How to assemble a time relay from a clock. Electronic on-off timer. Timer for intermittent mode - Meander - entertaining electronics

In everyday life, it is often necessary to turn off the lights after a certain time. There is a need for storage rooms and simple outbuildings. In turn, and in other cases when it is necessary to limit the operation of any electronic device in time, a simple digital timer will be used in place, which allows you to turn on or off the load after a certain period.

Simple digital light on/off timer, which you can assemble with your own hands, is built on only one integrated counter K561IE16. As you know, to operate any counter you need an external clock generator. In our case, its role is played by a simple flashing LED.

Description of the operation circuit of a simple digital timer

As soon as the timer power is turned on, C1 is charged through resistance R2, as a result of which logic 1 briefly appears at pin 11, turning all counter outputs to zero. The transistor connected to the meter output will open and the relay will operate, connecting the load with its contacts.

From a flashing LED with a frequency of about 1.4 Hz, pulses are sent to the clock input (pin 10) of the counter DD1. With each fall of the input pulse, the counter increments. After 256 pulses have passed (in time this will take approximately 256 / 1.4 Hz = 183 seconds or ~ 3 minutes), logic 1 appears at pin 12. In this regard, the transistor will close, de-energizing the load. Plus, logic 1 from output 12 is supplied to the clock input DD1 through the diode VD1, thereby stopping the timer.

The frequency of operation of the timer can be selected by connecting the connection point of resistor R3 and diode VD1 to various outputs of DD1. By slightly adjusting this circuit, it is possible to build a timer that performs the opposite function. The change affects transistor VT1. It must be replaced with a transistor of a different structure.

Now, when log.1 appears at the output of the counter, the transistor will open and turn on the load. Instead of an electric relay in this version, it is possible to turn on a simple sound emitter with an internal generator, for example, HCM1612X. The electric emitter must be connected with correct polarity.

Light On/Off Timer Details

Diodes VD1-VD2 series KD103, KD522, KD103, KD521, KD102. KT814A transistors can be replaced with KT973 or KT814. arbitrary from the KT604, KT815 series. In addition to the K561IE16 counter, it is possible to use its foreign analog CD4020B. You can also use the CD4060 chip, which already has a clock generator, so the LED and resistance R1 can be removed. LED – flashing type ARL5013URCB, L816BRSCВ, L56DGD,

The timer is quite economical in terms of energy consumption. The current consumed by the timer, not including the relay current, is about 11 mA.

To ensure precise intervals of time when performing various actions using electrical equipment, time relays are used.

They are used everywhere in everyday life: electronic alarm clock, changing operating modes of a washing machine, microwave oven, exhaust fans in the toilet and bathroom, automatic watering of plants, etc.

Advantages of timers

Of all the varieties, electronic devices are the most common. Their advantages:

• small sizes;
• exceptionally low energy consumption;
• no moving parts except for the electromagnetic relay mechanism;
• wide range of time exposures;
• independence of service life from the number of operating cycles.

Transistor time relay

With basic electrician skills, you can make an electronic time relay with your own hands. It is mounted in a plastic case, which houses the power supply, relay, board and control elements.

The simplest timer

The time relay (diagram below) connects the load to the power supply for a period of 1-60 seconds. The transistor switch controls the electronic relay K1, which connects the consumer to the network with contact K1.1.

In the initial state, switch S1 closes capacitor C1 to resistance R2, which keeps it discharged. Electromagnetic switch K1 does not work in this case, since the transistor is locked. When the capacitor is connected to the power supply (upper position of contact S1), its charging begins. A current flows through the base, which opens the transistor and K1 turns on, closing the load circuit. The supply voltage to the time relay is 12 volts.

As the capacitor charges, the base current gradually decreases. Accordingly, the magnitude of the collector current drops until K1, by turning off, opens the load circuit with contact K1.1.

To reconnect the load to the network for a specified period of operation, the circuit must be restarted again. To do this, the switch is set to the lower "off" position, which leads to the discharge of the capacitor. The device is then turned on again by S1 for a specified period of time. The delay is adjusted by installing resistor R1, and can also be changed if the capacitor is replaced with another one.

The principle of operation of a relay using a capacitor is based on its charging for a time depending on the product of the capacitance and the resistance of the electrical circuit.

Timer circuit with two transistors

It is not difficult to assemble a time relay with your own hands using two transistors. It starts working if you apply power to capacitor C1, after which it will begin charging. In this case, the base current opens transistor VT1. Following it, VT2 will open, and the electromagnet closes the contact, supplying power to the LED. Its glow will indicate that the time relay has activated. The circuit provides load switching R4.

As the capacitor charges, the emitter current gradually decreases until the transistor turns off. As a result, the relay will turn off and the LED will stop working.

The device restarts if you press the SB1 button and then release it. In this case, the capacitor will discharge and the process will repeat.

Operation begins when the 12V time relay is energized. For this purpose, autonomous sources can be used. When powered from the network, a power supply consisting of a transformer, rectifier and stabilizer is connected to the timer.

Time relay 220v

Most electronic circuits operate at low voltage with galvanic isolation from the network, but can still switch significant loads.

The time delay can be made from a 220V time relay. Everyone knows electromechanical devices with a delay in turning off old washing machines. It was enough to turn the timer knob, and the device turned on the engine for a specified time.

Electromechanical timers have been replaced by electronic devices, which are also used for temporary lighting in the toilet, on the landing, in a photo enlarger, etc. In this case, contactless switches on thyristors are often used, where the circuit operates from a 220 V network.

Power is supplied through a diode bridge with a permissible current of 1 A or more. When the contact of switch S1 closes, in the process of charging capacitor C1, thyristor VS1 opens and lamp L1 lights up. It serves as a load. Once fully charged, the thyristor will close. This will be visible when the lamp turns off.

The lamp burns for a few seconds. It can be changed by installing capacitor C1 with a different value or connecting a 1 kOhm variable resistor to diode D5.

Time relay on microcircuits

Transistor timer circuits have many disadvantages: the difficulty of determining the delay time, the need to discharge the capacitor before the next start, and short response intervals. The NE555 chip, called the “integrated timer,” has long gained popularity. It is used in industry, but you can see many schemes for making time relays with your own hands.

The time delay is set by resistances R2, R4 and capacitor C1. The load connection contact K1.1 closes when the SB1 button is pressed, and then it opens independently after a delay, the duration of which is determined from the formula: t and = 1.1R2∙R4∙C1.

When you press the button again, the process repeats.

Many household appliances use microcircuits with time relays. Instructions for use are a necessary attribute of proper operation. It is also compiled for do-it-yourself timers. Their reliability and durability depend on this.

The circuit operates from a simple 12 V power supply consisting of a transformer, diode bridge and capacitor. The current consumption is 50 mA, and the relay switches a load of up to 10 A. The adjustable delay can be made from 3 to 150 s.

Conclusion

For domestic purposes, you can easily assemble a time relay with your own hands. Electronic circuits work well on transistors and microcircuits. You can set a contactless timer on thyristors. It can be turned on without galvanic isolation from the existing network.

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The simplest cyclic timer. The simplest device for cyclically switching on and off the load.

My development Krylov P.V.

Every winter the same problem arises. In severe frosts, the water supply from the well to the house freezes. This happens because the entrance to the house is made above the foundation. Although it is insulated with mineral wool, it freezes in severe frosts. This always happens at night when we are not using water. Accordingly, the pump does not turn on, the water is not pumped and freezes. A partial solution was found. At night they began to leave the cold water tap slightly open. But this doesn't always help. The valve axleboxes have a slight play and shut off the water at low pressure. This is how the idea of ​​making a cyclic timer came about. A device that would turn on the pump for a few seconds and then hold it for several tens of minutes.

This device turns on the pump for 6 seconds after 20 minutes of exposure, then the cycle is repeated. Such a device can be used in ventilation systems, drip irrigation and other continuous-cyclic systems. Waiting and operating times can be varied within wide limits.

Analysis of what was on the Internet raised many questions.
I really liked the device in the article

But unfortunately, it is impossible to buy the K561IE5 microcircuit. Another article gave an overly complex diagram.

I chose the Kalashnikov principle. Extraordinary simplicity.

Note It is advisable to remove container C1. When checking, it turned out that this capacity does not have time to discharge when reset through the “AND” circuit.

The circuit is assembled on just one chip - a 14-bit counter CD4020, Russian analogue K561IE16.

The blinking LED is a generator with a frequency of approximately 3 pulses per 2 seconds.

At the input for supplying clock pulses C (pin 10) of the DD1 microcircuit there are pulses with a frequency of approximately 1.4-1.5 Hz. When the LED flashes at input C, the level is high, and when it goes out, this level changes to low. As the pulses fall at input C, counting begins. High levels appear at the counter outputs in accordance with the binary representation of the number of pulses arriving at the input. For example, if 16 pulses arrived at input C, then at output Q4 the pin of microcircuit No. 5 will appear 1 or a high level, all other pins will have “0”

After supplying power to the device, capacitor C1 begins to charge through resistor R2, a high level is set at the R input of the DD1 microcircuit, due to which a low level will be present at all its outputs.

The reset circuit does not work entirely correctly, because sometimes after switching on the outputs 1.

My introductions.

I introduced a logical element “AND” into the circuit.

These are elements R5, D2, D3. If there is a 1 on pins Q3, Q11, then the “AND” circuit will work and the CD4020 chip will be reset. A high level at output Q11 will appear if 2048 pulses arrive at input C, which corresponds to approximately 21 minutes. At this moment, transistor VT1 will open and relay K1 will operate. The pump will turn on. After another eight pulses arrive at input C, which corresponds to 6 seconds, a high level will appear at output Q3, pin No. 7, and a reset will be triggered through the “AND” circuit. The pump will turn off. Then the counting cycle will repeat.

Details.

D5 any flashing LED.
We will replace the flashing LED (except for the one indicated in the diagram) with L-816BRSC-B, L-56DGD, ARL-5013URC-B or similar. But in principle, any flashing LED will do.

Diodes D1, D2, D3, D6 - any of the KD521, KD522, KD102, KD103 or 1N4148 series. VD 4 any LED. It is used to indicate the operation of the meter. Changes its state every 8 pulses arriving at input C.

Relay K1 - any with an operating voltage of 10... 12 V.

Modification of the scheme.

If you switch diode D3 from pin 1 to pin 2 of the microcircuit, i.e. from Q11 to Q12, the shutter speed (pause) will double from 20 minutes to 40 minutes. If you switch from Q3 physical. pin 7 to Q4 physical. pin 5, then the operating time will double from 5-6 seconds to 10-12 seconds.

The scheme has been verified. Assembled on a breadboard. Video of the work below.

To ensure precise intervals of time when performing various actions using electrical equipment, time relays are used.

They are used everywhere in everyday life: electronic alarm clock, changing operating modes of a washing machine, microwave oven, exhaust fans in the toilet and bathroom, automatic watering of plants, etc.

Advantages of timers

Of all the varieties, electronic devices are the most common. Their advantages:

• small sizes;
• exceptionally low energy consumption;
• no moving parts except for the electromagnetic relay mechanism;
• wide range of time exposures;
• independence of service life from the number of operating cycles.

Transistor time relay

With basic electrician skills, you can make an electronic time relay with your own hands. It is mounted in a plastic case, which houses the power supply, relay, board and control elements.

The simplest timer

The time relay (diagram below) connects the load to the power supply for a period of 1-60 seconds. The transistor switch controls the electronic relay K1, which connects the consumer to the network with contact K1.1.

In the initial state, switch S1 closes capacitor C1 to resistance R2, which keeps it discharged. Electromagnetic switch K1 does not work in this case, since the transistor is locked. When the capacitor is connected to the power supply (upper position of contact S1), its charging begins. A current flows through the base, which opens the transistor and K1 turns on, closing the load circuit. The supply voltage to the time relay is 12 volts.

As the capacitor charges, the base current gradually decreases. Accordingly, the magnitude of the collector current drops until K1, by turning off, opens the load circuit with contact K1.1.

To reconnect the load to the network for a specified period of operation, the circuit must be restarted again. To do this, the switch is set to the lower "off" position, which leads to the discharge of the capacitor. The device is then turned on again by S1 for a specified period of time. The delay is adjusted by installing resistor R1, and can also be changed if the capacitor is replaced with another one.

The principle of operation of a relay using a capacitor is based on its charging for a time depending on the product of the capacitance and the resistance of the electrical circuit.

Timer circuit with two transistors

It is not difficult to assemble a time relay with your own hands using two transistors. It starts working if you apply power to capacitor C1, after which it will begin charging. In this case, the base current opens transistor VT1. Following it, VT2 will open, and the electromagnet closes the contact, supplying power to the LED. Its glow will indicate that the time relay has activated. The circuit provides load switching R4.

As the capacitor charges, the emitter current gradually decreases until the transistor turns off. As a result, the relay will turn off and the LED will stop working.

The device restarts if you press the SB1 button and then release it. In this case, the capacitor will discharge and the process will repeat.

Operation begins when the 12V time relay is energized. For this purpose, autonomous sources can be used. When powered from the network, a power supply consisting of a transformer, rectifier and stabilizer is connected to the timer.

Time relay 220v

Most electronic circuits operate at low voltage with galvanic isolation from the network, but can still switch significant loads.

The time delay can be made from a 220V time relay. Everyone knows electromechanical devices with a delay in turning off old washing machines. It was enough to turn the timer knob, and the device turned on the engine for a specified time.

Electromechanical timers have been replaced by electronic devices, which are also used for temporary lighting in the toilet, on the landing, in a photo enlarger, etc. In this case, contactless switches on thyristors are often used, where the circuit operates from a 220 V network.

Power is supplied through a diode bridge with a permissible current of 1 A or more. When the contact of switch S1 closes, in the process of charging capacitor C1, thyristor VS1 opens and lamp L1 lights up. It serves as a load. Once fully charged, the thyristor will close. This will be visible when the lamp turns off.

The lamp burns for a few seconds. It can be changed by installing capacitor C1 with a different value or connecting a 1 kOhm variable resistor to diode D5.

Time relay on microcircuits

Transistor timer circuits have many disadvantages: the difficulty of determining the delay time, the need to discharge the capacitor before the next start, and short response intervals. The NE555 chip, called the “integrated timer,” has long gained popularity. It is used in industry, but you can see many schemes for making time relays with your own hands.

The time delay is set by resistances R2, R4 and capacitor C1. The load connection contact K1.1 closes when the SB1 button is pressed, and then it opens independently after a delay, the duration of which is determined from the formula: t and = 1.1R2∙R4∙C1.

When you press the button again, the process repeats.

Many household appliances use microcircuits with time relays. Instructions for use are a necessary attribute of proper operation. It is also compiled for do-it-yourself timers. Their reliability and durability depend on this.

The circuit operates from a simple 12 V power supply consisting of a transformer, diode bridge and capacitor. The current consumption is 50 mA, and the relay switches a load of up to 10 A. The adjustable delay can be made from 3 to 150 s.

Conclusion

For domestic purposes, you can easily assemble a time relay with your own hands. Electronic circuits work well on transistors and microcircuits. You can set a contactless timer on thyristors. It can be turned on without galvanic isolation from the existing network.

Timer circuit on the K561IE16 counter

The design is made on only one chip K561IE16. Since, for its correct operation, an external clock generator is needed, in our case we will replace it with a simple blinking LED.

As soon as we apply power to the timer circuit, the capacitance C1 will start charging through the resistor R2 therefore, a logical one will briefly appear at pin 11, resetting the counter. The transistor connected to the meter output will open and turn on the relay, which will connect the load through its contacts.

With a flashing LED with a frequency 1.4 Hz pulses are sent to the clock input of the counter. With each pulse drop the counter counts. Through 256 pulses or about three minutes, a logical one level will appear at pin 12 of the counter, and the transistor will close, turning off the relay and the load switched through its contacts. In addition, this logical unit passes to the DD clock input, stopping the timer. The operating time of the timer can be selected by connecting point “A” of the circuit to various outputs of the counter.

The timer circuit is made on a microcircuit KR512PS10, which has in its internal composition a binary counter-divider and a multivibrator. Like a conventional counter, this microcircuit has a division coefficient from 2048 to 235929600. The selection of the required coefficient is set by applying logical signals to the control inputs M1, M2, M3, M4, M5.

For our timer circuit, the division factor is 1310720. The timer has six fixed time intervals: half an hour, an hour and a half, three hours, six hours, twelve hours and a day of an hour. The operating frequency of the built-in multivibrator is determined by the resistor values R2 and capacitor C2. When switch SA2 is switched, the frequency of the multivibrator changes, and passing through the counter-divider and the time interval.

The timer circuit starts immediately after turning on the power, or you can press the SA1 toggle switch to reset the timer. In the initial state, the ninth output will have a logical one level and the tenth inverse output, respectively, a zero. As a result of this, the transistor VT1 connects the LED part of the optothyristors DA1, DA2. The thyristor part has an anti-parallel connection, this allows you to regulate the alternating voltage.

Upon completion of the time countdown, the ninth output will set to zero and turn off the load. And at output 10 a unit will appear, which will stop the counter.

The timer circuit is launched by pressing one of three buttons with a fixed time interval, and it begins to count down. In parallel with pressing the button, the LED corresponding to the button lights up.

When the time interval expires, the timer emits a sound signal. A subsequent press will turn off the circuit. Time intervals are changed by the ratings of radio components R2, R3, R4 and C1.

Timer circuit, which provides a turn-off delay, is shown in the first figure. Here, a transistor with a p-type channel (2) is connected to the load power circuit, and a transistor with a n-type channel (1) controls it.

The timer circuit works as follows. In the initial state, capacitor C1 is discharged, both transistors are closed and the load is de-energized. When you briefly press the Start button, the gate of the second transistor is connected to the common wire, the voltage between its source and gate becomes equal to the supply voltage, it instantly opens, connecting the load. The voltage surge that appears on it through capacitor C1 is supplied to the gate of the first transistor, which also opens, so the gate of the second transistor will remain connected to the common wire even after the button is released.

As capacitor C1 is charged through resistor R1, the voltage across it increases, and at the gate of the first transistor (relative to the common wire) decreases. After some time, depending mainly on the capacitance of capacitor C1 and the resistance of resistor R1, it decreases so much that the transistor begins to close and the voltage at its drain increases. This leads to a decrease in the voltage at the gate of the second transistor, so the latter also begins to close and the voltage across the load decreases. As a result, the voltage at the gate of the first transistor begins to decrease even faster.

The process proceeds like an avalanche, and soon both transistors close, de-energizing the load, capacitor C1 quickly discharges through diode VD1 and the load. The device is ready to start again. Since the field-effect transistors of the assembly begin to open at a gate-source voltage of 2.5...3 V, and the maximum permissible voltage between the gate and source is 20 V, the device can operate with a supply voltage from 5 to 20 V (nominal voltage of capacitor C1 should be a few volts more than the supply). The shutdown delay time depends not only on the parameters of elements C1, R1, but also on the supply voltage. For example, increasing the supply voltage from 5 to 10 V leads to its increase by approximately 1.5 times (with the nominal values ​​of the elements indicated in the diagram, it was 50 and 75 s, respectively).

If, with the transistors closed, the voltage across resistor R2 is more than 0.5 V, then its resistance must be reduced. A device that provides a switch-on delay can be assembled according to the circuit shown in Fig. 2. Here the transistors of the assembly are connected in approximately the same way, but the voltage to the gate of the first transistor and capacitor C1 is supplied through resistor R2. In the initial state (after connecting the power source or after pressing the SB1 button), capacitor C1 is discharged and both transistors are closed, so the load is de-energized. As R1 and R2 charge, the voltage across the capacitor rises, and when it reaches approximately 2.5 V, the first transistor begins to turn on, the voltage drop across R3 increases, and the second transistor also begins to turn on. When the load voltage increases so much that diode VD1 opens, the voltage across resistor R1 increases. This leads to the fact that the first transistor, and then the second one, opens faster and the device abruptly switches to the open state, closing the load power circuit

The timer circuit is a restart, for this you need to press the button and hold it in this state for 2...3 s (this time is enough to completely discharge capacitor C1). Timers are mounted on printed circuit boards made of fiberglass foil on one side, the drawings of which are shown in Fig. 3 and 4. The boards are designed for the use of diodes of the KD521, KD522 series and surface mounting parts (resistors R1-12, size 1206 and tantalum oxide capacitor). Setting up devices comes down mainly to selecting resistors to obtain the required time delay.

The described devices are designed to be included in the positive power supply wire of the load. However, since the IRF7309 assembly contains transistors with both channel types, the timers can easily be adapted to be included in the negative wire. To do this, the transistors should be swapped and the diode and capacitor switched on in reverse polarity (of course, this will require corresponding changes in the printed circuit board drawings). It should be taken into account that if the connecting wires are long or there are no capacitors in the load, interference on these wires and uncontrolled activation of the timer is possible. To increase noise immunity, a capacitor with a capacity of several microfarads with a rated voltage not less than the supply voltage must be connected to its output.

Five minute timer circuit

If the time interval is more than 5 minutes, the device can be restarted and continue counting again.

After a short circuit of SВ1, capacitance C1, connected to the collector circuit of transistor VT1, begins to charge. The voltage from C1 is supplied to an amplifier with a high input resistance on transistors VT2-VT4. Its load is an LED indicator that turns on alternately every minute.

The design allows you to choose one of five possible time intervals: 1.5, 3, 6, 12 and 24 hours. The load is connected to the AC network at the moment the countdown begins and is disconnected at the end of the countdown. Time intervals are set using a frequency divider of square wave signals generated by an RC multivibrator.

The master oscillator is made on the logical components DD1.1 and DD1.2 of the microcircuit K561LE5. The generation frequency is formed by an RC circuit on R1,C1. The accuracy of the stroke is adjusted over the shortest time interval, using the selection of resistance R1 (temporarily, when adjusting, it is advisable to replace it with a variable resistance). To create the necessary time ranges, pulses from the multivibrator output go to two counters DD2 and DD3, as a result of which the frequency is divided.

These two counters - K561IE16 are connected in series, but for simultaneous reset, the zeroing pins are connected together. Reset occurs using switch SA1. Another toggle switch SA2 selects the required time range.

When a logical one appears at the output of DD3, it goes to pin 6 of DD1.2, as a result of which the generation of pulses by the multivibrator ends. At the same time, the logical one signal goes to the input of the inverter DD1.3 to the output of which VT1 is connected. When a logical zero appears at the output of DD1.3, the transistor closes and turns off the LEDs of the optocouplers U1 and U2, and this turns off the triac VS1 and the load connected to it.

When the counters are reset, their outputs are set to zero, including the output to which switch SA2 is installed. A zero is also supplied at the input of DD1.3 and, accordingly, a unit at its output, which connects the load to the network. Also in parallel, the zero level will be set at input 6 of DD1.2, which will trigger the multivibrator and the timer will begin counting. The timer is powered using a transformerless circuit consisting of components C2, VD1, VD2 and C3.

When toggle switch SW1 is closed, capacitor C1 begins to slowly charge through resistance R1, and when the voltage level on it is 2/3 of the supply voltage, trigger IC1 will respond to this. In this case, the voltage at the third terminal will drop to zero, and the circuit with the light bulb will open.

With a resistance of resistor R1 of 10M (0.25 W) and capacitance C1 of 47 µF x 25 V, the operating time of the device is about 9 and a half minutes, if desired, it can be changed by adjusting the values ​​of R1 and C1. The dotted line in the figure indicates the inclusion of an additional switch, with which you can turn on the circuit with the light bulb even when the toggle switch is closed. The design's quiescent current is only 150 μA. Transistor BD681 - compound (Darlington) medium power. Can be replaced with BD675A/677A/679A.

This is a timer circuit on a PIC16F628A microcontroller, borrowed from a good Portuguese site on radio electronics. The microcontroller is clocked from an internal oscillator, which can be considered quite accurate for this moment, since pins 15 and 16 remain free, you can use an external quartz resonator for even greater accuracy in operation.