Schematic diagrams of clocks on K176 series microcircuits. Electronic clocks based on integrated circuits of the K176 series. Changes in the scheme

IMPLEMENTATION OF ELECTRONIC CLOCK ON K176 SERIES CHIPS

9.

SIMPLE SCHEMES ELECTRONIC CLOCK ON K176 SERIES CHIPS

The simplest table or wall clock. The block diagram is shown in Fig. 30. The clock contains a minute pulse sequence generator, counters, decoders and digital indicators for minutes and hours.

The initial time setting is carried out by applying pulses with a repetition rate of 2 Hz to the input of the tens of minutes counter. Setting the “zero” is carried out by applying a positive differential to the pulse generator dividers and to the minute unit counter. 10) Thus, precise setting of the clock time is possible every 10 minutes. When the readings corresponding to 24 hours are reached, the units and tens of hours counters are set to zero by a separate circuit. 6) The schematic diagram of the clock is shown in Fig. 31. 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 watch uses pulse sequences with repetition rates: 1/60 Hz (output 4) - to ensure the operation of the minute unit counter, 2 Hz (output

- for initial time setting, 1 Hz (output 5, 6 - for the “flashing” point. 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. Variants of such generators are discussed in § 5. 2) Counters and decoders of minute units and hour units are made on K176IE4 microcircuits, which provide counting to ten and conversion of binary code into a seven-element code of a digital indicator. 4) minute and hour counters are connected in series.

Rice. 30. Block diagram of the simplest table (wall) type clock

Rice. 31. Schematic diagram of the simplest table (wall) type clock

Installation of 0 dividers of the K176IE12 microcircuit and the K176IE4 microcircuit of the minute unit counter is carried out by applying to the inputs 5 a 9(for K176IE12 chip) and to the input 5 (chips K176IE4) positive voltage 9 V with button S 1 through a resistor R 3. The initial setting of the time of os-steel counters is carried out by applying to the input 4 tens of minutes counter using the button S 2 pulses with a repetition rate of 2 Hz. The maximum time for setting the time does not exceed 72 s.

The installation circuit for 0 counters of units and tens of hours when the value reaches 24 is made using diodes V.D. 1 And V.D. 2 and resistor R 4, implementing the logical operation 2I. The counters are set to 0 when a positive voltage appears on the anodes of both diodes, which is only possible when the number 24 appears. To create the “flashing dot” effect, pulses with a repetition rate of 1 Hz are sent from the output 4 K176IE12 microcircuits are supplied to the hour unit indicator point or to the segment G 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.

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 pin numbers of the most common digital luminescent indicators and the corresponding microcircuit pins are given in Table. 1. The designation of indicator segments in Russian and Latin letters is shown in Fig. 31.

Table

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. The transformer and rectifier are used from the PM-1 power supply, intended for children's electrified toys. An additional capacitor is installed C4 and a winding is wound to power the incandescent circuits of the cathodes of the lamps. 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. C4 Capacitor

with a capacity of 500 μF, in addition to reducing supply voltage ripple, it 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 battery with a rated voltage should be connected in parallel with the capacitor. 7.5 - 9 V.

An electronic stopwatch can be assembled according to the clock diagram shown in Fig. 30. The only difference is that the generator produces a second sequence of pulses, as well as in the setting circuit 0. The stopwatch can have any number of digits, but in most applications up to 10 minutes is sufficient, which is provided by three counters and three indicators.

The schematic diagram of the stopwatch is shown in Fig. 32. The second pulse sequence generator is made on an integrated circuit IMS1 K176IE5 and quartz at a frequency of 32768 Hz. Pulses with a repetition period of 1 s are supplied through a switch S.I. 4 in the "Start" position to the input microcircuits IMS2, which provides pulse counting up to ten and indication of units of seconds. Next, tens of seconds and units of seconds and units of minutes are counted and indicated (microcircuits IMSZ, IMS4). In the “Stop” position, the arrival of second pulses to the input IMS2

stops and the indicators display the number of seconds and minutes that have passed since the stopwatch started. S 2 When you reset the switch to the “Start” position, the contacts R All counters of the sec-on counter circuit are automatically set to zero.R 4. To do this, a reset pulse generated by the chain S 1 And S 2 3, C4,

Then the counting of seconds begins. As switches

a double toggle switch MTDZ, a double push-button switch PDM-2-1 or any button with two pairs of contacts for closure can be used.

A car clock can be made according to a similar design and will differ only in the type of digital indicators and power supply. The schematic diagram of a car clock is shown in Fig. 33.

Rice. 33. Schematic diagram of a car clock

In this circuit, the filament circuits of the cathodes of the lamps are powered from the constant voltage of the vehicle’s on-board network. A voltage of 1.2 V is obtained using a quenching resistor with a resistance of 60 Ohms. The lamp grids are powered in parallel through a resistor R 8. The 9 V voltage for powering the microcircuits is created by a voltage stabilizer V.D. 3, R 5, whereby the common wire of the microcircuits is connected to the cathode of the zener diode.

The remaining elements (minute pulse generator, zero setting, time setting, zero setting at 24 hours) are similar to the elements installed in the clock shown in Fig. 31. Structurally, the clock is made on a foil getinax board measuring 90X50 mm. Digital indicators are installed perpendicular to the board. The lamps are covered with thick black paper with a hole measuring 20xx60 mm so that only the displayed clock digits are visible. Then the clock is installed in the car dashboard. And S 2, Separate buttons are attached to the bottom of the shield S.J. as well as a toggle switch for turning on the indication

S3.

Since when the indication is turned off, the clock consumes less than 1 mA, then during regular use of the car (for example, in the summer), it is advisable not to turn off the clock completely, but only turn off the indication. In this case, time will be saved.

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

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).

Specialized clock chip K176IE12. This microcircuit contains a multivibrator and two counters, with the help of which you can obtain a set of stable pulses with a frequency of 1 Hz (period - 1 second), 2 Hz, 1/60 Hz (period - 1 minute), 1024 Hz, and also four pulse signals with a frequency of 128 Hz, phase-shifted relative to each other by a quarter of a period. A typical connection circuit for this microcircuit is shown in Figure 2 (for simplicity, the power circuits are not shown, but the plus power supply must be supplied to the 16th pin, and the minus to the 8th pin).

Since the microcircuit forms all the main time periods for an electronic clock, in order to ensure high accuracy, the frequency of its master multivibrator is stabilized by a quartz resonator Z1 at 32768 Hz. This is a standard watch resonator; resonators at this frequency are used in almost all electronic watches of domestic and foreign production.

Trimmer capacitors C2 and C3 may be missing; they are needed to very accurately set the clock rate. Pay attention to the resistance of resistor R1 - 22 Megaohms; in general, the resistance of this resistor can be from 10 to 30 Megaohms (10-30 million Ohms)

From the output of the multivibrator, pulses through the internal circuits of the microcircuit arrive at its first counter. The pulse diagrams at its outputs are shown in Figure 2 below. It can be seen that the output S1 has symmetrical pulses with a frequency of 1 Hz, that is, a period of 1 second. Pulses from this output can be applied to the input of the seconds counter. Pulses with a frequency of 128 Hz serve for dynamic indication, but in this lesson we will not study dynamic indication.

The second counter of the microcircuit (upper) has a division factor of 60, and it is used to receive pulses with a frequency of 1/60 Hz, that is, pulses following a period of 1 minute. Pulses with a frequency of 1 Hz (seconds) are supplied to the input of this counter (pin 7), it divides their frequency by 60 and its output produces minute pulses.

Fig.3
The schematic diagram of an electronic watch is shown in Figure 3. The D5 chip is a K176IE12 chip; in this watch it is used only as a source of second and minute pulses. The watch is built according to a simplified scheme - no indication of seconds, only minutes and hours. The role of the seconds indicator is performed by two LEDs VD3 and VD4, which blink at a frequency of 1 Hz.

Push-button switches S1 and S2 are used to set the time, press S1 and the minute counter readings will change at a frequency of 1 Hz, press S2 and the hour counter readings will change just as quickly. Thus, with these buttons you can set the clock to the current time.

Let's consider the operation of the circuit. Secondary pulses from pin 4 of D5 are supplied to the input of its counter with a division factor of 60 through pin 7. At the output of this counter (pin 10), pulses are obtained that follow with a period of one minute. These pulses, through the contacts of the unpressed button S1, arrive at the input C of the counter-decoder D1 - K176IE4 (see lesson No. 10), which counts to ten.

Every ten minutes, a full transfer pulse is generated at the output P of this counter. Thus, it turns out that the pulses at the output P D1 follow with a period of 10 minutes. These pulses are sent to the input of the counter D2 - K176IEZ (see lesson No. 10), which only counts up to 6.

As a result, both counters D1 and D2 count, taken together, up to 60, and the pulses at the P output of counter D2 will follow with a period of one hour. And indicators H1 and H2 will, respectively, show units and tens of minutes.

Thus, at the output P D2 (pin 2 D2) we get pulses that follow with a period of one hour. These pulses, through the contacts of the S2 button, which is not pressed, are sent to the input of the hour unit counter made on the D3 - K176IE4 chip. From the output P D3, pulses with a period of 10 hours are sent to the tens of hours counter on the D4 chip - K176IE3.

These two counters, together, could count up to 60, but there are only 24 hours in a day, so their total count is limited to 24. This is done in this way: as we know from Lesson No. 10, the K176IE4 microcircuits have pin 3, on which a unit appears at the moment when the number of pulses received at input C of the counter reaches four. The K176IE3 microcircuit (lesson No. 10) has the same pin 3, but a 1 appears on it at the moment when the second pulse arrives at input C of this microcircuit.

It turns out that in order to limit the count to 24, you need to apply a logical one to the R inputs of all counters at the very moment when there are ones at pins 3 of both counters D3 and D4. For this purpose, a circuit assembled using two diodes VD1 and VD2 and resistor R5 is used. The logical level at the R input of the counters depends on the ratio of the resistances of resistor R5 and diodes VD1 and VD2.

When there is a zero at pin 3 of at least one of the counters D3 and D4, at least one of these diodes is open and it, as it were, closes the R input to the power supply minus, and therefore a logical zero is obtained at the R inputs. But when there are ones on pins 3 of both counter D3 and counter D4, then both diodes will be closed, and the voltage from the positive of the power supply through R5 will go to the inputs R of the counters and set them to zero.

The time is set using buttons S1 and S2. When S1 is pressed, input C of counter D1 switches from pin 10 of D5 to pin 4 of D5, and instead of minute pulses, second pulses are sent to input D1, as a result, the readings of the minute indicators will change with a period of one second. Then, when the required minutes are set in this way, S1 is released and the clock works as usual.

The current clock time is set in the same way using S2. When you press S2, input C D3 switches from output P D2 to output S1 D5 and instead of hour pulses, second pulses are sent to input C D3.

To power the watch, use a network adapter from a game console, or another source with a voltage of 7-10V. The VD5 diode is used to protect microcircuits from improper connection of the source.