Time relays with their hands: how to build their own

Activate and deactivate home appliances can be without the presence and participation of the user. Most manufactured nowadays models equipped with time switch for automatic start / stop.

What if just want to manage obsolete equipment? Patience, our advice and make time relays with their own hands - believe me, this will be used in homemade farm.

We are ready to help you carry out an interesting idea and try your hand in the way of an independent electrical engineering. For you, we have found and organize all the valuable information on the options and methods of manufacturing the relay. The use of the information provided ensures ease of assembly and excellent operation of the device.

In the proposed article to the study discussed in detail tested in practice, home-made variants of the device. Data are based on the experience of passionate masters in electrical engineering and standards requirements.

The content of the article:

  • Scope of the time relay
  • Schemes of different homemade
    • Option # 1: The easiest transistors
    • Option # 2: based on the chips
    • Option # 3: a power output of 220 V
  • Conclusions and useful videos on the topic

Scope of the time relay

Man has always sought to make their lives easier by introducing into use various devices. With the advent of technology on the basis of the motor there was a question about the equipment of its timer, which would run the equipment automatically.

Included in the set time - and you can go do other things. The unit itself after a set period of shut down. But for this automation and took the relay with the self-timer function.

A classic example of the device in question - in this relay in the old Soviet-style washing machine. On its body had a pen with multiple divisions. Exhibited the desired mode, and the drum is spinning for 5-10 minutes until the inside watch will not reach zero.

Factory-delay relay

Electromagnetic relay time small in size, consumes little power, has no moving parts breaking and durable

Today time-delay relay set in a different technique:

  • microwave ovens, ovens and other appliances;
  • exhaust fans;
  • automatic watering system;
  • automatic lighting control.

In most cases, the device is made based on a microcontroller, which simultaneously controls all the other modes of the automation technology. The manufacturer is cheaper. No need to spend money on several separate devices, responsible for one thing.

By type of element output time switches are classified into three types:

  • Relay - load is connected through a "dry contact";
  • tRIAC;
  • thyristor.

The most reliable and resistant to bursts in the network the first embodiment. A device with a commuting thyristor output should be taken only if the connected load is not sensitive to the shape of the supply voltage.

To make your own time switch, you can also use a microcontroller. However, homemade mainly made for simple things and work environment. Dear programmable controller in such a situation - a waste of money.

There is a much simpler and cheaper in the performance of the scheme on the basis of transistors and capacitors. Moreover, there are several options to choose for their specific needs there are plenty.

Schemes of different homemade

All offered production versions with their own hands the time switch based on the principle set delay start. First, a timer is started with a predetermined time interval and countdown.

an external device connected to it starts to work - motor or light activated. And then, upon reaching zero, relay outputs the trip signal of the load current or overlaps.

Option # 1: The easiest transistors

Schemes based on transistor performance - the easiest to implement. The simplest of these involves a total of eight elements. To connect them do not even need a board, all you can solder without it. Such relays are often made to connect through lighting. I pressed a button - and the light is on for a couple minutes, and then turns off itself.

Typical scheme

To supply this scheme requires the battery to 9 or 12 volt battery, such as a relay can be powered from the variable 220 through the inverter to the permanent 12 (+)

To pick it up a homemade timer, you need:

  • a pair of resistors (100 ohms, and 2.2 m?);
  • KT937A bipolar transistor (or analogue);
  • load relay switch;
  • variable resistor 820 ohms (for adjusting the time interval);
  • capacitor 3300 uF and 25 V;
  • KD105B rectifier diode;
  • switch to start the countdown.

The delay time in the relay timer is due to the charging of the capacitor to the transistor level power key. While C1 is charged to 9-12 in the key in the VT1 remains open. External supplying the load (light lit).

After some time, which depends on the set value R1, the transistor VT1 closure occurs. Relay K1 is de-energized as a result, and the load is disconnected from the voltage.

C1 capacitor charge time is determined by the product of its capacitance by the total resistance of the charging circuit (R1 and R2). Wherein the first of the fixed resistances and the second adjustable for setting a specific range.

Time parameters for the assembled relay chosen empirically exhibiting different values ​​for R1. To subsequently make it easier to carry out the desired setting time, the housing should be done with per-minute layout positioning.

Issued to specify the formula for calculating the delay for this circuit is problematic. Much depends on the specific parameters of the transistor and the remaining elements.

Reduction of the relay to its initial position is performed by switching the reverse S1. Capacitor shorted to R2 and is discharged. After restarting S1 cycle starts anew.

More stable circuit two transistors

One transistor of the chain can be replaced by a pair of similar, only that enhance stability of the collected time relay (+)

In the circuit with two transistors, the first involved in the regulation and management of the temporary pause. The second - an electronic key to turn on and turn off the power at the external load.

Driving on four transistors

In an embodiment with a dual scheme is one of the key B1 "starts a timer" and includes the load, and the second B2 disconnects its (+)

The hardest part of this modification - it's just pick the resistance R3. It must be such that the switch is closed only when the signal supply to B2. Thus inverse insertion load is obliged to occur only when triggered B1. It will have to pick up experimentally.

Circuit with FET output

To increase the time delay relay interval KT937A can be replaced by a field effect transistor with insulated gate (e.g., 2N7000) (+)

This type of transistor gate current is very small. If the resistance of the coil in the control relay to pick up a large vein (in the tens of ohms and megohms), the shutdown interval can be increased up to several hours. And most of the time relay timer virtually no power.

Active mode it begins in the last third of the interval. If PB connected through a conventional battery, then it will last a very long time.

Option # 2: based on the chips

In transistor circuits have two main disadvantages. For them difficult to calculate the time delay and before the next start-up is required to discharge the capacitor. Using the chip eliminates these disadvantages, but complicates the device.

However, if there is even the minimum skills and knowledge in electrical engineering to make their own hands like time relay is not a problem.

The timer on the chip TL431 Series

If the delay is required in the range from ten minutes to an hour, the transistor chip is best replaced TL431 series (+)

TL431 opening threshold at more stable due to the presence within the reference voltage. Plus for its switching voltage required is much greater. At maximum, by increasing the value of R2, it can be raised to 30 V.

Capacitor to such values ​​will be charged for a long time. In addition, the C1 connection resistance to discharge in this case takes place automatically. Additionally press the SB1 is not necessary.

Another option - is the application of "integral timer» NE555. In this case, the delay is also determined by parameters of the two resistors (R2 and R4) and a capacitor (C1).

"OFF" switch is due to the switching of the transistor again. Just close it is performed on a signal output from the chip when it has counted the desired seconds.

Using IC NE555

"Timer" based on the NE555 chip was very similar to the classic version of a single transistor, but delay interval here is set more detailed (from 1 second to several minutes or hours) (+)

False positives when using chip out much less than when using transistors. Currents in this case controlled by tighter transistor opens and closes exactly when required.

Another classic option microcircuit time switch based on the basis of KR512PS10. In this case, when the power circuit R1C1 supplies the reset pulse input circuits, whereupon the internal clock runs in it. Off frequency (division ratio) of the latter sets regulating circuit R2C2.

The number of counted pulses is determined by switching five terminals M01-M05 in various combinations. The delay time may be set from 3 seconds to 30 hours.

After counting the number of pulses of said output circuit Q1 is set high, opening VT1. As a result, relay K1 and enables or disables the load.

Relay-based chip KR512PS10

Driving assembly time switch via KR512PS10 chips are not complicated, resetting in This PB occurs automatically when the preset parameters by connecting the tabs 10 (END) and 3 (ST) (+)

There are even more complex circuits the time switch based on microcontrollers. However, they are not very suitable for self-assembly. Here the impact of complexity with both soldering and programming. Variations of the transistors and the simplest chips for home use is enough in most cases.

Option # 3: a power output of 220 V

All of the above circuits are designed for 12-volt output voltage. To connect to the assembled based on these timing relays powerful load, you need to exit installing magnetic starter. For motor control or other complex electrical appliances with high power and will have to do.

However, to adjust the domestic lighting can be collected on the basis of the relay diode bridge and a thyristor. At the same time connect anything else is not recommended by a timer. Thyristor passes through it only positive part of the sine wave variables 220 volts.

For incandescent bulbs, fan or heating element is not terrible, and other electrical equipment such can not stand and burn.

Time delay relay 200

Scheme time switch with a thyristor and at the output of the diode bridge at the input is designed to work in networks 220, but has some limitations on the type of the connected load (+)

To build such a timer for light bulbs necessary:

  • constant resistance 4.3 Mohm (R1) and 200 ohms (R2) plus controlled at 1.5 ohm (R3);
  • four diodes with a maximum current greater than 1 A and the inverse voltage of 400 V;
  • 0.47 uF capacitor;
  • thyristor VT151 or equivalent;
  • switch.

It operates the relay-timer of the general scheme for such devices, with the gradual charging of the capacitor. When closing on contacts S1 C1 starts charging.

During this process, the thyristor VS1 remains open. As a result, the load line voltage L1 220 goes V. After charging thyristor C1 closes and cuts off the current by turning off the lamp.

setting a delay adjustment is made on the values ​​R3 and capacitor selection. At the same time we must remember that any touch to the bare legs of all the elements used threatening electric shock. They are all under the voltage of 220 V.

If there is no desire to experiment and engage in self-assembly of time switch, you can choose ready-made versions of switches and sockets with timer.

Learn more about these devices is written in the article:

  1. Switch off timer: how it works and what kind is best to choose
  2. Socket with timer: types, working principle features installation +

Conclusions and useful videos on the topic

To understand from scratch in their internal timer relay is often difficult. Some have not enough knowledge and experience of others. To simplify your selection of a desired circuit, we made a selection of videos, which gives details of all the nuances of the work and the assembly considered electronic device.

The operating principle of the time switch elements at the transistor key:

The self-timer FET load 220:

Step by step the production of the relay delay with his own hands:

Assemble your own time switch is not too difficult - there are several schemes for the implementation of this plan. All are based on the gradual charging of the capacitor and the opening / closing of the transistor or thyristor output.

If you want a simple device, it is best to take a transistor circuit. But to accurately control the delay time will have to solder one of the options on a given chip.

If you have experience in the assembly of such a device, please share the information with our readers. Leave comments, attach photos of their homemade and participate in discussions. Communication unit located below.

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