, frequency divider with division ratio 105 (D4…D8), seconds counters (U 1.1), minutes (U1.2) and hours (U2), sound alarm unit (S7…S10,D11…D15,V21…V26, B1), single pulse generators (D2,D3 andD9,D10) and -taniya (77, V1…V16, A1).

Produces rectangular pulses with a repetition rate of 100 kHz. From pin 11 of the microcircuit D1 The generator pulses arrive at a frequency converter, which converts them into second pulses. The frequency divider is made on five 155IE1 microcircuits (D4…D8), which are decimal counters with a conversion factor of 10. From the output of the frequency divider (output 5 microcircuits D8) pulses with a repetition rate of 1 Hz are sent to the second pulse counter U 1.1 and into the sound alarm unit to modulate the alarm tone. The counter of second pulses (Fig. 2) consists of a counter of units of seconds (microcircuit D5…D10) with a conversion factor of 10 and a counter of tens of seconds (microcircuits D11…D14) with a conversion factor of 6. At the output of the second counter, pulses are generated with a repetition period of 1 minute. These impulses, twice inverted by the elements D3.1 And D3.2(see Fig. 1) are sent to the input of the minute pulse counter. To preset the minute counter on the chips D2,D3 a single-pulse generator has been assembled, allowing you to get rid of the influence of “bounce”. Mechanical contact is usually accompanied by a number of short-term transitions from a closed state to an open state. Bouncing can lead to a burst of pulses instead of the desired single pulse or voltage drop.

Inverter chips D2 educated R.S. trigger. Zero applied when pressing the button S2 to one of the trigger inputs, sets it to one stable state, and when released, to another. When the button is released S2 A negative voltage drop appears at the minute counter input, changing its state by one. However, this will only happen when at the entrance 8 element D3.2 there is a logical one level, and at the output of the second counter there is a corresponding zero level.

In order to be able to install the mi-counter at any output voltage of the second counter, without introducing additional switching, the input 4 element D3.1 and integrating chain R6C8. When there is a high logic level at the output of the second counter, the introduction of the chain R6C8 allows at the moment the button is released S2 delay the logic zero level at the input 4 element D3.1 and receive simultaneously at both inputs of the element D3.2 logical unit level. In this case, at the output of the element D3.2 a negative pulse is generated, changing the state of the minute counter.

Rice. 1. Schematic diagram of an electronic clock

Rice. 1. Schematic diagram of an electronic clock (ending)

Rice. 2. Schematic diagram of a seconds or minute counter

Rice. 3. Schematic diagram of a units and tens hours counter

Schematic diagram of a minute counter U1.2 similar to the seconds counter circuit U 1.1(see Fig. 2). The only difference is that in the minute counter the outputs of the microcircuits D1…D4 connected to switches S7…S8 preset alarm time. The seconds counter does not use these connections.

At the output of the minute counter, pulses are generated with a repetition period of 1 hour, which, through a single pulse generator similar to that discussed above (see Fig. 1) (D9,D10) arrive at the input of the hour counter U2, also consisting of unit counters (microcircuits D5…D10) and tens of hours (microcircuits D11…D12)(Fig. 3).

Counters, the states of which are indicated on seven-segment indicators, can be assembled according to any scheme, but the most convenient are those that require logical elements with the smallest number of inputs for decoding and allow you to do without key transistors, as well as IE microcircuits that are still in short supply , ID. Currently, microcircuits of the 155 and 217 series are common among radio amateurs. They contain many designs and individual components, described in the magazines “Radio”, in the collections “To Help the Radio Amateur”, etc. Many radio amateurs are trying to solve the issue of implementing various digital devices on R.S. triggers that do not have a counting input, since often, due to their limited use, they are most accessible in amateur radio practice.

The counters of the proposed electronic clocks were developed taking into account all these considerations. All of them differ only in the capacity and number of logical elements in the decoders, so it is enough to consider the operation of one of them - a counter of units of seconds or units of minutes (see Fig. 2). A special feature of the counter is that it is built on triggers with separate settings of the “O” and “1” states (microcircuits D6…D10) using only one trigger with a counting input (D5). A trigger with a counting input is not involved in dividing the frequency of input pulses and is needed only as an auxiliary one to control the installation of a different stable state R.S. triggers (microcircuits D6…D10), combined into a ring shift register. R.S. flip-flops switch to state only when a logical one arrives at all inputs of level 5 and is present on at least one input R logical zero (except for special input R, used to reset the trigger to zero). And vice versa, when a single level arrives at all inputs R and the presence of a logical zero on at least one input 5, the trigger is set to the zero state. If at one of the inputs S and at one of the inputs R The logical zero level is maintained when the potentials at other inputs connected to the first ones are changed by AND, the state of the trigger does not change.

Rice. 4. Timing diagrams illustrating the operation of a five-bit register

When building connections between the inputs and outputs of flip-flops, as shown in Fig. 2, conditions for installing each R.S. triggers to the desired state are created according to the previous and input (D5) triggers, and to set the first R.S. trigger { D6)- triggers D5 And D10.

As can be seen from Fig. 4, which shows timing diagrams illustrating the operation of a five-bit register, trigger D5 switches by the fall of each positive pulse arriving at its counting input, and controls the setting of all R.S. triggers first to the one state and then to the zero state. The first five input pulses trigger D6…D10 are alternately set to one, and five subsequent pulses return them to the zero state again. At the moment the last trigger of the register switches to the zero state, a pulse is generated at its output to transfer one to the most significant digit.

Signals from the register outputs are converted by a decoder based on logic elements with an open collector output (Dl,D2,D3.1,D3.2). Signals for alarm clock control and a segment digital indicator are removed from the decoder outputs. The formation of numbers is carried out by blanking out unused segments. The number at each output of the decoder corresponds to the register state at which a logical zero level is formed at this output. The diodes of the decimal code converter into seven-segment indicators (diodes) connected to this output VI..,V14,V23…V26, resistors R1…R7) Through the open output transistor of the inverter, the unused anode segments of the indicator are bypassed, reducing the anode voltage on these segments to approximately 1 V. As a result, they go out and a figure corresponding to this state of the register is formed. Diodes V23…V28 can be excluded from the seconds counter circuit. They are necessary only in the minute counter to prevent mutual influence of the decoder outputs on the time the alarm clock sounds.

The tens of hours counter (see Fig. 3) is built on two triggers (microcircuits D11,D12). The first one is universal JK trigger, the second is a trigger with separate setting of states 0 and 1. When both triggers are in the zero state, a high level from the inverse output R.S. trigger (D12) goes to the base of the key transistor V28 and unlocks it. On the collector of the transistor V28 decreases to the level of logical zero, and on the indicator H2 the number 0 is displayed. Transistor V28 used in order not to install an additional microcircuit in which only the inverter will be used. When a trigger arrives at the input D11 of the first pulse from the hour unit counter, both triggers are set to one. A low level appears at the output of the element D3.3, and the number 1 is formed. With the arrival of the second input pulse, the trigger D11 returns to the zero state, and the trigger D12 remains in unit, since its inputs 3 and 7 from the inverse output the potential of -gical zero is applied. In this state, the counter from the inverse output of the trigger D11 and direct trigger output D12 to the inverter inputs D3.4 single voltage levels are received. At the inverter output D3.4 a logical zero potential appears, and on the indicator H2 the number 2 is formed.

On the chip D14 and transistor V29 The pulse generator for resetting the hour counter at midnight has been completed. After twenty or twenty pulses arrive at the inputs of the hour counter Chilly element D14.1 Logical one levels arrive and the reset device is prepared for operation. When, after the twenty-fourth pulse, the level of one appears at the direct output of the trigger D9 hour unit counter, at the output of the element D14.1 zero level appears. As a result, the standby multivibrator on the element is turned on D14.2 and transistor V29. On the transistor collector V29 a negative pulse is generated, which sets the hour counter to zero.

On microcircuits D4,D13,D15(see Fig. 3) a device has been installed to automatically reduce the brightness of digital indicators at night. At 22 o'clock from the exits of the elements D1.3 And D3.4 to inverter outputs D13.1,D13.2 logic zero signals will be sent. At the element output D13.3 a negative voltage drop will appear, which will establish D15 per unit. From the output 9 trigger D15 the level will go to the base of the transistor V13 power supply (see Fig. 1). Transistor V13 will open and shunt the zener diodes Vll,V12. As a result, the output voltage of the “+ 27 V” stabilizer will drop to 9 V, and the brightness of the indicators will decrease. At 05 o'clock in the same way at the output of the element D4.3(see Fig. 3) a negative voltage drop will appear, which will set the trigger DJ5 to its original state, and the glow of the numbers will increase. The introduction of a brightness control device was required due to the very bright glow of the indicators at night. The time during which the indicators glow with less brightness is chosen arbitrarily. It can be changed by connecting the inverter inputs D4.1,D4.2,D13.1,D13.2 to the corresponding outputs of the decoders.

To increase the digital display, you can turn off the time display. The button is used for this purpose S11(see Fig. 1) with independent fixation. When it is pressed, the anode voltage + 27 V and the filament voltage of the indicator lamps are turned off.

After the electronic clock is connected to the power grid, the meter triggers can be set to any arbitrary state. To reset the counters to zero, use the S5 button, when pressed, the “Set. 0" seconds, minutes and hours counters are connected to a common bus having zero potential. At the same time, the inputs of R microcircuits D4…D8 The frequency divider is disconnected from the common bus, which is equivalent to applying a unit level to them, and the frequency divider is also set to zero.

Using a button S4 manual correction of the clock is performed using precise time signals. The correction is made as follows.

Before the start of the sixth signal, press the button S4. In this case, the frequency divider, seconds and minutes counters are set to zero and will remain in until the button is pressed. S4, If before pressing the button S4 at the output of the minute counter there was a level of logical one (the clock was lagging), then at the moment it is pressed, a negative voltage drop will arrive at the hour counter, changing its state by one. If the output of the minute counter was at a logical zero level (the clock was in a hurry), then no pulse is generated at its output and the hour counter remains in the same state. With the beginning of the sixth signal, the button S4 released, and from this moment the countdown will continue.

The electronic clock also includes an alarm clock (see Fig. 1), which includes time preset switches S7…S10, inverters D12,D13, matching pattern D14, waiting multivibrator D11, tone generator D15 and two-stage ULF (transistors V24…V26). When the clock reaches the time set by the switches S7…S10, to all inverter inputs D14 single levels will arrive, and the voltage at its output will drop to zero. Transistor V22 will stop, stop shunting the zener diode V23, and to the bass amplifier from the emitter of the transistor V21 a supply voltage of 4-9 V will be supplied. Simultaneously with the output of the element D15.1 logical unit level will be input 8 element D15.2, and the multivibrator (inverters D15.2,D15.3), generating pulses with a frequency of about 1 kHz. They are briefly interrupted by pulses of a waiting multivibrator (inverters DILI,D11.2), 5 elements arriving at the input D15.3 with a frequency of 1 Hz. The waiting multivibrator is started by falling second pulses from the frequency divider through a differentiating chain C11R17. necessary to extend the duration of the pulses coming from the frequency output. The duration of these pulses is about 5 μs and is not sufficient to directly modulate the oscillations of the main multivibrator. From the release of element 11 D15.3 Oscillator oscillations arrive at the ULF input and are converted by a loudspeaker IN 1 into a tone sound signal interrupted at a frequency of 1 Hz. Potentiometer R22 The volume of the sound signal is adjusted. After 1 minute has passed, the status of the minute counter will change. As a result, the output of the element D14 the logical one level appears, the transistor V22 the voltage at the output of the parametric stabilizer (transistor V21 and zener diode V23), supplying the ULF amplifier will decrease to 0. At the same time to the input 4 element D11.1 and entrance 8 element D15.2 a logical zero level will arrive, disrupting the multivibrators. Turning off the ULF supply voltage is necessary to eliminate noise reproduced by the loudspeaker. If necessary, a sound signal is turned on using push-button switch 53. Diodes V17…V20 serve to protect microcircuit inputs D12,D13 from contact with + 27 V voltage from the minute and hour counters.

The supply voltages necessary for the clock to operate are generated in the power supply (see Fig. 1). On-tion amplifier A1 and transistors V7,V8 The main stabilizer for powering the microcircuits is made. Transistor stabilizer V14 and zener diode V15 designed to power only 217 series microcircuits that require two DC voltage sources. The supply voltage of the operational amplifier, ensuring its normal operation, is created by two rectifiers - the main one (diode

Rice. 5: A - analogue of a counting trigger on AND-NOT elements; b- analogR . S trigger on AND-NOT elements

Transformer 77 is made on an ШЛ16X25 core. Winding I contains 2420 turns of wire PEV-2 0.17, windings II and IV respectively 60 and 306 wires PEV-1 0.23, windings III and V respectively 86 and 12 turns of wire PEV-1 0.8.

In the power supply, instead of P701 transistors, you can use transistors of the KT801, KT807, KT904 series (V9,V14), P702 (V8) or any other powerful transistors, for example the KT802, KT902 series. Transistor V8 installed on a radiator with an area of ​​about 30 cm2. It is fixed on the back wall of the watch, isolating it from the case using a mica gasket and insulating bushings. Transistor V9 also installed on a radiator with an area of ​​5 cm2. U-shaped duralumin plates can be used as radiators.

Electronic clock counters can be assembled on chips of other series, for example 133 and 155, which are JK or D triggers. It is possible to build counters on two- and three-input AND-NOT elements included in 217, 133, 155 and other series of microcircuits. Analogs of triggers with a counting input and triggers with separate installation of states “O” and “1” used in the clock, made on NAND elements, are shown in Fig. 5 a, b. Examples of counters made on JK flip-flops (chips 2TK171, 155TV1, 133TV1) and on D-triggers (chips 133TM2, 155TM2), shown in Fig. 6 a, b.

Rice. 6: A - three-digit register onJK triggers; b- three-bit register circuitD triggers

As digital indicators in electronic watches, you can use IV-6 indicators without any changes in the power supply, as well as IV-ZA, IV-8, by reducing the filament voltage to 0.8 V and replacing the zener diodes V10…U 12 on D814A.

Electronic clocks are made on printed circuit boards. When installing microcircuits on a printed circuit board, you should follow the recommendations given in the collection “To Help the Radio Amateur,” vol. 70, 1980, p. 32 and the magazine “Radio”, 1978, No. 9, p. 63.

Setting up an electronic clock begins with checking the correct installation. Then turn on the power and check the output voltages of the stabilizers in the power supply. Trimmer resistor R11(see Fig. 1) set the voltage at the emitter of the transistor V8 equal to 5.5 V. When installing serviceable elements, all other components of the electronic clock should begin to function immediately and do not need adjustment.

When checking the frequency divider, you should keep in mind that the duration of its output pulses is very short and therefore they can only be directly observed using a special oscilloscope (for example, S1-70). The serviceability of the frequency divider is judged by the operation of the first trigger of the seconds unit counter. If the trigger moves from one stable state to another every second of time, then the frequency divider is functioning correctly.

BBK 32.884.19

Reviewer: Candidate of Technical Sciences A. G. Andreev

To help the radio amateur: Collection. Vol. 83 / B80 Comp. N. F. Nazarov. - M.: DOSAAF, 1983. - 78 p., ill. 35 k.

Descriptions of structures, schematic diagrams and methods for calculating some of their components are given. The interests of beginners and qualified radio amateurs are taken into account.

For a wide range of radio amateurs.

2402020000 - 079

IN------31 - 83

072(02)-83

BBK 32.884.19

TO HELP A RADIO AMATEUR

Issue 83

Compiled by Nikolay Fedorovich Nazarov

Editor M. E. Orekhova

V. A. Klochkov

Art editor T. A. Khitrova

Technical editor 3. I. Sarvina

Corrector I. S. Sudzilovskaya

Delivered to set 01.02.S3. Signed for publication on 06/01/83. G - 63726. Format 84X108 1/32.

Gravure printing paper. Literary typeface. High printing. Conditional p.l. 4.2. Academic ed. l. 4.18. 700,000 copies (1st z- 1 - 550,000). Order No. 3 - 444. 35 edition. No. 2/g - 241, Order of the Badge of Honor Publishing house 1?9P0, Moscow, I-110, Olympic Avenue. 22 The main enterprise of the republican production association "Poligrafkniga". 252057, Kyiv, st. Dovzhenko, 3

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 the 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.

Literature

Good evening, Habrazhiteliki.
Many people were interested in my idea of ​​a clock using vacuum fluorescent lamps.
Today I will tell you how this watch was created.

Indicators

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

Drivers

Printed circuit board

power unit

Subsequently, I replaced the transformer with a pulse one. I recommend using a power supply for halogen lamps at the lowest power as a basis. All that remains is to wind the windings to the required voltages.
It may turn out that for incandescence 1 turn is not enough, but 2 is too much. Then we wind 2 turns and place a current-limiting resistor of 1-5 Ohms in series

Here is an “electronic transformer” with the lid open

I can suggest the option of making a power supply from a faulty energy-saving lamp. I described it, if anyone is interested, take a look.

Firmware

That's all.

P.S. The material may contain spelling, punctuation, grammatical and other types of errors, including semantic ones. The author will be grateful for information about them ©

UPD: Upon request, I'll add a couple more photos.