Timer for turning on and off electrical appliances circuit. Very handy countdown timer with LED digital display. Consider a circuit in hardware
The main component of the technical equipment of a modern house can be made do-it-yourself time relay. The essence of such a controller is to open and close electrical circuit according to the specified parameters in order to control the presence of voltage, for example, in the lighting network.
Purpose and design features
The most perfect such device is timer consisting with electronic elements. Its actuation moment is controlled by an electronic circuit according to the specified parameters, and the relay release time itself is calculated in seconds, minutes, hours or days.
According to the general classifier, turn-off or turn-on timers electrical circuit are divided into the following types:
- Mechanical device.
- Timer with an electronic load switch, for example, built on a thyristor.
- Device principle of operation, which is built on a pneumatic drive off and on.
Structurally, the operation timer can be made for installation on a flat plane, with a latch on a DIN rail and for mounting on the front panel of an automation and indication panel.
Also, according to the connection method, such a device can be front, rear, side and stuck through a special detachable element. Time programming can be done with a switch, potentiometer or buttons.
As already noted, of all the listed types of devices for tripping for a given time, the time relay circuit with electronic switching element.
This is because such a timer, operating on voltage, for example, 12v, has the following technical features:
- compact dimensions;
- minimum energy costs;
- lack of moving mechanisms, with the exception of off and on contacts;
- widely programmable task;
- long service life, independent of operation cycles.
The most interesting thing is that the timer is easy to do with your own hands at home. In practice, there are many types of circuits that give an exhaustive answer to the question of how to make a time relay.
The easiest 12V timer at home
The simplest solution is time relay 12 volt. Such a relay can be powered from a standard 12v power supply, of which there are a lot of sold in various stores.
The figure below shows a diagram of a device for turning on and off the lighting network, assembled on one counter of the integral type K561IE16.
Picture. A variant of the 12v relay circuit, when power is applied, it turns on the load for 3 minutes.
This circuit is interesting in that the generator of clock pulses is flashing LED VD1. Its flicker frequency is 1.4 Hz. If the LED of a particular brand cannot be found, then you can use a similar one.
Consider the initial state of operation, at the time of 12v power supply. At the initial moment of time, the capacitor C1 is fully charged through the resistor R2. Log.1 appears on the output under No. 11, making this element zero.
Transistor connected to the output integrated counter, opens and supplies a voltage of 12V to the relay coil, through the power contacts of which the load switching circuit closes.
The further principle of operation of the circuit operating at a voltage of 12V is pulse reading coming from the VD1 indicator with a frequency of 1.4 Hz to contact No. 10 of the DD1 counter. With each decrease in the level of the incoming signal, there is, so to speak, an increment in the value of the counting element.
On admission 256 pulse(this equals 183 seconds or 3 minutes) a log appears on pin #12. 1. Such a signal is a command to close the transistor VT1 and interrupt the load connection circuit through the relay contact system.
At the same time, log.1 from output under No. 12 is fed through the VD2 diode to the clock leg C of the DD1 element. This signal blocks the possibility of receiving clock pulses in the future, the timer will no longer work, until the 12V power supply is reset.
The initial parameters for the operation timer are set in different ways of connecting the transistor VT1 and the diode VD3 indicated in the diagram.
By slightly transforming such a device, you can make a circuit that has reverse principle of operation. The KT814A transistor should be changed to another type - KT815A, the emitter should be connected to the common wire, the collector to the first contact of the relay. The second contact of the relay should be connected to the 12V supply voltage.
Picture. A variant of the 12v relay circuit that turns on the load 3 minutes after power is applied.
Now after power up relay will be turned off, and the control pulse opening the relay in the form of a log.1 output 12 of the DD1 element will open the transistor and apply a voltage of 12V to the coil. After that, through the power contacts, the load will be connected to the electrical network.
This version of the timer, operating from a voltage of 12V, will keep the load in the off state for a period of 3 minutes, and then connect it.
When making the circuit, do not forget to place a 0.1 uF capacitor, labeled C3 on the circuit, with a voltage of 50V as close as possible to the supply pins of the microcircuit, otherwise the counter will often fail and holding time the relay will sometimes be smaller than it should be.
An interesting feature of the principle of operation of this scheme is the presence of additional features that are easy to implement if possible.
In particular, this is the programming of the exposure time. Using, for example, such a DIP switch as shown in the figure, you can connect one switch contacts to the outputs of the DD1 counter, and combine the second contacts together and connect to the connection point of the VD2 and R3 elements.
Thus, with the help of microswitches, you will be able to program holding time relay.
Connecting the connection point of the elements VD2 and R3 to different outputs DD1 will change the exposure time as follows:
| Counter foot number | Counter digit number | holding time |
|---|---|---|
| 7 | 3 | 6 sec |
| 5 | 4 | 11 sec |
| 4 | 5 | 23 sec |
| 6 | 6 | 45 sec |
| 13 | 7 | 1.5 min |
| 12 | 8 | 3 min |
| 14 | 9 | 6 min 6 sec |
| 15 | 10 | 12 min 11 sec |
| 1 | 11 | 24 min 22 sec |
| 2 | 12 | 48 min 46 sec |
| 3 | 13 | 1 hour 37 min 32 sec |
Completing the scheme with elements
To make such a timer operating at a voltage of 12v, you need to properly prepare the details of the circuit.
The elements of the schema are:
- diodes VD1 - VD2, marked 1N4128, KD103, KD102, KD522.
- A transistor that supplies 12v voltage to the relay - with the designation KT814A or KT814.
- Integrated counter, the basis of the principle of operation of the circuit, marked K561IE16 or CD4060.
- ARL5013URCB or L816BRSCB series LED fixture.
It is important to remember here that in the manufacture of a home-made device, it is necessary to use the elements indicated in the diagram and follow the safety rules.
A simple scheme for beginners
Beginning radio amateurs can try to make a timer, the principle of which is as simple as possible.
However, such simple device you can turn on the load for a specific time. True, the time for which the load is connected is always the same.
The algorithm of the circuit is as follows. When the button labeled SF1 is closed, the capacitor C1 is fully charged. When it is released, the specified element C1 begins to discharge through the resistance R1 and the base of the transistor, which has the designation in the circuit - VT1.
For the duration of the discharge current of the capacitor C1, while it is sufficient to maintain the transistor VT1 in the open state, relay K1 will be on and then off.
The specified ratings on the elements of the circuit provide the duration of the load for 5 minutes. The principle of operation of the device is such that the exposure time depends on the capacitance of the capacitor C1, the resistance R1, the current transfer coefficient of the transistor VT1 and the operating current of the relay K1.
If desired, you can change the response time by changing the capacitance C1.
Related videos
In this episode of the TV Soldering Iron channel, we will consider a simple circuit. It is a simple timer, or time relay. It is made on only one active component in the form of a reverse conduction bipolar transistor. A diagram is available for beginners and experienced radio amateurs for self-assembly. Radio parts are cheap in this Chinese store.
A few words about the element base. Diode D1 may not even be used. Replace with jumper. If you decide to use, then any low power diode, such as 1N4007, or any other rectifier diode. Capacitor C2 is selected if the device will be powered by a power supply. If from a battery, then there is no need for capacitor C2, since it is designed to filter the power. Resistors R2 and R1 with a power of 0.25 watts. However, it is possible and not so powerful 0.125 watts. Capacitor C1 in the circuit has a capacitance of 100 microfarads, but you need to choose it. It depends on the response time of the circuit. The voltage of this capacitor is 16-25 V, since the power supply is 12 V itself. Transistor T1 is any low-power bipolar transistor with reverse conductivity. You can even use KT315. The presented assembly uses a medium power transistor KT815A. You can also transistors high power, such as KT805, even KT803, KT819, and so on.
An electromagnetic relay winding is connected to the emitter circuit of the transistor to control powerful network loads. If the circuit is used to power low-voltage low-power loads, for example, LEDs, then the relay can be removed and the LED itself directly connected to the emitter circuit.
How does the circuit work?
When a power source is connected, 12 V, for example, power is supplied to the circuit, capacitor C1 is charged through the limiting resistor R2. And as soon as the charge on the capacitor has reached a certain level, power is supplied through the resistor R1 to the base of the transistor. As a result, the latter opens, and the plus through the transistor junction is fed to the winding of the electromagnetic relay. As a result, the latter closes, turning on or off the network load.
In the presented version, a conventional 220 V incandescent lamp was used as a network load. If you want to control network loads, then pay attention to the relay parameters. Firstly, the relay coil must be rated for 12 V. The contacts themselves must be quite powerful, depending, of course, on the connected load. That is, pay attention to the current allowed through the contacts.
The response time of the relay, that is, the charging time of the capacitor, is more dependent on the resistor R2. The higher its rating, the slower the capacitor will charge. And, of course, from the capacitance of the capacitor C itself. The higher its rating, the longer it will be charged, which means that more time required for charging and operation of the circuit.
Let's consider the circuit in iron.
The relay has a 12 V coil, this is indicated by the marking. Also admissible current through the contacts is 10 A at a voltage of 250 V, alternating. The transistor does not heat up at all in the circuit. But since the circuit has a rather large delay, with this layout of the used components, it was decided to change the resistance R2. In the circuit, 47 kΩ was replaced by 4.4 kΩ, and this resulted in a delay of 2-3 s.
Let's connect to a 12V power supply. This battery will be used, the exact voltage is somewhere around 10.8V. These are three lithium banks connected in series. Notice the LED. We have a blue LED connected through a 1 kΩ limiting resistor. As soon as the relay contacts are closed, power is supplied to the LED itself. Pay attention to the delay. Somewhere 2 s. Of course, the circuit can be in the on state for an infinitely long time.
This circuit can be used not only as a timer, but also as a Soft Start system. A system of pulsed powerful power supplies is used. Why is it advised to use soft start in powerful pulsed power supplies? Because when the circuit is connected to the network for a very short time, the circuit consumes an exorbitant current. This is because at the moment of switching on, the capacitors are charged with a large current. And as a result, other components of the circuit, for example, a diode bridge and so on, may not withstand such currents and fail. That is why this system is used.
How does a soft start system work in switching source circuits?
When connected to a 220 V network through a resistor that has some resistance and is current-quenching, that is, it limits the current, a powerful capacitor is charged through this resistor with a small current. And as soon as the capacitors are fully charged, the relay is already activated and the main power is supplied through the relay contacts to the circuit pulse source nutrition. Thus, for example, you can choose the time to charge the capacitor, set the response time here, and get a pretty good system for powerful switching power supplies. That's all. This is simple and affordable. Another simple diagram.
discussion
radmir tagirov
This is an example of how not to make a time relay. An inductive load must always be shunted by a diode. Otherwise, one fine time, your transistor will burn out. And why is the relay connected to the emitter?
Serghei
This is not a time relay, but a delay relay! Yes, and you put the diode in the wrong place!
Taras tsaryuk
and you don’t need to put a diode in parallel with a relay like yes!? if you don’t feel sorry for the transistor - when the transistor closes and the relay is de-energized, there is such garbage as a reverse current, at this moment the transistor will be full. Well, in general, whatever. If the details are not a pity.
An_
I assembled such a circuit, only without a diode and a conder at the input, and replaced the relay with an LED with a 300 kΩ resistor connected in series, trans kt 3102, when connected to a battery of approximately 12v, the LED slowly starts to glow and shines, shines, shines.! At a lower voltage at the power source, the picture is the same. I tried to change the conder and resistors - the difference in the speed of illumination of the LED. I thought it should light up and go out. Where is the mistake?
Zahar shoihit
this is really not a math lesson, but it seems to me that since the article is for beginners, it’s still worth explaining to people how to calculate the delay time.
Zahar shoihit
how did you get the 2 second delay?
After all, τ=rc 4. 4k*100µf=0. 44sec.
The 12 volt relay kicks in at about 9 volts.
That is 3/4 of the full charge of the capacitor.
3/4 of 5τ =(5*0.44)/4*3=1. 65sec
this is ideal, but in theory even less.
gimbal youtube
Good day. Is it possible to assemble a 4-pin relay with a 5-second delay based on this circuit? I would like to use something similar in overclocking a gantry crane.
daria novgorodova
guys, leave the person alone with your questions about the device of this relay. On my compressor, it has been turning off the starting conders for a year now. And I use the compressor quite often. And I also used it in the alarm. So far there have been no problems.
Andrey f
I'm not a magician, but I'm just learning. Comrades, electronics engineers, please explain if the base current of the transistor in this circuit appears more than once through r2, r1 and the coil. There is such an assumption, as the author says, that the transistor opens with a delay of 2 seconds, when a voltage appears on the upper plate as it charges, say 0.7 V, sufficient to open the transistor and the capacitance of the capacitor does not play a special role. Now, if there was a button with a flip contact between r2 and the connection node c1 and r1, then the size of the container would play its role for a long discharge. In short, who can explain.
Sako grig
the voltage to open the transistor 0. 7 v just appears after a few seconds, the time depends on the value of r2 and c1. With an increase in the capacitance of the capacitor, 0. 7 V will appear later, the same with an increase in r2, since the charging current of the capacitor will decrease. I*t=c*u
andrey f
Thanks for the clarification. I assembled the circuit in multisim, put the transistor 2n6488. The relay is connected to both the collector and the emitter. With a relay in the collector circuit, the circuit behaves approximately as you wrote on the basis of u \u003d 0.5v, the opening current is 0.01mA. And when the relay in the emitter circuit has a different picture, the voltage at the base u = 4b current is 0.01mA and the relay seems to work at 4v. I set the resistance and the capacitor different, the charge time changed in both cases.
Sako grig
In general, I recommended connecting the relay to the collector circuit, ground the emitter, put a 3-4 volt zener diode instead of r1 (to increase the delay time), it is advisable to take a transistor with a large current gain-h21e.
Sako grig
I don’t think that multisim can understand the intricacies of the operation of various modifications of the relay, for example, for some, although they are 12 volts, the response voltage is 8-9 volts, and the release voltage can be somewhere in the region of 3-4 volts.
Andrey f
it was interesting about 20 years ago when color TVs weighed 20 kg and in order to repair it, it was necessary to take it to the studio or call the master to the house, so I had to buy books myself and study this matter on my own, but my base is still small, since there wasn’t much to suggest to whom. Collect and see how the circuit works in multisim, why not. There are a lot of videos on the Internet, but there are very few such that thoroughly explain the operation of the circuit. Here, too, the author could show on the diagram the direction of currents, the voltage on the capacitor, based on the transistor. Then there would be no questions, why put the relay in the emitter circuit, and not the collector.
Stas stasovih
Could you tell me the simplest circuit of the delay switch off? Power supply 24v, delay after power off 60-120 seconds, I have all sorts of junk like pb from a computer, and small power supplies, is it possible to pull out components from there?
Sako grig
it depends on what you mean by shutting down. If the shutdown is to turn off the supply 24 volts, then only the battery in the circuit will save, if the shutdown must be done with the command button, there will be a different circuit.
Oleg Maltsev
it is working? But as? When the base reaches 0. 7v, the transistor will open and the supply voltage will appear on its emitter minus the voltage drop across transition to e, and in theory it should close until the voltage at the base appears more than the voltage at the emitter by 0. 7v. In theory, the relay must be connected to the collector and a blocking diode added. Not?
alex lamin
and it’s not easier for everyone to designate electrolytic capacitors in the same way with plus and minus what black and white are, you need to look for people separately to waste time.
alex lamin
hundreds of videos with the name of the time relay to find out the relay on or off you need to watch the videos to the end. And not easier to write in the title. People spend weeks searching. Not to mention the Iiot designation initially of any relay circuit. Where the coil is not indicated either on the diagram or on the relay. Instead of the usual signs, let's say zero and phase, some kind of drawing with abstract thinking.
Until now, some people use an hourglass to count small periods of time. Watching the movement of grains of sand in such watches is very exciting, but using them as a timer is not always convenient. Therefore, they are replaced by an electronic timer, the diagram of which is presented below.
Timer circuit
It is based on the widely used low-cost NE555 chip. The operation algorithm is as follows - when the S1 button is pressed briefly, a voltage equal to the circuit supply voltage appears at the OUT output and the LED1 LED lights up. After the specified time period has elapsed, the LED goes out, the output voltage becomes equal to zero. The timer operation time is set by the trimming resistor R1 and can vary from zero to 3-4 minutes. If there is a need to increase maximum time timer delay, then you can raise the capacitance of the capacitor C1 to 100 microfarads, then it will be about 10 minutes. As a transistor T1, you can use any bipolar transistor medium or low power n-p-n structures, for example, BC547, KT315, BD139. As button S1, any button for short circuit without fixation is used. The circuit is powered by a voltage of 9 - 12 volts, the current consumption without load does not exceed 10 mA.
Making a timer
The circuit is assembled on a 35x65 printed circuit board, a file for the Sprint Layout program is attached to the article. The tuning resistor can be installed directly on the board, or it can be output on the wires and a potentiometer can be used to adjust the operating time. To connect the power and load wires, the board has places for screw terminals. The board is made using the LUT method, a few photos of the process:
Download board:
(downloads: 251)
After soldering all the details, the board must be washed from the flux, the adjacent tracks should ring for a short circuit. The assembled timer does not need to be configured, it remains only to set the desired operating time and press the button. A relay can be connected to the OUT output, in which case the timer will be able to control a powerful load. When installing a relay in parallel with its winding, a diode should be placed to protect the transistor. The scope of such a timer is very wide and is limited only by the user's imagination. Happy assembly!
Quite simple, but sometimes admirable. If you recall the old washing machines, which were affectionately called “a bucket with a motor”, then the action of the time relay was very clear: they turned the knob a few divisions, something started ticking inside, and the motor started up.
As soon as the pen pointer reached the zero division of the scale, the wash ended. Later, machines appeared with two time relays - washing and spinning. In such machines, the time relays were made in the form of a metal cylinder, in which the clock mechanism was hidden, and outside there were only electrical contacts and a control knob.
Modern washing machines - automatic machines (with electronic control) also have a time relay, and it has become impossible to see it as a separate element or part on the control board. All time delays are obtained by software using the control microcontroller. If you look closely at the cycle of operation of an automatic washing machine, then the number of time delays simply cannot be counted. If all these time delays were performed in the form of the clock mechanism mentioned above, then there would simply not be enough space in the washing machine case.
From clockwork to electronics
How to get a time delay using MK
The speed of modern microcontrollers is very high, up to several tens of mips (millions of operations per second). It seems that not so long ago there was a struggle for 1 mips in personal computers. Now even older micros such as the 8051 family can easily do this 1 mips. Thus, it will take exactly one second to perform 1,000,000 operations.
Here, it would seem, is a ready-made solution on how to get a time delay. Just perform the same operation a million times. This is quite simple to do if this operation is looped in the program. But the whole trouble is that apart from this operation, for a whole second, MK will not be able to do anything else. So much for the achievement of engineering, so much for mips! And if you need an exposure of several tens of seconds or minutes?
Timer - a device for counting time
To prevent such embarrassment from happening, the processor did not just warm up, executing an unnecessary command that would not do anything useful, timers were built into the MK, as a rule, several of them. Without going into details, the timer is a binary counter that counts the pulses generated by a special circuit inside the MK.
For example, in the MK of the 8051 family, a counting pulse is generated when each command is executed, i.e. the timer simply counts the number of machine instructions executed. Meanwhile, the central processing unit (CPU) is quietly engaged in the execution of the main program.
Let's assume that the timer started counting (there is a command to start the counter for this) from zero. Each pulse increases the contents of the counter by one and, in the end, reaches the maximum value. After that, the contents of the counter are reset to zero. This moment is called "counter overflow". This is precisely the end of the time delay (recall a washing machine).
Let's assume that the timer is 8-digit, then it can be used to calculate the value within 0 ... 255, or the counter will overflow every 256 pulses. To make the shutter speed shorter, it is enough to start the count not from zero, but from a different value. To get it, it is enough to first load this value into the counter, and then start the counter (recall the washing machine again). This pre-loaded number is the angle of rotation of the time relay.
Such a timer with an operation frequency of 1 mips will allow you to get a shutter speed of a maximum of 255 microseconds, but you need several seconds or even minutes, what to do?
It turns out that everything is quite simple. Each timer overflow is an event that interrupts the main program. As a result, the CPU switches to the corresponding subroutine, which from such tiny excerpts can add up any one, even up to several hours or even days.
The interrupt service routine is usually short, no more than a few dozen commands, after which it returns to the main program again, which continues to be executed from the same place. Try to carry out such an excerpt by simply repeating the commands that were mentioned above! Although, in some cases it is necessary to do just that.
To do this, in the processor instruction systems, there is the NOP instruction, which just does nothing, only takes machine time. It can be used to reserve memory, and when creating time delays, only very short ones, on the order of microseconds.
Yes, the reader will say, how he suffered! From washing machines directly to microcontrollers. And what happened between these extreme points?
What are time relays
As already said, the main task of the time relay is to get the delay between the input signal and the output signal. This delay can be generated in several ways. The time relays were mechanical (already described at the beginning of the article), electromechanical (also based on a clockwork, only the spring is wound up by an electromagnet), as well as with various damping devices. An example of such a relay is the pneumatic timing relay shown in Figure 1.
The relay consists of an electromagnetic drive and a pneumatic attachment. The relay coil is produced for operating voltages 12 ... 660V alternating current(16 ratings in total) with a frequency of 50 ... 60 Hz. Depending on the version of the relay, the holding time can begin either when the electromagnetic actuator is activated or when it is released.
The time setting is carried out by a screw that regulates the cross section of the hole for the air outlet from the chamber. The described time relays are characterized by not very stable parameters, therefore, where possible, electronic time relays are always used. At present, such relays, both mechanical and pneumatic, can, perhaps, be found only in ancient equipment, which has not yet been replaced by modern equipment, and even in a museum.
Electronic time relays
Perhaps one of the most common was a series of relays VL - 60 ... 64 and some others, for example VL - 100 ... 140. All these time relays were built on a specialized chip KR512PS10. Appearance VL series relay is shown in Figure 2.
Figure 2. VL series time relay.
The scheme of the time relay VL - 64 is shown in Figure 3.
Figure 3
When the supply voltage is applied to the input through the rectifier bridge VD1 ... VD4, the voltage through the stabilizer on the KT315A transistor is supplied to the DD1 microcircuit, the internal generator of which begins to generate pulses. The pulse frequency is regulated by a variable resistor PPB-3B (it is he who is displayed on the front panel of the relay), connected in series with a 5100 pF time-setting capacitor, which has a tolerance of 1% and a very small TKE.
The received pulses are counted by a counter with a variable division ratio, which is set by switching the outputs of the microcircuit M01 ... M05. In the VL series relay, this switching was carried out at the factory. The maximum division ratio of the entire counter reaches 235,929,600. According to the documentation for the microcircuit, with a master oscillator frequency of 1 Hz, the shutter speed can reach over 9 months! According to the developers, this is quite enough for any application.
Conclusion 10 of the END chip - the end of the shutter speed, is connected to the input 3 - ST start - stop. As soon as a high-level voltage appears at the END output, the counting of pulses stops, and a high-level voltage appears on the 9th output of Q1, which opens the KT605 transistor and trips the relay connected to the KT605 collector.
Modern time relays
As a rule, they are made on MK. After all, it is easier to program a ready-made proprietary microcircuit, add a few buttons, a digital indicator, than to invent something new, and then also to fine-tune the time. Such a relay is shown in Figure 4.
Figure 4
Why make a time relay with your own hands?
And although there is such a huge number of time relays, for almost every taste, sometimes at home you have to do something of your own, often very simple. But such constructions most often justify themselves entirely. Here is some of them.
Since we have just examined the operation of the KR512PS10 microcircuit as part of the VL relay, then consideration of amateur circuits will have to begin with it. Figure 5 shows the timer circuit.
Figure 5. Timer on the KR524PS10 chip.
The microcircuit is powered by a parametric stabilizer R4, VD1 with a stabilization voltage of about 5 V. At the moment the power is turned on, the R1C1 circuit generates a reset pulse for the microcircuit. This starts the internal generator, the frequency of which is set by the R2C2 chain, and the internal counter of the microcircuit starts counting pulses.
The number of these pulses (counter division ratio) is set by switching the outputs of the M01 ... M05 microcircuit. With the position indicated on the diagram, this coefficient will be 78643200. This number of pulses is the full period of the signal at the END output (pin 10). Pin 10 is connected to pin 3 ST (start/stop).
As soon as a high level is set at the END output (half a period has been counted), the counter stops. At the same moment, a high level is also set at the output of Q1 (pin 9), which opens the transistor VT1. Through the open transistor, relay K1 is turned on, which controls the load with its contacts.
In order to start the time delay again, it is enough to briefly turn off and turn on the relay again. The timing diagram of the END and Q1 signals is shown in Figure 6.
Figure 6. Timing diagram of END and Q1 signals.
With the ratings of the timing circuit R2C2 indicated in the diagram, the generator frequency is about 1000 Hz. Therefore, the time delay with the specified connection of terminals M01 ... M05 will be about ten hours.
To fine-tune this shutter speed, do the following. Connect terminals M01…M05 to the position “Seconds_10”, as shown in the table in figure 7.
Figure 7 Timer Time Setting Table (click on picture to enlarge).
With this connection, by rotating the variable resistor R2, adjust the shutter speed for 10 seconds. by stopwatch. Then connect the terminals M01 ... M05, as shown in the diagram.
Another circuit on KR512PS10 is shown in Figure 8.
Figure 8 Time relay on a microcircuit KR512PS10
Another timer on the KR512PS10 chip.
To begin with, let's pay attention to the KR512PS10, more precisely, to the END signals, which are not shown at all, and the ST signal, which is simply connected to a common wire, which corresponds to a logic zero level.
With this inclusion, the counter will not stop, as shown in Figure 6. The END and Q1 signals will continue cyclically without stopping. In this case, the shape of these signals will be a classic meander. Thus, it turned out just a generator of rectangular pulses, the frequency of which can be controlled by a variable resistor R2, and the counter division ratio can be set according to the table shown in Figure 7.
Continuous pulses from the output of Q1 are fed to the counting input of the decimal counter - decoder DD2 K561IE8. The R4C5 chain resets the counter to zero when the power is turned on. As a result, a high level appears at the output of the decoder "0" (pin 3). Outputs 1…9 are low. With the arrival of the first counting pulse, the high level moves to output "1", the second pulse sets a high level at output "2", and so on, up to output "9". After that, the counter overflows and the counting cycle begins anew.
The received control signal through the SA1 switch can be applied to the audio signal generator on the elements DD3.1 ... 4, or to the relay amplifier VT2. The time delay depends on the position of the switch SA1. With the connections of terminals M01 ... M05 indicated on the diagram and the parameters of the timing chain R2C2, you can get time delays ranging from 30 seconds to 9 hours.
In some cases, it is necessary for the appliance to work in a periodic mode - after a certain time it turns on, works for a while and turns off again, that is, almost like a refrigerator, but the frequency does not depend on temperature, but on the set time intervals. Figure 1 shows a timer diagram in which the duration of the device and the duration of rest can be set separately in the range from 90 seconds to 3 hours, separately for each mode.
Time intervals are set smoothly by two variable resistors. The values of time intervals depend on the parameters of RC circuits with variable resistors in R - components. Therefore, this timer is suitable only in cases where very high accuracy in setting intervals is not required.
The circuit consists of two timer nodes on CD4060 microcircuits, switched using a trigger. One of these nodes manages the period of work, and the other - the period of rest. The CD4060 is a 14-bit binary counter with multivibrator elements. Therefore, the CD4060 is often used in simple timer circuits.
On the D1 chip, a timer is made that fulfills the period of operation (on state) of the device. At the moment of power-up (or after pressing the button S1), due to the charging of C2 through R8, the RS-flip-flop on D3 is set to a state with a logical unit at the output D3.3. The transistor key VT1-VT2 opens and turns on the device by means of relay K1.
At the same time counter D1 starts to work. And the counter D2 is held by one from the output D3.1 in the zero state.
After some time, depending on the frequency of the built-in multivibrator (C1-R1-R2), a logical unit appears at the senior output of D1 (pin 3). This unit switches the RS-flip-flop D3 to the opposite state. Key VT1-VT2 closes and turns off the device. A unit from the output of D3.2 resets the counter D1 and fixes it in this (zero) state. Zero output D3.1 allows counter D2 to work.
From this moment, the pause period begins. Now the counter D1 is blocked, and the counter D2 counts the pulses of its own multivibrator, the frequency of which, and hence the time to reach states 8192, depends on the resistance R6. After a specified time, one appears at pin 3 D2, and the circuit returns to its original state, that is, the appliance turns on and starts counting D1.
Thus, thanks to the trigger on D3, the counters work alternately - D1 counts the duration of the on state of the relay K1, then D2 counts the duration of the off state of K1, and so on.
Resistor R2 regulates the duration of the on state, and resistor R6 - the duration of the off state. Buttons S1 and S2 are non-latching, they serve for manual control of the timer state. By pressing S1, we transfer the circuit to the on-load state, and by pressing S2, to the off-state. This starts the countdown of the corresponding time interval. The HL1 LED signals the switching on of the relay K1.
The scheme in fig. 1, due to the parametric setting of the frequency of the multivibrators, it does not differ in high accuracy in working out time intervals. It is possible to achieve high accuracy and a significant expansion of the installation limits by applying quartz frequency stabilization of the clock multivibrator.
Fig.2
On fig. 2 shows just such a variant of the timer. Here, for each mode, intervals can be set in two ranges - from 1 second to 2047 seconds or from 1 minute to 2047 minutes, that is, practically, from 1 second to 34 hours. Moreover, in the first range, the setting is made in increments of one second, and in the second - in increments of one minute.
The only inconvenience is the installation method - with microswitches, converting the number of seconds (or minutes) into binary code. But this should not cause difficulties for a radio amateur. The accuracy of working out intervals is quartz, and the presence of a backup power source saves the timer in the event of a temporary power outage.
The principle of operation of the circuit is the same as in Figure 1, the same trigger with a key and a relay, but both counters operate from the same generator, and the time interval within the range is set by changing the counter division factor, and not the frequency of the multivibrator.
A 2Hz frequency generator is made on the D1 chip. This is a CD4060 multivibrator counter, the multivibrator of which is connected according to a typical circuit with a quartz resonator. Clock resonator, at 32768 Hz. The maximum division ratio of the CD4060 counter is 16384 (2x8192). Therefore, when dividing 32768 by 16384, the output is 2 Hz.
Switches S1 and S2 serve to select the range (seconds / minutes). In the diagram, they are in the second position. In this case, the inputs D4 and D5 (CD4040) receive pulses with a frequency of 2 Hz. The first triggers of counters D4 and D5 serve to divide the given frequency by 2 to be 1 Hz, so outputs with weights of "1" of these counters are not used.
The division ratios D4 and D5 are set by a circuit of diodes, microswitches and resistors. The interval is set by closing the switches according to the binary code.
For example, you need to set the duration of work to 40 seconds and pause to 30 seconds. Of the switches S3-S13, we close those whose coefficients add up to the number 40, that is, 32+8=40, which means we close S8 and S6. The rest are open. And from among the switches S14-S24 we close those whose coefficients give a total of 30, that is, 16+8+4+2=30, which means we close S15, S16, S17, S18, and leave the rest of the switches open.
After 40 seconds have passed, a logic unit voltage will appear on C5, which will switch the trigger to D3. In this case, the load will turn off, the counter D4 will be blocked by a unit from the output D3.2, and the counter D5 will be started by a logical zero from the output D3.1. The pause interval will begin. After 30 seconds, a logical unit will appear on C6 and the circuit will return to its original position.
The purpose of the buttons S25 and S26 is the same as the buttons S1 and S2 in the diagram in Figure 1.
In order to receive the following pulses with a period of 30 seconds between the output D1 and the inputs D4 and D5, a divider by 60 assembled on another binary counter CD4040 (D2) is switched on through the switches S1 and S2. Diodes VD3-VD6 and resistor R3 limit its count to 60. Then, with the onset of the 60th input pulse, it is reset to zero. As a result, its output 2 has pulses with a period of 30 seconds. Then, they divide the first triggers D4 and D5 into two more, and further, we set the time not in seconds, but in minutes.
For example, you want the fan to turn on every 2 hours and run for 85 seconds. To do this, set S1 to the second position (as in the diagram), turn on S9, S7, S5, S3 (64+16+ 4+1=85). Next, switch S2 to minutes (opposite to the diagram), convert hours to minutes - 2 hours = 120 minutes, and turn on S20, S19, S18, S17 (64+32+16+8=120). Leave the rest of the switches open.
Backup power is provided by Krona G1. As long as there is a voltage of 12V coming from the mains source, the VD2 diode is closed and Krona's energy is not consumed. When the mains source is turned off, the diode VD2 opens, but VD29 closes. Therefore, when there is a power outage, only microcircuits are powered from the Krona, and the output key and relays do not work.
The timers use the SCB-1-M-1240 electromagnetic relay. Such relays are used in electrical equipment cars, in car alarms. Despite the automotive specialization, this relay can switch a load powered by 220V AC, with a power of up to 2000 W. Of course, you can use another relay, corresponding to the power, with a 12V winding.
Diodes KD522 can be replaced by any analogues, for example, 1N4148. CD4060B microcircuits are interchangeable with any other type xx4060, for example, pPD4060, HCC4060, M4060, NJM4060, etc. There are no domestic analogues. Microcircuits CD4040 are interchangeable with others like xx4040 or domestic K561IE20, K1561IE20. Capacitors C1 and C4 (Fig. 1) must be non-polar.
