Programmable control machine. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Clocks, timers, relays, load switches

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To control various kinds of electrical installations in everyday life and at work, it often becomes necessary to repeatedly turn them on and off at certain time intervals. This task is usually successfully solved with the help of digital timers with memory. In the article published below, readers are offered a description of a variant of a device for such a purpose, which can be made independently.

The programmable machine is designed to control network electrical appliances of low and medium (up to 1 kW) power. In everyday life, it can be used, for example, to control a Chizhevsky chandelier or electric heaters in a residential area. The author used an automaton to control a computer that communicates with the BBS at night.

The machine contains two identical independent programmable channels, each of which controls one load. The number of channels can be arbitrarily increased without fundamental modifications to the basic units of the device itself. During its operation, the real time is counted and the current value is displayed in hours and minutes, as well as serial numbers (from 1 to 7) of the days of the week.

The maximum duration of the control program in each of the channels is one day, however, if necessary, the user can enable or disable the execution of the daily program recorded in the memory on any of the seven days of the week. The minimum programmable interval between two events is one minute. An event here refers to the switching on or off of a controlled load. Thus, the maximum number of programmable events is equal to the number of minutes in a day, i.e. 1440. At any time, using the controls, you can change the current states of the loads. Clearing (zeroing) the memory before programming is carried out by automatic enumeration of addresses at the user's command in both channels at once or in each separately.

When programming, the possibility of both address-by-address writing and address-by-address erasing of data in memory is provided. The machine has an AF generator that can give sound signals at the moments of occurrence of each programmed event. When the mains voltage is turned off, automatic switching of the digital (low-voltage) part of the device to power from the backup battery is provided, which allows you to keep a continuous count of time and avoid changes in the current states of the triggers that control the loads.

The block diagram of the automaton is shown in fig. 1. It consists of a counting and indication unit, two identical channel units, electronic relays, and an AF generator that can be connected to any of the channels (in the diagram, for example, to channel 1).

In the counting and indication block, the current time and day of the week are counted, their values ​​are displayed on the indicators, as well as the formation of addresses for the RAM channels.

The control unit sets the counters to the desired position and performs operations with the channel memory. The synchronizer generates counting and control sequences of pulses. The RAM stores the program for managing the state of the loads in each of the channels. Status nodes convert the pulse signals read from the RAM into voltages of a certain logic level, which control electronic relays that switch the mains voltage supplied to the loads.

Schematic diagram of the counting and indication unit is shown in fig. 2. It is an electronic watch. The functions of the source of counting and control sequences of pulses (synchronizer) are performed in them by a specialized clock chip DD12 (K176IE18), containing a quartz oscillator. The following signals are taken from its conclusions: from the pin. 10 - counting minute pulses (1/60 Hz), which, through the shortening circuit on the elements DD1.5, DD1.6, C15, R18 and the elements DD13.4, DD4.3, DD4.2, are fed to the counting input of the counter of units of minutes DD7.1 .one; with pin. 4 - second pulses used to indicate the second rhythm LED HL1; with pin. 11 - pulses with a frequency of 1024 Hz, which pass through the counter-divider into two DD2.2, after which their frequency decreases to 512 Hz; with pin. 6 - pulses with a frequency of 2 Hz, ensuring the blinking of the familiarity of indicators HG1 - HG4 in the mode of setting their readings.

(click to enlarge)

The counting part of the block under consideration is built according to a common scheme with serial connection of counters with specified conversion factors and static indication of their states by seven-segment indicators HG1 - HG5. The address bus AO - A15 is formed from the microcircuits DD7, DD10, DD14 involved in the counting of bits. A feature of the proposed circuitry solution is the ability to quickly change the state of each of the counters by the user, which facilitates writing to the data memory during programming.

The block is controlled by the buttons SB1 - "Installation", SB2 - "Search of familiarity" and SB3 - "Mode". In the initial state on the pin. 6 of the DD6 decoder there is a high logic level, so all its outputs (pin 1, 5, 2, 4, 12, 14, 15, 11) will have low levels that prohibit the passage of setting pulses from the SB1 button to the counters DD7.1, DD7.2 .10.1, DD10.2, DD4.1 through the elements DD5.4, DD9.3, DD11.3, DD16 and allowing the conversion of decoders DD19 - DD3. With a single press of the SB8.1 button, the DD6 trigger goes into a single state, allowing the operation of the DD1 decoder switches, on one of the outputs (pin 5, 2, 4, 12) of which a high level appears, and on the other (pin 14, 15 , 11, 2) - pulses with a frequency of 1 Hz. As a result, one of the four familiarity spaces HG4 - H1 starts flashing at the specified frequency. Using the SB2.1 button, the state of the counter of this familiarity is changed (indicator readings). "Activity" of a particular familiarity depends on the state of the counter DD3 at the time of pressing the button SB2.1. You can change the state of the counter DD2 using the SBXNUMX button. Thus, by sequentially setting the readings of the indicators of each familiarity, you can very quickly set the required time (address on the address bus).

The state of the counter of the day of the week DD14 is set by transferring the state of the counter of tens of hours DD10.2 when setting. It should be noted that it is more convenient to start setting the required indicator readings from a few minutes and end with the days of the week, since the value already set in the higher familiarity will be increased by one by the transfer that can occur when setting the value in the lower familiarity. Button SB5 "Initial setting" is designed for accurate (up to seconds) setting the clock according to the reference time source. At the moment this button is pressed, the internal counter of seconds of the DD12 microcircuit and the counters of units and tens of minutes of the DD7.1, DD7.2 microcircuits are reset.

In addition to the address signals AO - A15, several more control signals are removed from the counting and display unit: from the pin. 4 microcircuits DD3.2 (circuit 1) - short minute pulses, setting pulses from the SB1 button; with pin. 6 microcircuits DD15.3 (circuit 2) - pulses from the SB6 "Record" button, as well as pulses with a frequency of 512 Hz (in the memory clearing mode); with pin. 13 microcircuits DD8 (circuit 3) - a static signal, the high level of which ensures the implementation of the memory cleaning mode.

The memory cleaning mode is set by pressing the SB4 "Clear" button once if the contacts of the SA1 cleaning unlock switch are closed. In this mode, the trigger DD8.2 goes into a state of logical 1, the passage of minute pulses to the counting input of the counter DD7.1 through the element DD13.4 is prohibited, and the passage of pulses with a frequency of 512 Hz through the element DD4.4 is allowed. The result is a count (enumeration of addresses) with a frequency of 512 Hz. Pressing the SB4 button again returns the trigger DD8.2 to its original state of logical zero. At the initial power-up, both triggers DD8 are set to a logic zero state by the C13R11 circuit.

Buttons SB1, SB6 have a contact bounce protection device made on the elements DD1.1, DD1.2, DD15.1, DD15.2. Circuit DD1.5, C15, R18, DD1.6 shortens a long minute pulse from the pin. 10 DD12 chips. Otherwise, this pulse for several tens of seconds in every minute would prohibit setting the state of the counter DD7.1 with the SB1 button.

On fig. 3 shows a schematic diagram of the block of channels of the programmable machine. It also shows a diagram of a device common to both channels, made on the elements DD1, DD2, DD3.1, DD3.2, DD4.1, DD4.2, DD5.1, DD5.2, which generates signals that control the memory.

Now let's consider the operation of the first channel in the recording mode with real-time counting. As shown in fig. 3, the bit A15 is assigned from the address bus AO - A12. The choice of the RAM chip to be accessed depends on its state. Let's assume that at the moment this bit is in a single state and the DD10 chip is selected for the active low level of the CE signal (pin 7 DD8, DD7). Chip DD8 in this case is set to the output in the third state.

(click to enlarge)

When changing the address on the address bus AO - A15 (on the edge of the minute or setting pulse coming from the counting and indication unit), the DD1.1 single vibrator generates a high-level pulse, during which access to the DD7 chip is prohibited in order to avoid reading data from memory at this moment . In the intervals between the pulses generated by the DD1.1 chip, the output of the DD7 chip (pin 7) is set to a logic level corresponding to the data bit read at the current address.

To write a data bit to memory at the desired address, the user must set it on the bus using the control buttons of the counting and indication unit. Then, switch SA3 should select the level intended for recording: logical zero or logical one. If one is selected, an event will be recorded in memory that will occur at the set time. When writing zero, you can, for example, erase an event previously recorded at this address. Next, you need to press the SB6 "Record" button once (see Fig. 2). Along the front of the pulse, which is fed through circuit 2 to the single vibrator DD1.2, the latter will generate recording pulses at its outputs (Fig. 4, a).

From the direct output of the DD1.2 microcircuit (pin 10), the write pulse enters the unit for generating short pulses along the front and along the fall of the write pulse, made on the elements DD2.1, R3, C13, DD2.2, DD2.3. From the inverse output of the DD1.2 chip (pin 9), the write pulse enters the delay node on the elements DD5.1, R4, C14, DD5.2, and then to the pin. 8 memory chips DD7, DD8. The delay time is chosen in such a way that at the moments of signal (pulse) changes, the recording on the pin. 8 of the DD7 microcircuit, access to it was prohibited by those coming to its pin. 10 short pulses with pin. 10 DD2.3 chips. Thus, the necessary conditions are created for the correct operation of the clocked RAM chips KR537RU2 in accordance with the passport mode [1]. After the end of the second short pulse with vyv. 10 microcircuits DD2.3 on pin. 7 of the DD7 chip is set to a logic level corresponding to the data bit just written (Fig. 4, a).

Bits A13 - A15 of the counter of the day of the week (see Fig. 2) are not sent to the memory chips, but are fed to the decoder DD14 as the address of the switched electronic key of the chip. Inputs of electronic keys DD14 (vyv. 14, 15, 12, 1, 5, 2, 4) and switches SA7-SA13 correspond to the days of the week, from Monday to Sunday. If one of the switches is closed on the corresponding day of the week, the high voltage level present at the same time on the pin. 3 DD14 chips, allows the passage of a high logic level from the pin. 7 RAM DD7, DD8 via DD4.3 chip. When the switches are open, the low level on the pin. 3 DD14 chips prohibits the passage mentioned above. The C18R12 circuit generates a high-level voltage trigger switching pulse DD13.1 on the edge of the high-level voltage read from the memory. The user can change the state of the trigger at any time using the SB1 button, controlling it by the presence or absence of the HL3 LED. If programming is carried out with the load connected, then it should be temporarily disabled by switch SA6. Its status is monitored by the glow of the HL4 LED. Whenever a switching pulse arrives at input C (pin 3) of the DD13.1 trigger, a short high-pitched beep is heard in the BF1 phone, generated by a 3H generator on the elements C17, R10, DD5.3, DD3.3.

Before writing programs into memory, it is necessary to clear it, that is, write logical zeros to all available addresses. Enumeration of addresses during cleaning is carried out with a relatively low frequency of 512 Hz (Fig. 4,b), which allows visually (by the absence of blinking of the HL2 LED) and aurally (by the disappearance of the signal reproduced by the BF1 phone) to control the absence of logical units in the memory. It is advisable to repeat the cleaning cycle (enumeration of all time values) 2-3 times. It only takes a few seconds. Switch SA3 must be previously set to position "0". If you want to work with the memory of only one channel without affecting the contents of the memory of another, then you can block the latter from being accessed by moving the corresponding switch SA1 or SA2 "Memory Lock" to the lower position according to the diagram. During the cleaning mode, the load state triggers DD13.1 and DD13.2 in both channels are transferred to a logic zero state by a high level at the R-input (pin 4 and 10). The alarm sound generator, made on the DD6 chip, is connected to the output by the enable input (pin 1 DD6). 3 microcircuits DD11.1 of the first or to the pin. 10 chips DD11.3 second channel. In the case of reading from the high-level memory at a given time, with the SA4 "Alarm Clock" switch closed, an intermittent signal will sound for one minute.

A schematic diagram of the electronic relays and the power supply of the programmable machine is shown in fig. 5. The digital part of the electronic relays is based on the device described in [3]. Triac switches VS1, VS2 are used as power elements of electronic relays, the disadvantage of which is the presence of switching surges and distortion of the sinusoidal current shape when controlling powerful reactive loads. In the proposed device, the load is switched at the moment when the AC mains voltage passes through zero, therefore, when switching purely active loads, it was possible to completely get rid of emissions.

(click to enlarge)

Timing diagrams explaining the operation of the electronic relay unit are shown in fig. 6.

A positive voltage drop coming to turn on the load at input D of the trigger (pin 5 DD2.1) at an arbitrary moment t1 will be transferred to the output (pin 1 DD2.1) only at the moment it arrives at its input C (pin 3 DD2.1 .1.2) a short pulse coinciding in time with the zero crossing of the mains voltage. The presence of a short pulse delay node on the elements DD9, R7, C1.3, DD1 is not mandatory and fundamental, however, it allows you to accurately coincide in time the leading edge of the pulse arriving at the input C of the trigger with the moment the mains voltage passes through zero (dip of the pulsating voltage on pins 2, 1.1 of the DDXNUMX chip).

The use of optocouplers U1 - U4 made it possible to completely decouple the electronic relay unit and the digital part of the machine.

The power supply has two integral stabilizers DA1 and DA2. The first of them provides power to the digital part of the machine. Its input voltage is backed up by a GB1 battery with an automatic turn-on circuit based on diodes VD2, VD3. The second stabilizer is used to power optocouplers, LEDs and seven-segment indicators. The line filter C8L2L3C9 suppresses surges and mains voltage interference.

There are no strict requirements for the element base of the automaton.

The author used OMLT resistors indicated on the power diagrams, oxide capacitors - K50-16, the rest - KM, KLS; buttons SB1 - SB6 (see Fig. 2) and SB1, SB2 (see Fig. 3) - KM1-1; switches SA1, SA2 (see fig. 3) - МТЗ, SA3, SA6, SA15 (see fig. 3) and SA1 (see fig. 2) - МТ1, SA4 (see fig. 3), SA1(cm Fig. 5) - PK4-1, switches "Days of the week" SA7 - SA13, SA16 - SA22 - assemblies of microswitches VDM1-8. The eighth switch in the assembly is used as SA5, SA14 ("Sound"). Any seven-segment LED indicators with a common cathode (it is better to use imported ones, for example, LTS547AP). KT315 transistors with any letter index, BQ1 quartz resonator at a frequency of 32 Hz, BF768 telephone capsule - any resistance of 1 ... 200 Ohms, for example, imported DH300F. Triacs KU30G can be replaced with more powerful ones, for example, TS208-112-16-10, however, the distortion of the sinusoidal current shape when controlling inductive loads will become more noticeable in this case. As electronic relays, you can use the integrated "solid-state relays" D7 or D2410 from IR, in which switching on is implemented by zero mains voltage, and switching off - by zero current through the load [2475].

Transformer T1 should provide an alternating voltage of about 8 V on the secondary winding at a load current of 600 mA. Filter coils L1 - L3 are wound on rings (20x10x4 mm) made of M2000NM-1 ferrite with MGTF 0,5 wire until filled, and coils L2, L3 are wound simultaneously with two wires.

The GB1 uses a battery of six finger cells. The current consumed by the digital part of the device from the battery, in the absence of mains voltage, does not exceed 35 mA.

The machine is placed in a case with dimensions of 265x200x100 mm. On its front panel there are controls and indications, and on the back - sockets for connecting the load. Triacs VS1, VS2 are installed on heat sinks with an area of ​​about 150 cm2, and the stabilizer DA2 is installed on a heat sink with an area of ​​50 cm2.

The counting and indication unit and the channel unit are mounted on separate boards with dimensions of 185x80 mm, the elements of electronic relays (except for triacs VS1, VS2) and power supply (except for capacitors C1 - C3, microcircuits DA1, DA2, battery GB1 and transformer T1) are placed on a common board dimensions 170x80 mm. Capacitors C3-C10 in the counting and indication unit and C2-C10 in the channel unit are soldered between the "common" and "plus power" terminals of the RAM chips, counters and triggers.

With serviceable parts and proper installation, the digital part of the machine starts working immediately. Establishing a counting and display unit is reduced to adjusting the frequency of a quartz oscillator on a DD12 chip with a capacitor C18. When establishing a block of channels by selecting resistors R10, R20, you should set the desired tone of the channel sound generators, and by selecting capacitor C16 - the alarm clock generator. The desired duration of the alarm sounds is selected by the capacitor C15. When establishing a block of electronic relays, resistor R8 should be selected in such a way that low-level pulses at the input of the Schmitt trigger DD1.1 (pin 1, 2) ensure its stable switching. By selecting the resistor R9 in the delay circuit, it is necessary to coincide in time the front of the pulse on the pin. 10 microcircuits DD1.3 with the lower point of the pulse on the pin. 1, 2 microcircuits DD1.1 (Fig. 6).

When starting to program the machine, the following must be taken into account. If the program contains a sufficiently large number of events, it is recommended to build a timing diagram, on which a high level indicates the on state of the load, a low one is off, and drops between levels are events. Having set the desired moments of events, one should write down units to these addresses in the memory, set the current exact time on the indicators, connect the load to the device and set the initial state of the load in accordance with the constructed diagram using the "State Setting" button.

When writing and monitoring data, you cannot use the "Initial setting" button, because when you click on it, the state of the address bus changes, but correct reading from memory at a new address is not achieved.

Analyzing the operation of the machine, it is easy to see that by excluding from the number of addresses supplied to the RAM chips the bits of the counter of units of minutes AO - A3 and including the bits of the day counter A13 - A15, you can get a device programmed for a week. Since, as a result, the bit width of the RAM address bus will become one less, it will be possible to get by with one memory chip per channel, and also to exclude decoders DD14, DD15. The minimum interval between events in this case will become equal to ten minutes, and the maximum number of events in the weekly program will decrease to 144x7=1008.

Literature

1. Baranov V. V., Bekin N. V., Gordonov A. Yu. et al. Semiconductor LSI memory devices. Directory. - M.: Radio and communication, 1986.
2. Shilo VL Popular digital circuits. Directory. - Chelyabinsk: Metallurgy, Chelyabinsk Department, 1989.
3. Nechaev and. A simple, non-interference regulator. - Radio, 1991, No. 2, p. 67,68.
4. Horowitz P., Hill W. The art of circuitry. - M.: Mir, 1993.

Author: P.Redkin, Ulyanovsk

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