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Do-it-yourself weekly programmable timer. How to make a timer from an electronic clock with your own hands

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 turnkey solution how to get 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 warm up just like that, executing unnecessary command, which will 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 subroutine is usually short, no more than a few dozen commands, after which the return to the main program occurs 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 similar designs most often justify themselves completely. Here are 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 the exit END is set high level(half a period 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.

And turn off again. Just like a refrigerator, only the frequency of the refrigerator depends on the temperature, and we need to set the necessary time intervals ourselves.

Let's consider an electronic timer circuit in which the cycling of work and "rest" can be set separately. The time is set by variable resistors, in the range from 90 seconds to 3 hours, separately, for each mode. The values ​​of the set intervals completely depend on the parameters of the RC circuits, with variable resistors in the "R" components. In this regard, this electronic timer does not have very high accuracy.

The circuit consists of a timer node on a K561IE16 binary counter (analogue 4020), which differs from the "typical" one in that it has two adjustable multivibrators. By setting the frequency of one, set the duration of the on state, and by setting the frequency of the other, the duration of the off state. Multivibrators are switched by a transistor-diode circuit depending on the logic level at the counter's high output. The same counter output is used to control the load.

In the initial state (after the power is turned on by the switch SB1), the counter DD2 is set to zero by a jump in the charging current of the capacitor C2. Its output (pin 3) will be a logical zero. Transistor VT2 opens, transistor VT3 also opens and relay K1 closes its contacts, the output of the circuit is connected to a break in the power circuit of the electrical appliance that needs to be controlled. That is, practically, in parallel with the switch of this electrical appliance.

At the same time, zero from pin 3 of DD2 passes to pin 9 of DD1.4 and to the base of VT1. At the same time, VT1 is closed, there is a high voltage level on its collector, which comes to pin 6 of DD1.2. From here it turns out that the multivibrator assembled on the elements DD1.3-DD1.4 works, the pulses from its output pass through the diode VD1 to the counting input DD2. And the multivibrator on the elements DD1.1-DD1.2 does not work, its output is zero. But this does not affect the passage of pulses to the counter from the second multivibrator, since the VD2 diode turns out to be closed and does not affect the input of the counter.

Thus, the period of the on state of the electrical appliance begins. This will continue until the counter DD2 reaches the 8192nd pulse. That is, until a unit appears at its output 3. How long it will take depends on the resistance R7.

When a unit appears at pin 3 DD2, the interval of the on state of the appliance ends, and a pause begins. Transistors VT2-VT3 close and relay K1 turns off the appliance. And the transistor VT1 opens. At pin 9 DD1.4 passes one from the output of DD2, so the multivibrator DD1.3-DD1.4 turns off. On the collector VT1, the voltage drops to zero. This corresponds to the voltage at pin 6 DD1.2. Therefore, the multivibrator DD1.1-DD1.2 turns on. The pulses from its output through the diode VD2 are fed to the input "C" of the counter DD2. From this moment, the countdown of the pause interval begins. LED HL1 indicates the on state of the relay K1.

Any network adapter with an output nominal voltage of 9-15V and a current of at least 150 mA is suitable as a power source.

Using the SC1240 relay, it is possible to switch the load with a mains alternating voltage of 220V with a power of not more than 2 kW. If this is not available, you can also use a domestic relay, but you should give preference to those relays that are in a plastic case, since a similar relay in a metal case will not be able to safely operate on an alternating voltage of 220V. In addition, it is desirable to use specialized relays, the contacts of which and the design are primarily designed for switching mains alternating voltage.

Instead of a relay, you can use some kind of optothyristor or triac circuit. In this case, the transistor VT3 and, accordingly, the relay K1 are excluded from the circuit. And the optocoupler LED is connected instead of the resistor R13. The resistance R10 in this case must be selected according to what current should flow through the optocoupler LED.

The advantage of the relay is that it is, in fact, an ordinary mechanical switch, that is, the device is linear like a piece of wire, and does not introduce any distortions and additions (like surges at each half-cycle) to the sinusoid of the AC voltage from the mains. Therefore, it is still better to power electrical appliances with electronic components through a relay. And the disadvantage of the relay is obvious - mechanical contacts, sparking, burning, in general, mechanics, which in itself is not as reliable as a thyristor or triac. Therefore, if you need to control a powerful heating element, or some other electrical appliance without built-in electronics, then it is better to use an optosimistor.


Timer circuit on the counter K561IE16

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

As soon as we apply voltage to the timer circuit, the capacitance C1 will start charging through the resistor R2 therefore, a logical unit will briefly appear on 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 flashing LED with frequency 1.4 Hz pulses are sent to the clock input of the counter. With each pulse transition, a counter is counted. Through 256 impulses or about three minutes, a logical unit 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 ratio from 2048 to 235929600. The choice of the required ratio is set by applying logic 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 frequency of operation of the built-in multivibrator is determined by the resistor values R2 and capacitor C2. When switching switch SA2, the frequency of the multivibrator changes, and passing through the counter-divider and the time interval.

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

At the end of the countdown, the ninth output will go to zero and turn off the load. And at output 10, a unit will appear, which will stop the counter.

The timer circuit is started by pressing one of the three buttons with fixing the time interval, while it starts the countdown. Parallel to pressing the button, the LED corresponding to the button lights up.


At the end of the time interval, the timer emits an audible signal. A subsequent press will disable the circuit. Time intervals are changed by the denominations of the radio components R2, R3, R4 and C1.

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

The timer circuit works as follows. In the initial state, the capacitor C1 is discharged, both transistors are closed and the load is de-energized. With a short press on the Start button, the gate of the second transistor is connected to a 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 occurred on it through the capacitor C1 enters 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 the capacitor C1 is charged through the resistor R1, the voltage across it rises, and at the gate of the first transistor (relative to the common wire) it decreases. After some time, depending mainly on the capacitance of the capacitor C1 and the resistance of the resistor R1, it decreases so much that the transistor starts to close and the voltage at its drain rises. This leads to a decrease in the gate voltage of the second transistor, so the latter also begins to close and the voltage at the load decreases. As a result, the gate voltage of the first transistor begins to decrease even faster.

The process proceeds like an avalanche, and soon both transistors close, de-energizing the load, the capacitor C1 quickly discharges through the 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 allowable voltage between the gate and source is 20 V, the device can operate at a supply voltage of 5 to 20 V (nominal voltage of capacitor C1 should be a few volts more than the supply). The turn-off delay time depends not only on the parameters of the 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 about 1.5 times (with the values ​​of the elements indicated in the diagram, it was 50 and 75 s, respectively).

If, with closed transistors, the voltage across resistor R2 turns out to be more than 0.5 V, then its resistance must be reduced. A device that provides a turn-on delay can be assembled according to the circuit shown in Fig. 2. Here, the assembly transistors are connected in much 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), the capacitor C1 is discharged and both transistors are closed, so the load is de-energized. As it charges through resistors R1 and R2, the voltage on the capacitor rises, and when it reaches a value of about 2.5 V, the first transistor begins to open, the voltage drop across resistor R3 increases and the second transistor also begins to open. When the voltage at the load rises so much that the diode VD1 opens, the voltage across the resistor R1 rises. This leads to the fact that the first transistor, and after it the second one, open 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 the capacitor C1). The timers are mounted on printed circuit boards made of fiberglass foiled on one side, the drawings of which are shown respectively in Fig. 3 and 4. The boards are designed for the use of a diode of the KD521, KD522 series and parts for surface mounting (resistors R1-12, size 1206 and a tantalum oxide capacitor). Setting up devices is reduced mainly to the selection of resistors to obtain the required time delay.

The described devices are designed to be included in the positive power cable of the load. However, since the IRF7309 assembly contains transistors with a channel of both types, it is not difficult to adapt the timers to include in the negative wire. To do this, the transistors should be swapped and reversed by switching on the diode and capacitor (naturally, this will require corresponding changes in the printed circuit board drawings). It should be noted that with long connecting wires or the absence of capacitors in the load, pickups on these wires and uncontrolled activation of the timer are possible.

Timer circuit for five minutes

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

After a short circuit SB1, the capacitance C1 starts charging, which is included in the collector circuit of the transistor VT1. The voltage from C1 is supplied to an amplifier with a large input impedance on transistors VT2- VT4. Its load is an LED indicator that turns on alternately after a 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 mains at the start of the countdown and 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 microcircuits K561LE5. The generation frequency is formed by an RC chain on R1,C1. The accuracy of the course is adjusted over the shortest time interval, by selecting the resistance R1 (temporarily, when adjusting, it is desirable to replace it with a variable resistance). To create the necessary time ranges, the pulses from the output of the multivibrator go to two counters DD2 and DD3, as a result, the frequency is divided.

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


When a logical unit 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 unit signal follows 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, zeros are set at their outputs, including the output on which the SA2 switch is installed. At the input of DD1.3, zero is also supplied and, accordingly, a unit is output at its output, which connects the load to the network. Also in parallel and at the input 6 DD1.2 will be installed zero level, which will start the multivibrator and the timer will start timing. The timer is powered by a transformerless circuit, consisting of components C2, VD1, VD2 and C3.

When the toggle switch SW1 is closed, the capacitor C1 begins to slowly charge through the 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 output will drop to zero, and the circuit with the bulb will open.

With a resistance of resistor R1 of 10M (0.25 W) and capacitance C1 of 47 uF x 25 V, the device will operate for about 9 and a half minutes, if desired, it can be changed by adjusting the ratings 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 a light bulb even when the toggle switch is closed. The quiescent current of the design is only 150 μA. Transistor BD681 - composite (Darlington) medium power. Can be replaced by BD675A/677A/679A.

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

This simple homemade timer allows you to delay the turning off of a mains powered lighting or heating device for a certain time. The timer circuit is simple and easy to repeat even by novice radio amateurs. It is based on a voltage comparator on a DA1 chip, the load of which is the relay winding. The exposure time depends on the capacitance of the capacitor C3 and the resistance of resistors R1 and R2. The power supply is a transformerless one with a ballast capacitor C1, the supply voltage is maintained unchanged by a zener diode VD3.

Timer operation. In the initial state, the timer and the load connected to socket X2 are de-energized. When the SB1 button is pressed, the mains voltage of 220 V through its contacts SB 1 1 is supplied to the timer and load, and the contacts SB 1 2 connect the capacitor C3 of the timing circuit to the power source. The capacitor instantly charges, the voltage at the control input of the microcircuit (pin 1) becomes greater than the threshold (about 2.5 V), and it opens. At the same time, relay K1 is activated and with its contacts K 1.1 blocks the contacts SB1 1 of the button, after which it can be released - the load will remain connected to the network. After opening the contacts SB 1.2, the capacitor C3 begins to discharge through the resistors R1, R2 and the voltage across it gradually decreases. At the moment when it becomes less than the threshold, the microcircuit closes, the relay releases and its contacts disconnect the load from the network. With the resistor R2 fully inserted into the discharge circuit and the capacitance of the capacitor C3 indicated on the diagram, this will happen approximately 3 minutes after the button is released. Reducing the exposure time is achieved by reducing the resistance of the introduced part of the resistor R2. The maximum exposure time can be increased by replacing the capacitor C3 with another one with a larger capacity.

Timer details. They are mounted on a printed circuit board made of foil fiberglass. The relay is electromagnetic with a voltage and a current of operation, respectively, not more than 12 V and 50 mA, with contacts designed for switching voltage of 220 V at the current consumed by the load.

The timer board is placed in a housing made of insulating material, the SB1 button, a socket and a variable time adjustment resistor are installed on its walls in convenient places. A control knob with a pointer is fixed on the resistor shaft. Establishing a timer comes down to calibrating the scale of a variable resistor in units of time. The device has been repeatedly successfully assembled and tested.

This timer project can be used to turn on or off any device after a given time, the circuit can be used in many cases, such as turn on / off the radio, TV, fan, pump, lighting, electric heater.

The project was developed on the basis of two CMOS chips CD4001 and CD4020. Two elements CD4001 form a generator, a transistor BC547 needed to control the relay, which, in turn, turns the load on and off. The circuit is quite simple, it has jumpers for setting the required time interval, Preset - a regulator for setting the generator frequency to 1 Hz. SW1 - button, SW2 - on / off circuit. Relay switch contacts can handle load with 220V 5A. Figure printed circuit board.

Timer parameters and details

  • Power: 12V DC
  • Current consumption: 60mA
  • D3: power indicator
  • D2: timer operation indicator
  • CN2: power input
  • J1-J7: Setting the duration time on/off
  • CN1: relay output
  • SW1: Start button
  • SW2: Power Button On/Off
  • PR1: Accuracy setting

Parts list

The table above shows which jumper position corresponds to which cycle times. You can make a switch and bring it outside, or you can immediately solder the desired position, depending on the application. The maximum period is 2 hours. This means that a connected, say, electric heater will work for 2 hours and rest for 2 hours. If you need to increase the cycle even more, you will need to lower the generator frequency to 0.5 Hz. Then the period will be proportionally lengthened and become 4 hours.