Most control systems that use mobile communication are based on the connection of the microcontroller with the phone's serial port, or use the Caller ID subscriber function, or receive control commands via SMS messages. Such control systems require complex electronic devices and work with a certain type of phone model.

D. Hill (England) has developed a scheme for remote control of household appliances using a mobile phone, in which the glow of the phone screen is used as a control signal. The design of the device is much simpler than existing systems using mobile communications, is cheaper to manufacture, and can work with any type of mobile phone. Another advantage of this remote control is that the phone does not have to answer the call, so there are no costs for using the telephone network.

The principle of operation of the device is very simple. When a call signal arrives on a mobile phone, its screen starts to glow, the light-sensitive resistor LDR, attached to the screen, detects a glow. The change in the resistance of the resistor is the trigger signal for the switching circuit.
The circuit is based on a double flip-flop 4013, its two outputs change state with the appearance of a high-level pulse at the TRIGGER input. A photosensitive resistor LDR1 is placed in front of the phone screen. The sensitivity of the resistor LDR1 is adjusted by the potentiometer VR1. When the phone receives a call signal, the screen lights up, the resistance of the resistor LDR1 drops, and the transistor TR1 opens. Capacitor Cl acts as a smoothing capacitor that keeps the trigger input continuously high even if the mobile phone screen flickers when a call comes in.
Resistor R2 pulls trigger input IC1 low and also discharges capacitor C1 when the phone does not receive a call.
Transistor TR2 is controlled by output Q1 of IC1 and is used to turn on and off the relay RLA1, whose contacts switch the power supplied to the load.
LEDs D1 and D2 indicate the state of the relay, diode D3 protects the circuit from reverse transients in the coil.
A switch from the lzm series or any other S1 brand can be used to manually switch the relay.
A mobile phone with a photosensitive resistor must be placed in a light-tight housing.

A significant drawback of the scheme is the danger of the device being triggered by an accidental call or when someone dials the wrong number, etc.
Therefore, it remains relevant to refine the author’s idea, for example, you can refine the device circuit and use two phones (the probability of simultaneous random dialing of two different numbers is very low) or refine the device with a counting device, which, for example, after 3 calls within 30 seconds, will switch the relay .

In some cases, it becomes necessary to remotely turn on and off any load, device, for example, control the lighting of a house to create the effect of the presence of residents, or turn on any device in advance.

Cell phone manages the load

At present, the cellular communication channel is the most convenient channel for remote control. Now there are many different devices built on microcontrollers and working via SMS, or made on specialized microcircuits that understand the commands of the phone buttons. But all this can be too complicated for a simple case when you only need to turn one load on and off. Such a device should consist of a cell phone and a trigger, with a relay output.

It should respond to a call signal. And there must be a delay at the input of the trigger. The fact is that advertising in the form of SMS messages periodically comes to any cell phone, while there is a short ringing signal. So, the delay is needed so that the trigger does not work on a short signal, but only on a significantly longer one that comes with an incoming call. Now the second question is how to connect the cell phone to the trigger? Very unregulated. If the duration of the display is more than the charging time of C1, then the voltage on C1 reaches a logical unit and the Schmitt trigger on the elements D1.3 and D1.4 switches.

If the duration of the display is less than the charging time of C1, then the voltage on C1 does not reach a logical unit and the Schmitt trigger on the elements D1.3 and D1.4 switches, and the capacitor itself is rapidly discharged through VD1 and R3. Now let's move on to the actual trigger that controls the relay. It is made on the D2 chip. This is a D-flip-flop, included according to the scheme of a single-digit counter. Its state is reversed each time an impulse arrives at its "C" input.

And so, at the moment the power is turned on, the trigger D2 is set to a single state by the RC circuit R7C2, which, at the moment the power is turned on, generates a pulse at its pin 6. In a single state, the inverse trigger output pin 2 will be a logical zero. Transistors VT1 and VT2 are closed, relay K1 is off. This is the original state. If now they called once and the duration of the call was sufficient to generate a pulse at the output D1.3, then the trigger D2 goes into the opposite state, a logical unit is set at its inverse output. The VT1-VT2 key opens and the K1 relay turns on the load with its contacts (not shown in the diagram).

When you call again (if the duration of the call was sufficient to generate a pulse at the output D1.3), the trigger D2 goes into its original state, zero is set at its inverse output. The key VT1-VT2 closes and relay K1 turns off the load with its contacts. A power supply with a voltage of 5 ... 6V, as such, you can use a charger for a cell phone, "figuring out" a tee. Or power the circuit from any other current source of the same voltage. Relay K1 with 5V winding. Installation can be performed on a breadboard printed circuit board, and clamps for fastening a cell phone that will work with it in pairs can also be provided on it.

Microcircuits can be replaced by foreign analogues (shown in the diagram). Chip D1 of type K561LE5 is used here as a set of inverters, so it can be replaced by any other with at least four inverters, for example, K561LA7, K561LN2. The relay can be replaced by any with a 5V winding, suitable for the power of the contacts for switching a specific load. You can also use a relay with a winding for a higher voltage, but this will require a corresponding increase in the supply voltage. The supply voltage can be in the range from 5V to 15V. Naturally, if it is greater than the output voltage of the cell phone charger, the circuit will require a separate power supply.

Establishment comes down to setting the photosensor with resistor R1. It is necessary to cover the photoresistor with a cardboard box and adjust R1 so that the output of D1.2 is a logical zero. It is possible that you will have a photoresistor of a different type or nominal resistance, and it is quite possible that you will have to replace the resistor R1 with a resistor of a different resistance. Then, you need to put the photoresistor with a working surface on the cell phone display. Can be attached with clear tape.

Then cover this design with a cardboard box, and call a cell phone. In this case, its output D1.2 should be a logical unit. The next step is to adjust R5. First, set it to the maximum position. Then call this cell phone and "wait for an answer" until the D1.3 output is zero. If the call reset occurs earlier, reduce the resistance R5. Then, send SMS, D1.3 output zero should not appear, otherwise increase R5 a little.

Today you will learn how to make a homemade gsm alarm from a cell phone. Such a security system can guard your cottage, garage or car.

This article has been planned for a long time, it is a "mobile GSM add-on" to . After reading the article to the end, you will learn how to make a cellular alarm out of any existing alarm system, but more on that later ..

This add-on implements the notification function on a cell phone and allows the owner to control the situation about the "integrity" of the protected object anywhere in the world using mobile communications. Such an alarm system is the cheapest option and requires only an old cell phone, a battery + a few parts, solder and free time from the investment.

Materials and tools required for the manufacture of GSM alarms:

• Nokia 1100 cell phone (or any other mobile phone with a quick call function that !Attention! implemented by a single button pressed and held in this position).
• headset (earphone with microphone) is used for audio control of the room
• soldering iron
• solder
• the wire
• reed switch (or push-button sensor for opening the door)
• 12 Volt acid-gel battery (the larger the capacity, the longer the “autonomy” in case of a 220V power outage)
• battery charger

The principle of operation of homemade mobile signaling based on cellular

Ways to connect a cell phone to the alarm:

The methods described above to establish the interaction of a security alarm and a cell phone are valid for any alarm. Thus, you can “attach” the GSM notification to any alarm you have (for example, to a regular car alarm). Only one thing is required of her: to close the relay contacts, or to apply 12 volts during the “operation” (for example, you can take 12 volts from the terminals of the car siren only then you will need to set up the “quiet mode” so that when arming and disarming the alarm does not “ quacked "based on what option you have - choose the appropriate scheme.

How to organize an uninterrupted power supply for GSM alarms.

We figured out how the alarm system interacts with a mobile phone, it remains to solve one more question - to provide power to the phone in an uninterrupted mode 24 * 7, several options are possible here:

In the future, I plan to write a series of articles on the topic of security systems: how to make a security complex from a video recorder with internet notification and an article about the types of sensors for which will help make the protection of your apartments, garages, summer cottages more complete and reliable.

I wish you success in creating an alarm, as well as the safety of your property!

The remote control circuit allows you to turn various appliances on and off via a telephone line. The scheme does not have range restrictions inherent in devices using radio or IR channels.

The scheme described here allows you to turn on up to nine devices, in accordance with the numbers 1 ... 9 on the phone's dial pad. For control tone (DTMF) parcels of the telephone set are used. The number "0" in the tone mode is used to switch between the control and normal (conversational) modes of the phone. Thus, the telephone can be used to control external devices while retaining the functions of a conventional telephone.

The circuit uses KT3170 chips (DTMF to BCD converter), (dmultiplexer 4-16) and 5 CD4013 dual D-flip-flops. The scheme works as follows.
After the connection is established (hearing ringing beeps in the handset), you must press "0" in tone mode (DTMF). IC1 decodes "0" to code "1010", which is further demultiplexed by IC2 to output O10 (pin 11). The active-low output after inversion by gate IC3 (CD4049) becomes "1", which switches flip-flop 1 and through transistor T1 energizes the coil of relay RL1. Relay RL1 has two changeover contacts: RL1(a) and RL1(b). A closed contact RL1(a) shunts the telephone line with a 220 Ohm resistor, while a 10 kHz audio signal is sent through RL1(b) to the line, informing the caller that the phone is in control mode. The 220 ohm resistor disconnects the caller from the conversational telephone circuit. The telephone line is now in control mode.

If, after the connection is established, the number "0" is not pressed, the ringing signal will continue to sound, and the phone can be used for normal conversation. If the number "1" is pressed in the control mode, the IC1 decoder will respond to it with the code "0001". The output of the demultiplexer, inverted by the CD4049 gate, will switch the corresponding flip-flop to the opposite state. The trigger output will turn on the relay (RL2) which can turn on / off the load connected to its contacts. Other digits can be used to control other appliances.

Upon completion of the load transfer, the 220 ohm resistor must be disconnected from the telephone line and the 10 kHz tone removed. To do this, press “0” again (in tone mode) to switch trigger 1 to its original state and turn off the RL1 relay. The phone line will be free again and ready to receive normal calls. The circuit should be connected in parallel with the telephone set.

• It will be interesting to know the opinion of specialists on telephone lines. Is this scheme compatible with Russian lines? Will it work without the "auto-up" of the tube?
• I am not a specialist, but when I collected my first AON, I almost became one. Since then, the standard has changed. If this were the case, then it turns out that it is possible to transfer information (though not for long) and not pay anything for it. Organize a free fax, messaging ... Modern callers determine the number before picking up the phone. At the same time, 24V is kept in the line, see the article http://cxem.net/telefon/2-57.php At the same time, AON exchanges information with the first substation. But these signals are not heard in the handset of the first telephone. So the First substation is blocking his signals (except for the call signal).
• About 5 years ago I assembled such a device on an AVR (90S2313, 1008VZh18, 155ID3). The device picked up the phone after 3 rings, a session was conducted (the number of control outputs was 16) and then the whole process was controlled (for example, to end the connection, it was necessary to press #). Then there was a variant on the mega (without ID3). The line was not of the best quality, but the device worked well. PS: if anyone needs it, I can try to find a draft of the circuit
• After the 3rd call will raise with any incoming? Then time will wind up in vain for callers. AON Rus with good firmware 10 years ago, and now even more so, it will be able to turn on auto-raising only to specified incoming numbers, for example, only to your mobile. I gave him numbers from which I could call. He called home, entered the password and could remotely control the phone, change settings, listen to incoming messages.
• Agree. But in my design it was not necessary (because let's say it was a "secret" line with a number). Those. this is not a home device (used in production). Even if the device lifted the pipe, then you can control the outputs by knowing a certain password.
• Yes, I also assembled a similar device, only on a PIC. Satisfied with the work. example of use and implementation. http://www.yakorev.com.ru/dtmf485.html I also used DTMF signal decoders to control a PTZ video camera, both by radio and wires. The diagrams have not survived.
• The description says a 220 ohm resistor shunts the line, this is also an auto-lift. And most importantly, it seems that if you don’t press 0 a second time, the phone will remain with the handset raised, there is nothing to track the busy signal there.
• good evening, everyone is interested to know this device will work if you tie it to a cell phone:confused:who knows:confused:
• Cell phone messages do not match the DTMF code and will not be accepted by the device. For control, you will need to use [B] DTMF BIPPER I.e. send DTMF signals over the acoustic channel of a cell phone.
• I explain as a specialist with 40 years of experience. When a call is sent, in all modern stations the conversational path is not directly turned on, so no signals can be transmitted through it! Also, a 10 kHz signal will not pass through the conversational path. The frequency band transmitted over the speech path is 0.3-3.2 kHz, everything else is cut off by the filter. Therefore, you should do it as in the old caller ID (turn on after 3 calls, turn off after a time delay). If you think, then it’s easy to redo.

The device (hereinafter referred to as the remote control) is designed for remote control of any device with a simple operation algorithm. Simply put - this is a remote switch (or switch) using a cell phone. In this case, the phone can be any, since the device is not connected to it galvanically.

Main technical characteristics:

• Supply voltage 12 volts
• Three possible modes of interaction with the control object
  - turn on for 3 seconds
  - turn on for 10 seconds
  - shutdown for 10 seconds
• Galvanic isolation from the controlled device
• Controlling the transition of the phone to receive mode
• Schema health monitoring

Schematic diagram of remote control:

Description of the scheme

This circuit uses a phone operation sensor assembled on the elements L1, C1, R1, VT1, R2, which is the simplest electromagnetic field detector with low sensitivity. The operation of the phone in the receive mode on the oscillogram taken from the sensor is clearly visible.

The microcontroller works out the following algorithm when the phone receives a call: having received the first impulse, it goes into standby mode and after 15 seconds checks again whether the impulse comes from the sensor. If not, then it goes back to the beginning of the program, if there is an impulse, it turns on or off the relay for a given interval. Thus, some noise immunity and filtering of technological checks from the operator, as well as signals from SMS are achieved.

It may seem to you that protection against accidental operation is insufficient, but as practice has shown, this is more than enough. A remote computer worked with this scheme for about 3 years, which sometimes had to be restarted in this way. The computer was located on the other side of the city and worked in a technological room in a 9-storey building. It was not interesting to drive to restart it and spend a couple of hours on it, and restarting with the phone solved the problem in most cases. Of course, there are special devices for such cases, but, as practice shows, they cannot always solve the problem and are often not economically feasible. You can manage not only a computer - only imagination limits the options.

The relay operation time interval is set by switching SA2:
1. submission time log. 1 - 3 seconds
2. submission time log. 1 - 10 seconds
3. submission time log. 0 - 10 seconds

Switch SA1 simulates a triggered sensor. VD1 duplicates the pulses at the input of the microcontroller.

Used radioelements in the circuit. Interchangeability

Transistor VT1 can be mps9014, BC547. VT2 can be replaced by any medium power reverse conduction transistor. Select a 12 volt relay with contacts of sufficient power to control your device. Chip 78L05 can be replaced by 7805. Choke can use SMD.

The configuration bits are already written in the firmware file.

Device setup

Setting up the device comes down to flashing the controller and setting the sensor sensitivity level with resistor R1. It is enough that he would react to the phone from a distance of 3-5 cm.

The cost of parts to create such a device is about $3.

You can download the firmware and PCB file in LAY format below

List of radio elements