Homemade locator from a Chinese alarm clock. Simulator of a security alarm for a country house. For the "power supply improvement" circuit

Electronics in everyday life

Radioconstructor, 2000, No. 5, p. 30

Chinese alarm clocks have come into our everyday life as a fairly accurate and, most importantly, not expensive device. Many people have a question: is it possible to do this so that Some electronic device was turned on by the alarm or just lighting?
The answer is, of course you can! After all, in essence, an alarm clock contains a sound emitter that receives electrical impulses, and these impulses can even be forced to turn on an electromagnetic relay.

Scheme option actuator for Chinese alarm clock shown in the figure

The scheme involves the use of two alarm clocks - according to a signal, one relay turns on, and according to a signal from the other, it turns off. In principle, if the option to turn it off is not necessary, then the circuit can be simplified by using just one alarm clock B2
The principle of relay operation is based on the hysteresis effect of the relay itself - if a fairly significant current is required to start the relay, then much less current is needed to keep it in the on state.

At first glance, the relay should be permanently closed - after all, it is constantly connected to the “plus” of the power supply and to the “ground” through resistor R3. In fact, the current passing through resistor R3 will not be enough to trigger the relay. In order for it to work you need to give it a little push. The role of the push in this case is performed by transistor VT4. When a signal appears from alarm clock B2, pulses amplified by transistor VT2 will arrive at its base, it will begin to open and the relay will be connected directly to ground.
Thus, to trigger the relay, pulses coming from the alarm clock are used when a signal appears, and to keep the relay in the on state, the current passing through resistor R3 is sufficient.

Turning off the relay works in the same way: when the alarm clock B1 turns on, transistor VT3 will begin to open, but it will begin to briefly short-circuit the relay winding and it will turn off.

Antique clocks are now rare, but you can still find them at train stations, bus stops, and sometimes just on city streets. Some of them are more than half a century old, and they appeared at a time when most control circuits were created using relays. But nevertheless, even in such ancient devices the possibility of remote configuration and synchronization was implemented!

After reading the article, you will learn how the clock networks of the past were structured and how you can revive the ancient technology using Arduino.

One day I was approached with a very interesting request - to restore the functionality of an antique watch from the 60s. They didn’t look very presentable and looked suspiciously like a closet door. At first glance it seemed like it was a handicraft. But in the lower right corner the inscription “Strela” was proudly displayed, from which it followed that the model was factory.

What immediately attracted attention was the mechanism, or rather its complete absence. On the back of the watch there is a hand drive, which is a strange motor with a gearbox.

The motor, although similar to a stepper, has only two outputs from one single winding. The gearbox is made of brass and its gear ratio is 1:12, and thus it turns out that the engine rotates the minute hand, and the hour hand simply follows it.

It was experimentally found that if 24 volts of direct current is applied to the motor winding, the minute hand makes one step. When changing the power polarity, the arrow takes another step. Obviously, the control part of this entire electromechanical system is missing. A little look into history will help you understand where it went.

In the 60s, when electronics was just getting on its feet, various institutions, organizations and factories used hybrid electromechanical watches to display time. First of all, the need for them arose in the field of passenger transport - for more efficient dispatching of train, tram and bus routes.

A piece of photography by S.I. Akhmerov from a photo album of 1962, Novosibirsk. The clock hanging on the pole is part of the trolleybus system - drivers check the time using it.

It was required that several clocks have the same readings, despite the fact that they could physically be quite far from each other, for example, within a transport route or in a building. This problem was solved as follows:

Illustration from the book by N.V. Sidorov “Operation of electric clock installations”, 1962.

The picture shows almost the entire range of devices that could be part of the watch network, and as it becomes clear, I got a secondary watch. The structure of the network is quite simple: the center is the so-called electroprimary clock, which produces alternating multi-polar pulses once a minute. Group relays, together with batteries, serve as repeater repeaters, allowing devices to be distributed over long distances. Since the current consumed by the relay winding is less than that of clockwork drives, the losses associated with increased resistance in long wires will be less. The batteries are used as local power sources for the secondary clock.

It is clear that if there are secondary clocks, then you can try to find the primary ones. Unfortunately, the inspection of the building where the supposed clock network lay did not yield any particular results and the most delicious piece of the system was not discovered. But in the literature of that time the principle of their operation is very well described:

These watches represent a very interesting link in the evolution of technology. They still use well-established methods for measuring time intervals quite accurately using the oscillations of the pendulum, which is the heart of any mechanical watch. But here it is the heart that drives electricity. Approximately every few oscillations, the pendulum closes the power supply circuit of the electromagnet, giving it a new impulse to swing. The rocker arm to which the pendulum is connected, swinging from side to side with the help of small and large pawls, rotates the ratchet wheel. The meaning of this design is that no matter which direction the pendulum moves, the wheel will rotate in only one direction. It has 80 teeth, and with a pendulum oscillation period of 1.5 seconds, it makes half a revolution in one minute. Then the ebonite lever installed on the same wheel comes into play - it alternately closes the necessary contact groups:

And the adjustable key allows you to send impulses manually. By shaking its handle, you can change the time on all clocks on the network at once!

Resistances in the circuit also play an important role - the designers of the past did not spare the energy spent on heating the air, because thanks to the resistances, sparking on the contact groups is reduced, which leads to increased reliability and durability of the device (in those days more attention was paid to these factors).

Now, having understood the principle of operation of the clock network, it was possible to safely make a simple device that emulates the primary clock, especially since with the help of modern technologies it is as easy as pie. But this story would be incomplete without one more thing, which, in my opinion, turned out to be even more interesting than the electric primary clock:

This nondescript-looking box turned out to be another secondary watch from the same watchmaking network, but not as simple as the first. There is a very interesting mechanism inside:

On the door behind the dial there is an electromagnet that moves the minute hand. The sentry, as in the previous case, is connected to it by a gearbox. In addition to all this there is a large gear, numbered from 1 to 24, and with a lot of holes for pins (something like pressure feet) that can be screwed into it. Fuses, resistors and an old relay are fixed inside the case. All together this forms a very intricate scheme.

Turning to the literature helped to understand that this is nothing more than a software clock. Using pins screwed into a large gear, you can set the time to turn on/off any electrical load at a certain time.

The mechanism has its own adjusting key, which allows you to adjust the watch manually and is connected to the anchor. Depending on the polarity of the voltage on the electromagnet, the armature is attracted in one direction or the other. The rocker converts translational motion into rotational motion. And the gears of the mechanism are designed so that the large program wheel makes one revolution per day, and the five-minute and weekly ones - in accordance with their names. The program and week wheels have holes for pins, which close the necessary contacts when the wheel is turned. The accuracy of this “alarm clock” is five minutes. On the watch I received, the pins were set for the times: 8:00, 12:00, 13:00 and 17:00 and for all days except Sunday. This means that at one time this clock notified plant workers about the beginning of a shift, lunch and the end of the working day.

The operation of the mechanism involves closing the contacts for a full minute. Of course, such a long signal would irritate everyone, so components in the watch case ensure that the signal stops after a certain time. In accordance with the technologies of that time, a thermogroup is used for this case - two contacts in contact, one of which is bimetallic (in the photo to the left of the relay). When current flows through the contact, it heats up and opens due to the bending of the contact. This is another reason why accuracy is measured in minutes - the thermal group must have time to cool down before the next operation. The opening time can be roughly adjusted using an adjusting screw.

So, the circuit emulating the primary clock will look like this:

It uses a 24V DC switching power supply, two relays and the Arduino controller itself. The 5V relay serves as a kind of galvanic isolation and closes the 24-volt relay, which in turn switches the power to the opposite polarity. This mode of operation differs from the usual one, since the primary clock produced pulses, but here the voltage to the clock drive is constantly supplied. This solution allows you to simplify the circuit without compromising work.

The sketch for adruino is as simple as blinking an LED:

View code

void setup() (
pinMode(2, OUTPUT); // program pin two as output
}

Void loop() (
digitalWrite(2, HIGH); // enable relay
minute(); // wait fifty seconds

digitalWrite(2, LOW); // turn off the relay
minute(); //wait fifty seconds
delay(9535); //adjustment value, approximately 9.5 sec
}

Void minute()
for(int i=1;i<=5;i++){
delay(10000);
}
}

However, there are some subtleties related to the fact that a minute on Arduino is not a minute of real time at all (this is due to the quartz resonator, clock cycles, as well as the inertia of the relay, and this is a completely different story), so it’s easier to select the delay() value manually : by noting the time period and calculating the error. Then make an amendment to the value of the trim value. This way I was able to set my watch to an accuracy of about a minute per day. Of course, we could do better, but it wasn't necessary.

Assembled circuit: the five-volt relay has gone through a lot in its life, so I had to fill it with silicone glue.

For better or worse, now the clock network turned out to be unnecessary, so the considered clocks will continue to operate in the form of ordinary self-sufficient devices that everyone is accustomed to. Just like half a century ago, they will count down labor moments and serve as a reminder of a bygone era, where a lot of interesting things were hidden in seemingly simple things.

Tags:

watch
clock network
Arduino
relay
rarity

Add tags

This probe is designed for express testing of low-frequency quartz resonators, for example, clock resonators at a frequency of 32768 Hz, in addition, it can be used as a generator of stable pulses with a repetition rate of 0.5 and 1 Hz.

The device uses an electronic module from an inexpensive electromechanical Chinese alarm clock with quartz frequency stabilization. As a rule, a large percentage of such alarm clocks, due to wear and tear of the mechanical components, work for no more than two years, while the electronic components remain in good working order. On the printed circuit board of such an alarm clock you can find only three elements: a quartz resonator, an electromagnetic sound-emitting capsule and a packageless microcircuit. Interestingly, the cost of analogues of these three elements in retail may be higher than the cost of the entire alarm clock. A unique feature of such modules from electromechanical and electronic clocks is that they operate at a supply voltage of 1.5 V or less, which is not available for common CMOS microcircuits.

Fig.1

In the proposed device, the electronic module from the MV alarm clock is powered by a voltage of about 1.7 V, which is supplied to it from a parametric stabilizer made on transistor VT1, diodes VD1-VD4 and resistor R1 ( Fig.1). This module has two outputs, to which the stepper motor windings were previously connected. If we take the “minus” of the power supply as the common wire, then relative to the common wire, short pulses of positive polarity are alternately present at these outputs, following with a frequency of 0.5 Hz. In an alarm clock, this makes it possible to move the second hand every second, causing it to make one revolution around the dial every 60 seconds. The quartz resonator ZQ1 and the sound-emitting capsule BF1 from the module were moved to the main printed circuit board. Using microswitch SB1, you can switch the generator to work either with the quartz being tested, or with ZQ1 installed on the board as a control. If the quartz resonator being tested is working properly, then its operation is monitored by alternating flashes of the control LEDs HL1, HL2 and by the intermittent trills of the sound emitter BF1. The absence of light and sound signals may indicate a malfunction of the quartz resonator, and a changed tone of the BF1 sound may indicate a significant frequency deviation.

Using transistor switches VT2, VT3, you can obtain short pulses of negative polarity from the device with a frequency of 0.5 and 1 Hz and an amplitude equal to the supply voltage of the device. Pulses with a frequency of 1 Hz are generated using an adder on diodes VD5, VD6 and transistor VT4. Since the device can be powered with a voltage of +3.3 V...+9 V, it can be used for setup and accelerated prototyping of devices on both CMOS and TTL/TTLSH microcircuits. Resistor R6 pulls up the log level. “1” at the device output to the supply voltage level. The C1L1C2 LC filter eliminates the mutual influence of the probe and the target structure connected to a common power supply. Resistor R2, additionally installed on the alarm circuit board, reduces the excessive sound volume of BF1, in addition, it reduces the direct current through the “sound” output of the microcircuit if the operation of the IC generator was stopped when voltage was present at the BF1 terminals.

Construction and details

The device can be mounted on a mounting plate measuring 70x30 mm ( Fig.2). Capacitor C4 and resistor R2 are soldered onto the alarm clock circuit board. Diodes VD5, VD6 are also installed on it. The design can use small-sized general-purpose resistors of any type or surface-mount SMD resistors. Non-polar capacitors such as K10-17, K10-50 or analogues, the rest - K50-35, K53-19, K53-30 or their analogues. The use of special low-profile capacitors will reduce the mounting height, which will simplify the selection of a housing for the probe, which, for example, can be part of a case for a compact audio cassette.

rice. 2

1N914 diodes can be replaced by any of the 1N914, 1N4148, KD512, KD521, KD522, KD103 series. Instead of 2SC3330 transistors, you can use 2SC2458, 2SC3199, 2SC2668, KT315. The pinout of these transistors is the same. LEDs can be installed of any type for general use, for example, from the KIPD21, KIPD40, AL307 series. As a socket for the tested resonators, we used a socket for a microcircuit, the design of which is designed for a large number of installation and disassembly operations. A micromodule with a microcircuit is suitable for any faulty alarm clock in which the stepper motor makes 1 cycle per second. Alarm clocks with a smooth movement of the second hand are not suitable for this device. There are no standards for the location and number of contacts on the printed circuit board for such alarm clocks, so it is advisable to mark them before removing the board from the alarm clock.

As seen in photo, the micromodule contacts responsible for starting the sound generator are closed by a drop of solder. Therefore, the sound signal of the “Chinese” module will sound continuously, the domestic one - 1 minute after each closure of these contacts. If you need to mute the sound, you can solder a microswitch to these contacts. Micromodules from such alarm clocks can find many other applications. For example, short light flashes on airplane models look very impressive, reminiscent of the beacons of airliners flying across the night sky. Also, among other things, clock microassemblies can be used as ready-made generators for various time relays, automation devices, home-made entry-level measuring instruments, autonomous both master and slave clocks.

Literature

Butov A.L. Indicator from a Chinese alarm clock // Electrician. - 2008. - No. 11-12. - P.80-81.

In some cases, in electronic wristwatches, the volume of the signal or voice notification about the current time may not be sufficient. In this situation, we offer readers a device that increases the volume of such signals. The device is shown in the figure, its basis is an ultrasonic sounder on a specialized DA1 chip. The DC mode is determined by resistors R2 and R3, and the gain is determined by the ratio of resistors R5, R4 and is approximately 10. A dynamic head BA1 is connected to the output of the ultrasonic sounder; the volume of the signal can be adjusted with a variable resistor R1. The device is connected to a wristwatch instead of or in parallel with a piezoelectric sound emitter. If the case is metal, the common wire of the device is connected to it. Timer circuits for periodically switching on the load The device uses MLT or similar resistors, a variable resistor - SP-1, SPO, SP4, capacitors C1, C4 - K10-17, oxide capacitors - K50-35 or imported ones. The TDA2030 chip is replaceable with the TDA2040, the dynamic head is any power of 0.5...5 W with a voice coil with a resistance of 4...8 Ohms, for example, 0.5GDSH-2, 2GDSH-16. You can also use a speaker system with appropriate impedance. The device must be powered from a stabilized source with an output voltage of 12 V, providing a load current of up to 0.5 A. All parts, except the dynamic head, are placed in a housing of a suitable size using wall-mounted mounting. A correctly assembled device does not require adjustment. S. IRGALIEV, Tashkent, Uzbekistan. ...

For the "Pulse alarm backlight" circuit

When you wake up at night or early in the morning, the first thing you want is to know the time so as not to oversleep on your way to work or school. The room is dark, and you don’t want to get up to turn on the light. The proposed device is designed to facilitate this task (Fig. 1). The dial and hands are illuminated by the HL1 LED, which has a very high brightness (3.5...4.5 cd) at a current of approximately 20 mA. The device turns on automatically when it gets dark, when the resistance of the photodiode VD1 increases. Transistor VT1 closes, the generator, made on transistors VT2, VT3, starts working. Its advantage is that during the pause between pulses both transistors are closed, so the current consumed from the power source is minimal. Pulse duration (lighting alarm clock LED HL1) - 4 s, pause duration 26 s. As practice has shown, this is completely enough to see an hour. Catalog printed circuit board gold digger But if you wish, you can set a mode more convenient for you by selecting resistor R3 or capacitor C2. In addition, when the device operates in this way, a small current is consumed from the power battery GB1, which increases its service life. When the room is light, the current consumption of the device does not exceed several microamps, so there is no supply voltage switch. Resistors and capacitors can be any small-sized (C 1 any ceramic or film). Transistors are any of the series indicated on the diagram. Instead of the FD256 photodiode, FD256A, FD256B or a small-sized high-resistance photoresistor, for example, SF2-8, SFK-1M, are suitable. We can replace the LED indicated in the diagram with any one with high luminous intensity. The GB1 battery can be composed of galvanic cells or small batteries connected in series.Details...

For the "TALKING CLOCK" scheme

Consumer electronics TALKING CLOCK V. DENISOV 247400, Gomel region, Svetlogorsk, Parichskaya st. 14-10.I have long dreamed of a “talking” watch, but I could not flash the ROM. Therefore, I used a "TALKING WATCH" wrist watch (made in China). "speaking" is shown in Fig. 1. The time signal sounds independently in each room and in the corridor. For this purpose, dynamic heads BA1...BA4 are used. The amplifier is assembled on four transistors VT1...VT4. Scheme switching (Fig. 2) is assembled on a relay type RES 22. It works scheme So. When you press the SB1 button, relay K 1 is activated and is blocked by its contacts through the normally closed contacts of other relays (K4.2, KZ.2, K2.2). Contacts K 1.1 turn on the loudspeaker BA1 "Hall", and at the same time relay K5 is activated (but is not blocked). Turn relay on a thyristor circuit. Contacts K5.1 turn on the clock speech synthesizer. The time signal sounds in the selected room. The rest of the rooms are silent. As soon as you press the SB2 (SB3, SB4) button, the closed relay K1 turns off, and the other one (K2...K4) turns on. In the bedroom, you can put a variable resistor in series with the VAZ to reduce the volume (not shown in the diagram). Instead of internal batteries, it is better to put two external AA batteries or others with a total voltage of 3 V. The power supply is any with output voltages of 5 V and 20 V. Disadvantage of the circuit is that at a certain point in the room you need to lay 4 wires (2 wires for the button, 2 for the loudspeaker). The most convenient way is to use a telephone wire (of the “noodle” type) and hide it under the baseboard...

For the diagram "Power supply for electromechanical watches of the Slava type"

With modern battery prices, it is most profitable to power electromechanical watches of the “Slava” type from the mains. Especially if they are built into furniture, for example, in the kitchen. Previously published circuits for such power supply are mostly transformerless; such power supply circuits are dangerous, since the mechanism is under mains voltage, so it is better to use a transformer power supply (see figure). Scheme no originality. It includes a parametric current stabilizer CI, R1, I winding T1 and a 1.5 V voltage stabilizer on VD5, VD6. The author has had this power supply paired with a small AA battery in his kitchen for more than 10 years. It is needed to ensure movement in the event of a power outage. The entire power supply fits completely into the battery compartment together with the “finger”. Transformer T1 is a transition from the Speedol radio receiver (VEF). O.G. Rashitov, Kyiv....

For the scheme "MELODIC CALL FROM... A WATCH"

Consumer electronics MELODIC CALL FROM... WRIST K.KULIKOV, 443072, Samara-72, 18 km of Moskovskoe highway, 13-61l I had an imported electronic wristwatch in a metal case with a faulty indicator. Titles hours there are many of this type (for example, "Montana"), but they are all the same. With the current time on the indicator, the melody is turned on by constantly pressing the “AL.TM” button and briefly pressing the “DATE” button. This principle is implemented in the call. Battery hours replaced with ingredient A343, it lasts for several years. It is best to solder the element, because... salt often appears on the “-” and it oxidizes. Instead of a piezo emitter, a load must be turned on - capacitor C1 type KM (between the housing hours and “spring”). An amplifier is added on a transistor type KT829 (KT827) with a large VST, the load of which is a speaker of 0.5 W, 4 Ohms. And for some hours The volume turned out to be insufficient, so I had to buy an additional amplifier on the KT3102D. The power supply is a simple 15 V rectifier with a permanent connection of the primary winding to the network. Because Some melodies have a long sound time, which is undesirable for a call; it is supplemented with a time relay that limits the sound time to a few seconds. Scheme borrowed from . Setting up a time relay - there. Literature 1. Radio.-1990.-N 2. p.32.Amateur Radio 7/96...

For the "Simple electric musical bell" circuit

The proposed musical ringer plays several melodies. Can be used as an alarm clock. The “heart” of the call can be the MONTANA alarm clock. You need to take the clock out of the case, unscrew the screws holding the board to the indicator, solder the pins using thin conductors according to Fig. 1 and secure the board back in place. These pins connect the clock to the circuit shown in Fig. 2. Operation of the circuit and purpose of the elements. The audio amplifier is made on elements R2, VT1, VT2. Trimmer resistance R1 sets the sound volume. Capacitor C1 prevents the amplifier from consuming power in standby mode. The diode assembly VDl, VD2 is necessary to simultaneously supply a positive pulse to pins 1 (DATE) and 2 (ALTM). The fact is that you can forcefully turn on the melody in the watch by simultaneously pressing two buttons DATE and ALTM. The watch does not block melody playback. Consequently, if you press the bell button frequently, the change of melodies will occur randomly. To prevent this from happening, elements SZ, VD3, R3, VD4, C4 were introduced into the circuit. Simple current regulator When you press the bell button (contacts Kl, K2), a positive pulse is sent through the capacitor SZ and the diode assembly VDl, VD2 to terminals 1, 2 o'clock. After the melody starts playing, the sound frequency enters the capacitor SZ and charges it. A charged capacitor does not transmit a positive pulse from contact K1. Thus, a call while a melody is playing will not respond to pressing the Kl, K2 button. After the end of the melody, the discharge circuit VD3, R3 discharges the capacitor SZ, preparing it to receive the next signal. If you do not release the bell button (Kl, K2), the SZ capacitor will not discharge and the bell will go into standby mode. There will be no continuous playback of the melody. Capacitors C2, C5 protect the call from false alarms, which can be caused by pulsed noise induced into the wire connected to pin K1. Food...

For the circuit "Electronic clock power supply circuit from the network"

The technical literature describes units for powering electronic-mechanical alarm clocks from the mains. The blocks that replace the 1.5 V galvanic ingredient contain a rectifier with a voltage stabilizer and a step-down transformer. The stabilizer eliminates drops in supply voltage during rare increases in load at the moment the signal electroacoustic transducer (bell, electric buzzer) is turned on. A step-down transformer is required according to electrical safety standards. I believe that to power electronic-mechanical devices without a signal electroacoustic converter, an electric bell or a buzzer, the power supply unit can be significantly simplified. Due to the negligible current consumption of the clock, it is possible to use a symmetrical transformerless circuit (see figure) with step-down capacitors C1 and C2 of very small capacity (0.033 μF each, 200 V type BGM-2), which make the electrical wires going to the clock safe. Soldering iron underheating diagram What is not in . There may be no stabilization in the unit, since the clock does not have an electric bell or buzzer, and voltage fluctuations in the electrical network are insignificant and do not have a significant effect on the accuracy of the clock. In addition, the periods of decreasing and increasing voltage in the electrical network are approximately equal in length, which causes mutual compensation of slowing down by accelerating it and vice versa. Capacitors C1, SZ and resistor R1 (1 kOhm type BC-0.125 W) can be placed in a special electrical plug plugged into a power outlet, and diodes and capacitor C2 (470 μF 6.3 V type K50-24) can be placed in a dimensional case inserted into the compartment hours instead of galvanic cells. Other options are possible. The required voltage at the output of the block is achieved by specifying the resistance value of the resistor...

For the "Telephone call time counter" scheme

Today, in many cities and towns across the country, time-based payment for telephone calls is in effect. Unfortunately, the subscriber learns about the time spent on calls only from the sent invoice. To be able to control accounts. I propose to make a telephone call duration counter from widely used electromechanical switches powered by one galvanic element of standard size AA (316, “finger”). counter is shown in Fig. 1. The break in the telephone line includes the base-emitter section of transistor VT1, shunted by resistor Rt. The current flowing in the line when the handset is off-hook opens a transistor that closes the power supply circuit of the electromechanical clock. They walk, counting down the time to talk. As soon as the telephone receiver is hung up, the closed transistor opens the power circuit hours and stops counting time. The galvanic ingredient G1, which powers the watch, is conventionally shown in the diagram outside its case. Triac TS112 and circuits on it However, it is by no means necessary to remove it. Enough as shown in Fig. 2, insert between the positive terminal of the element and the contact spring a strip of fiberglass foil on both sides with a thickness of 1 mm or less. A conductor going to resistor R1 and the emitter of transistor VT1 is soldered to the layer of foil in contact with the terminal of the element. to the opposite layer going to the collector of the transistor. MLT-0.125 resistor or other small-sized one. The transistor indicated in the diagram can be replaced by any low-power silicon pnp structure. Both parts can be...

For the "ANSWERING AUTO-RESPONDER WITH TIME" scheme

TelephonyAnswering machine that tells the time Nowadays, “talking” watches in various designs - wrist and table - have appeared on sale in markets and stores. They can be used as an answering machine that tells you the time on departmental and office PBXs. To install an answering machine, you need a separate telephone line, which will be used only to obtain information about the current time. A subscriber who calls the number corresponding to this line hears a voice message from the “talking” clock. device is shown in the figure. The calling signal from the telephone line is sent to the diode bridge VD1. Current begins to flow through the LED of optocoupler U1. The optocoupler transistor opens and the capacitor SZ is discharged through resistor R3. When a low level (below 2/3 of the supply voltage) appears at pin 2 of the OA1 microcircuit, the timer starts and a high level appears at its output (pin 3). Phase-pulse power regulator on CMOS Transistor VT1 opens and turns on relay K1. Contacts K1.1 connect resistor R9 to the line, and the call signal stops. Timer DA1 is enabled in one-shot mode. The pulse duration is determined by the circuit R5R6R7C4. This duration must be selected so that there is a pause between the end of the voice message and the disconnection of resistor R9 from the line. When a high level appears at the output of the timer, diode VD3 closes and charging of capacitor C8 starts through resistor R11. Circuit R11C8 sets a pause before the clock “answers”. Then transistor VT2 will open and bypass the “answer” button on the clock. From the exit hours The sound signal is sent to an amplifier, which is assembled using transistors VT3-VT7. It is described in detail in. Through transformer T1, the signal from the amplifier output enters the telephone line. When the pulse generated by the one-shot device ends, a low level will appear at the output of DA1. IN...

For the scheme "IMPROVEMENT OF THE POWER SUPPLY"

Power Supply POWER SUPPLY UPGRADESCommercially available power supplies Chinese production at several voltages when connected to a player or receiver gives a large background of alternating current, since in the filter after the diode bridge there is only an electrolytic capacitor of 470 μF. I propose a simple modification to the block, which significantly reduces the level of pulsation. Additional parts are placed in the body of the block itself. The improved block does not require any special explanation. It is advisable to install the transistor on a small radiator made of a piece of tin. Voltage switch SB1, after modifying the circuit, gives levels “shifted” by 1.5V. If desired, you can resolder the conductors suitable for SB1 and recreate the correspondence between those indicated on the switch and the output voltages, but then there will be no upper limit (12 V). O. KLEVTSOV, 320129, Dnepropetrovsk, Sholokhov street, 19 - 242. (RL-7/96)...

This watch has already been reviewed several times, but I hope that my review will also be interesting to you. Added job description and instructions.

The designer was bought on ebay.com for 1.38 pounds (0.99+0.39 shipping), which is equivalent to $2.16. At the time of purchase, this is the lowest price offered.

Delivery took about 3 weeks, the set came in a regular plastic bag, which in turn was packed in a small bubble bag. There was a small piece of foam on the indicator terminals; the rest of the parts were without any protection.

From the documentation there is only a small A5 sheet of paper with a list of radio components on one side and a circuit diagram on the other.

1. Electrical circuit diagram, parts used and operating principle

The basis or “heart” of the watch is an 8-bit CMOS microcontroller AT89C2051-24PU equipped with a 2kb Flash programmable and erasable ROM.
Clock generator node assembled according to the circuit (Fig. 1) and consists of a quartz resonator Y1, two capacitors C2 and C3, which together form a parallel oscillatory circuit.

By changing the capacitance of the capacitors, you can change within small limits the frequency of the clock generator and, accordingly, the accuracy of the clock. Figure 2 shows a variant of a clock generator circuit with the ability to adjust the clock error.

Initial reset node serves to set the internal registers of the microcontroller to the initial state. It serves to supply, after connecting power, to 1 pin of the MK a single pulse with a duration of at least 1 μs (12 clock periods).
Consists of an RC circuit formed by resistor R1 and capacitor C1.

Input circuit consists of buttons S1 and S2. The software is designed so that when you press any of the buttons once, a single signal is heard in the speaker, and when you hold it, a double signal is heard.

Display module assembled on a four-digit seven-segment indicator with a common cathode DS1 and a resistive assembly PR1.
A resistive assembly is a set of resistors in one housing:

Sound part The circuit is a circuit assembled using a 10 kOhm resistor R2, a pnp transistor Q1 SS8550 (acting as an amplifier) and a piezoelectric element LS1.

Nutrition supplied through connector J1 with smoothing capacitor C4 connected in parallel. Supply voltage range from 3 to 6V.

2. Assembling the constructor

The assembly did not cause any difficulties; it was written on the board where to solder what parts.

Lots of pictures - the assembly of the designer is hidden under the spoiler

I started with the socket, since it is the only one that is not a radio component:

The next step was to solder the resistors. It is impossible to confuse them, they are both 10 kOhm:

After that, I installed on the board, observing the polarity, an electrolytic capacitor, a resistor assembly (also paying attention to the first pin) and elements of a clock generator - 2 capacitors and a quartz resonator

The next step is to solder the buttons and the power filter capacitor:

After this, it’s time for the sound piezoelectric element and transistor. The main thing in a transistor is to install it on the correct side and not to confuse the terminals:

Lastly, I solder the indicator and power connector:

I connect it to a 5V source. Everything is working!!!

3. Setting the current time, alarms and hourly signal.

After turning on the power, the display is in "HOURS: MINUTES" mode and displays the default time of 12:59. The hourly beep is on. Both alarms are on. The first is set to operate at 13:01, and the second at 13:02.

Each time you briefly press the S2 button, the display will switch between the modes (“HOURS: MINUTES”) and (“MINUTES: SECONDS”).
When you press the S1 button for a long time, you enter the settings menu, which consists of 9 submenus, designated by the letters A, B, C, D, E, F, G, H, I. Submenus are switched by the S1 button, the values are changed by the S2 button. Submenu I is followed by exiting the settings menu.

A: Setting the current time clock
When you press the S2 button, the clock value changes from 0 to 23. After setting the clock, you must press S1 to go to submenu B.

B: Setting the minutes of the current time

C: Turn on the hourly beep
The default is ON – a beep sounds every hour from 8:00 to 20:00. Pressing the S2 button changes the value between ON and OFF. After setting the value, you must press S1 to go to submenu D.

D: Turn on/off the first alarm
By default, the alarm is ON. Pressing the S2 button changes the value between ON and OFF. After setting the value, you must press S1 to go to the next submenu. If the alarm is turned off, submenus E and F are skipped.

E: Setting the first alarm clock
When you press the S2 button, the clock value changes from 0 to 23. After setting the clock, you must press S1 to go to submenu F.

F: Setting the minutes of the first alarm
When you press the S2 button, the minutes value changes from 0 to 59. After setting the minutes, you must press S1 to go to submenu C.

G: Turn on/off the second alarm clock
By default, the alarm is ON. Pressing the S2 button changes the value between ON and OFF. After setting the value, you must press S1 to go to the next submenu. If the alarm is turned off, submenus H and I are skipped and the settings menu is exited.

H: Setting the second alarm clock
When you press the S2 button, the clock value changes from 0 to 23. After setting the clock, you must press S1 to go to submenu I.

I: Setting the minutes of the second alarm
When you press the S2 button, the minutes value changes from 0 to 59. After setting the minutes, you must press S1 to exit the settings menu.

Seconds correction
In the mode (“MINUTES: SECONDS”), you must hold down the S2 button to reset the seconds. Next, briefly press button S2 to start counting the seconds.

4. General impressions of the watch.

Pros:
+ Low price
+ Easy assembly, minimum parts
+ The pleasure of self-assembly
+ Quite a low error (I was a few seconds behind during the day)

Minuses:
- Doesn't keep time after power off
- Lack of any documentation other than the diagram (this article partially solved this disadvantage)
- The firmware in the microcontroller is protected from reading