How does a refrigerator door open sensor work? Notes for the master - home household alarms

Refrigerator open alarm

The peculiarity of this signaling device is that it does not connect to the electrical circuit of the refrigerator in any way. This is just a small box that is placed inside the refrigerator. When the refrigerator door is open, the interior lamp turns on. The light from it hits the photodiode VD 1 and its resistance decreases sharply, the circuit in Fig.1.

Fig.1

Capacitor C1 begins to charge through the reduced resistance of the photodiode. After some time, the voltage on C1 reaches the level of a logical unit and a "tandem" of two multivibrators is launched, one of which operates at an audio frequency ( D 1.3 - D 1.4), and the second on the infrasonic ( D 1.1 - D 1.2). Connected between input and output element D 1.4, the piezoelectric sound emitter starts to beep intermittently, indicating that the refrigerator door is open for more than the charging time for C1 to a logic unit voltage.

When the refrigerator door is closed, the resistance VD 1 is high and the voltage on C1 is low and the signaling device is “silent”.

The signaling device is powered by the Krona battery. The battery has enough energy for at least one year of operation of the device.

Adjustment is to adjust the resistor R 2 so as to obtain the desired characteristics (time delay, response threshold).

The tone of the sound can be set by selecting R 3, and the interrupt frequency is R1.

J. Radio constructor

No. 12, 2004

Miniature plant watering alarm

The device shown in Fig. 2 signals that the earth in the flower pot has dried up and the plant needs to be watered., while the indicator (LED VD 2 ) shines at maximum brightness.

Fig.2

As soil moisture increases, the brightness of the LED gradually decreases, and it goes out completely. resistor R3 the brightness of the indicator of the desired humidity level is adjusted.

The circuit uses the K561TL1 chip. On elements DD 1 assembled a rectangular pulse generator. From the entrance DD 1 signal is fed to the electrode P1 and through the inverter DD 2 to electrode P2. Elements DD 3 and DD 4 control the LED. The rectangular pulses are designed to prevent oxidation of the electrodes. Long nails can be used as electrodes.

Load disconnection signaling device

The circuit signals with a luminous LED about the on state of the load, and an audible signal about the fact of the load being disconnected (or about a break in it, about a power outage), Fig.3.

Fig.3

On the direct resistance of several diodes connected in series to the load, some voltage drops. As long as the load is receiving power, this voltage is present. It is rectified by a diode rectifier. VD 10 and capacitor C1, and serves as power for the indicator LED HL 1. And also, it charges the capacitor C2, which serves as a power source for the microcircuit D1.

On chip D 1 made a sound generator. While on conclusion 5 D 1 high voltage is supplied, the generator is blocked. When the load or supply voltage is turned off, the voltage on C1 quickly decreases due to the discharge through the LED. In this case, the charge of the capacitor C2 is not consumed so quickly, since the diode interferes with this VD 11 and low current consumption chip D 1. Supply voltage D 1 is maintained, but the voltage at output 5 drops D 1. As a result, the sound generator and the piezoceramic sound emitter are launched bf 1 sounds for a while while it is powered by the charge of capacitor C2.

When the load is turned on, C1 charges quickly and blocks the sound generator.

The setting consists in selecting the number of diodes VD 1-VD 8.

D1 - chip K561LE5.

Kuzyansky L.

Literature:

1 Piet Germing. Automatic Lighting Swith

Elektor, No. 7-8, 2008.

Mains voltage failure signaling device

In any locality, short-term interruptions, "failures" of voltage in the network occur. Their duration can vary from fractions of a second to several seconds. Relatively long dips are visually noticeable - the lighting "blinked". Shorter ones go unnoticed, but may well cause the TV to switch from working to standby mode or crash the computer. It often remains unclear whether the failure occurred due to a malfunction of the device or a short-term failure of the mains voltage was the cause. The cause of both irregular and frequent short dips can be a malfunction of the contacts in the socket or plug (poorly clamped wires, weak spring contacts, oxidation of the contacts), a violation of the integrity of the cores of the stranded wire in the power cord, wear of the switch contacts.

To understand where to look for a malfunction, the proposed device will help - a signaling device for a network voltage failure. First of all, it must be plugged into a free outlet, not the one that includes the network plugs of the TV or computer. If the entire network of an apartment, office or building is faulty, then at the first voltage drop, the alarm LED will turn on. If this does not happen, but a failure occurs, it is likely that the socket to which the malfunctioning device is connected, its plug or power cord is faulty.

The next step is to connect the signaling device and the TV (computer) through a tee to the same outlet. If now the LED turns on, it means that the socket in the wall or the tee is junk. Otherwise, it remains to check the plug and power cord of the TV (computer). If they are serviceable, you will have to look for a defect in the device itself, which is prone to failures.

The diagram of the signaling device is shown in Fig.4.

Fig.4

On transistors VT1 and VT 2, the equivalent of a thyristor is assembled. When the signaling device is initially connected to the network or after an interruption in the mains voltage, the "thyristor" remains closed, and the LED HL 1 on because the transistor VT 3 open by base current flowing through resistors R5 and R 7. After pressing the button SB 1 "thyristor" will open, the voltage drop across it will become insufficient to keep the transistor open VT 3 with an LED included in its emitter circuit. The transistor will be closed and the LED off. In this (standby) state, the device will remain until the next failure of the mains voltage, as a result of which the “thyristor” will close and the LED will turn on.

The mains voltage is reduced to approximately 23 V by a resistive voltage divider R1-R 3. This made it possible to apply in a rectifier bridge VD 1-VD 4 relatively low voltage diodes. The capacitance of the smoothing capacitor C1 indicated in the diagram was selected experimentally. Its decrease leads to dips in the rectified voltage at the moments when the mains sinusoid passes through zero and false alarms of the signaling device. Excessive capacitance of this capacitor increases the minimum duration of detectable dips. Ceramic capacitor C2 and inductor L 1 eliminate impulse noise that can open the "thyristor" and turn off the LED before its inclusion is noticed.

Zener diode VD 5 ensures reliable operation of the signaling device at increased mains voltage. However, even when it breaks, the voltage across the diodes VD 1-VD 4, capacitors C1, C2 and other parts of the signaling device due to the resistive divider R1-R 3 does not go beyond the limits allowed for them. To reduce the risk of electric shock in case of accidental contact with parts of the signaling device, R1 and R 3 voltage dividers are included in both network wires. Their total resistance is chosen so that the average current of the "thyristor" or the LED cannot exceed 9 ... 10 mA, even if the resistor is broken at the same time R 2 and Zener diode VD 5. The power consumed by the signaling device does not exceed 2 W.

Instead of KD522V diodes, any of the KD521, KD522 series will do. Throttle L 1 - homemade, 40 turns of any insulated thin wire on any ferrite magnetic core. A ready-made choke DM or PDM is also suitable for the inductance indicated on the diagram. A replacement for the D814A zener diode should be selected from among devices with a voltage of 5 ... 7.5 V and always in a metal case, for example, KS156A, KS168A, D808.

As a fuse FU 1, a piece of wire with a diameter of about 0.05 mm was used from the frame of a faulty microammeter. In the event of a burnout of the insert (for example, during a thunderstorm), the need to check the health of the zener diode VD 5, if necessary, replace it and only then turn on the signaling device with a new plug in the network.

HL LED 1 lights up immediately after the signaling device is connected to the network. To put the device into standby mode, just briefly press the button SB 1. After the dip is detected and the LED signal is noticed, you can press the button again to turn off the LED and return the device to standby mode.

Pankov E.

Perm

Stove gas burner burner

It is no secret that gas stoves should be used with caution. But sometimes, after removing the pan from the heat, we forget to turn off the gas burner. To get out of this situation, prompting about an oversight in time, can be a gas combustion signaling device, the diagram of which is shown in Fig. 5.

Fig.5

It is based on a multivibrator based on transistors of various structures ( VT4, VT 5), supplemented by an amplifying stage ( VT2, VT 3) with thermal sensor.

The role of the thermal sensor is performed by the transistor VT 1 placed above the gas stove. per transistor VT 1 no heat is active while there is a pot or kettle on the burner. One has only to remove them, as the heat from the combustion of gas rushes up and heats the transistor VT 1. This will cause a change in the resistance of the collector-emitter section of the transistor and will lead to an increase in the voltage across the resistor R1.

The change in the signal across the resistor is amplified by a two-stage transistor amplifier VT2 and VT 3. On the collector of the transistor VT 3 there will be a significant decrease in the voltage value to such a value that the sound generator on transistors will turn on VT4 and VT 5. At this moment, an alarm signal will sound from the electrodynamic head, indicating that the gas burner is turned on and is unattended.

The tone of the signal is selected by changing the capacitance of the capacitor C1. The signaling device in standby mode consumes a current of 0.2 ... 2 mA, depending on the position of the axis of the variable resistor R 1. When a signal appears, the current consumption increases to 10 mA.

A transistor from the MP39 ... MP42 series is selected for the sensor using an ohmmeter. Connect the negative probe of the ohmmeter to the collector, positive to the emitter and fix the resistance value: if it is more than 20 kOhm, then the transistor can be used as a sensor.

The signaling device, assembled from known good parts, is immediately ready for operation. The operation of the sensor is checked by closing the collector and emitter of the transistor VT 3. In this case, a sound should be heard, when opened, the sound will disappear. Next, the scale of the variable resistor is calibrated. The sensor is installed above the lit burner, the variable resistor is set to the middle position, the signaling device is turned on and the time of the signaling device is fixed on the scale. This operation is performed at different positions of the variable resistor slider. After grading the scale, the indicator is ready for practical use.

Pestrikov V.M.

"Ham Radio Encyclopedia"

"Cover the refrigerator" signaling device

A miniature open door signaling device can be made on the K176LA7 chip (Fig. 6).

Fig.6

On elements DD 1.3 and DD 1.4 an audio frequency tone generator was assembled. The tone of the sound depends on the capacitance of the capacitor C3 and the resistance of the resistor R 3. On elements DD 1.1 and DD 1.2, another generator is assembled, periodically turning on the tone generator.

The signaling device is controlled by miniature contacts or a gecko SA 1. If the door is open (which means that the contacts are open S 1) more than 30 s (time delay depends on the resistance of the resistor R 1 and the capacitance of capacitor C2), the generator will turn on on the elements DD 1.1 and DD 1.2, the tone generator starts working and in the capsule bf 1, intermittent beeps will sound. The frequency of repetition of signals depends on the capacitance of the capacitor C1 and the resistance of the resistor R 2 (it is selected when setting up the structure).

Nechaev I.

G. Kursk

Refrigerator open door alarm

Figure 7 shows the simplest diagram of the refrigerator door open signaling device. The design is made from an old Chinese-made alarm clock.

Fig.7

Here, instead of a bell switch, a conventional photodiode from the remote control systems of old domestic TVs is turned on. It is connected in the opposite direction, that is, like a photoresistor. In the dark, its resistance is high and the alarm does not sound. When the refrigerator door is opened, the interior light comes on.

The light from it hits the photodiode and the structure located in the refrigerator starts to sound.

Temperature change alarm

One of the problems of reliable operation of electronic structures is the protection of their most important elements from overheating. For this purpose, a device has been developed, shown in Fig. 8, signaling a change in the temperature regime of such elements.

Fig.8

Its basis is a sensor on a silicon diode KD102A ( VD one). When the temperature of the diode changes by one degree, the voltage falling at the diode terminals during forward bias changes by two millivolts. Moreover, it decreases as the temperature rises. In other words, the diode has a negative temperature coefficient of resistance.

The inverting terminal of the operational amplifier is connected to the anode of the diode. DA 1, and the reference voltage from the variable resistor engine is applied to the non-inverting output R 4, which determines the alarm threshold. When the voltage at the anode of the diode exceeds the voltage at the slider of the variable resistor, the signal at the output of the operational amplifier DA 1 is almost equal to zero. LED on HL 1 green. If the voltage at the anode becomes less than the reference voltage, a positive voltage will appear at the output of the amplifier, the LED will light up HL 2 red, warning about an increase in the temperature of the object near which (or on which) the temperature sensor is installed.

Since the operational amplifier has a large gain and is very sensitive to alternating electromagnetic fields, a capacitor C1 is installed in the feedback circuit of the operational amplifier to protect against them.

Creative workshop "Homemade"

Bobrovsky V.

Nartkala

Signaling device "Field flowers!"

A simple device, the diagram of which is shown in Fig. 9, will tell you when you need to water the plants, since when the soil dries out, a reminder signal will turn on.

Fig.9

The device reacts to the conductivity of the soil, which is highly dependent on its moisture content: the drier the soil, the worse its conductivity. Two electrodes are immersed in the soil in a flower pot and connected to the device by conductors. While the soil is damp, resistance R n is small, therefore, the voltage at the base of the transistor is low and it is closed. There is no sound signal. As the soil dries out, the resistance R n increases and at some point in time becomes such that the transistor T1 opens and the supply voltage is applied to the sound generator. There is a low, but quite distinct sound signal.

The desired tone of the signal is regulated by the selection of the capacitance of the capacitor C1. With a variable resistor R 2 set the device response threshold. At the same time, an interesting feature should be noted: as the soil dries out, its resistance gradually increases and therefore the transistor T1 gradually begins to open slightly. A soft tone is heard, the volume of which increases over time.

Electrodes 1 and 2 must be made of nichrome wire with a diameter of 0.5-1 mm. You can also use narrow strips of stainless steel.

Acoustic signaling of the arrival of guests

The simple electronic circuit shown in Fig. 10 has a high input sensitivity and is used to warn of the approach of any living object (for example, a person) to the E1 sensor.

Fig.10

The circuit is based on two elements of the K561TL1 chip ( DD 1) connected as inverters.

Foreign analogue K561TL1 - CD 4093B.

In the initial state after turning on the power at the input of the element DD 1.1, there is an indeterminate state close to a low logic level. At the exit DD 1.1 - high level, output DD 1.2 is again low. Transistor VT 1, acting as a current amplifier, is closed. Piezoelectric capsule HA1 (with internal AF generator) is not active. When touching a bare part of the human body (for example, a finger) to conclusions 1 and 2 DD 1.1, the alternating voltage induced in the human body switches elements DD 1.1, DD 1.2 to the opposite state, and they remain in it until the next effect of the pickup voltage on the input of the element DD 1.1. With the value of C1 indicated on the diagram, this electronic assembly works as a bistable trigger.

A high voltage level appears at pin 4, as a result of this transistor VT 1 opens and the capsule HA1 sounds.

By selecting the capacitance of the capacitor C1, you can change the mode of operation of the microcircuit elements. So, when the capacitance C1 decreases to 82 ... 120 pF, the node works differently. Now the beep sounds only while the input DD 1.1 affects interference - human touch.

Based on this experiment, a constant resistor is connected to the input R 1 with a resistance of 10MΩ (depending on the length of the wire to the sensor and the external installation conditions of the node). Consistently with R 1 (in that order) connect a shielded wire (cable RK-50, RK-75, shielded wire for rewriting AF signals - all types are suitable) 1 ... 1.5 m long, the shield is connected to a common wire.

The invention relates to refrigeration engineering. A refrigerator with a door open sensor has a non-contact controlled switch and a casing surrounding the switch, which is equipped with fasteners for releasably fixing the casing in the hole, with plug contacts available on one side of the casing for connecting the switch to the electrical circuit. A contact socket with mating contacts for the plug contacts of the switch is mounted on the wall of the refrigerator. The switch is located on the board and there are plug contacts on one edge of the board. The switch is a magnetic switch, in particular a reed switch. The invention is aimed at creating a door opening sensor that is insensitive to moisture, with the possibility of installing it on the refrigerator body and replacing it. 11 w.p. f-ly, 7 ill.

State of the art

Refrigerators are usually equipped with a switch to detect the open or closed position of its door or doors.

A well-known design is a mechanically operated electric switch mounted on the refrigerator body near the door and interacting with a cam on the door. Such a switch may, for example, be mounted in a metal or plastic front panel on the front of the refrigerator just above or just below the door and actuated through a hole in the front panel. The switch drive is carried out by an element rigidly connected to the door. With such a system, the circuit breaker can usually be dismantled without destruction in case of repair, and a new circuit breaker can be installed in the same place.

The disadvantage of this solution is the mechanical vulnerability of the switch, in particular its movable, door-operated pusher. This latter in particular may be damaged during transportation of such a refrigerator. If the door is not correctly positioned, for example, if the door stop was changed when the refrigerator was installed, or if the door is heavily loaded, it may happen that the mutual overlap of the pusher and the door switching element is not complete, and the switch does not work.

Another disadvantage may arise if the switch is installed under the refrigerator and/or freezer, from where water can escape during the defrosting cycle. The need for a movable pusher determines the presence of a gap in the circuit breaker housing, through which water can penetrate inside the circuit breaker and get on live parts.

A known way to get rid of the problems associated with inaccurate positioning of the door and, in particular, with the penetration of moisture, is the use of a magnetic switch in the door open sensor, in particular a reed switch in combination with a magnet fixed to the door. Such a switch can be, for example, mounted by means of foam in the body of the refrigerator close to the door. The disadvantage of this solution is that, in the event of a malfunction, such a switch cannot be replaced in a non-destructive manner.

To overcome the disadvantage of not having access to the magnetic switch, it was proposed to install it on the electronic board, which contains the control electronics of the refrigerator, and which is housed in a plastic case attached to the front of the refrigerator. When repairing, you can remove the plastic case, unsolder the faulty magnetic switch and solder a new one.

In an advanced version, the magnetic switch is not soldered to the electronics board, but to an auxiliary board, which is equipped with wiring and/or a plug for connection to the electronics board. The advantage of this solution is that the magnetic switch inside the plastic housing can be installed in a different place than the electronics board. However, the disadvantage remains that in this embodiment, the switch can only be placed inside the housing cavity, in which the electronics board is also located. Therefore, this switch can only detect the opening and closing of a door directly above or below the cabinet. In particular, in a multi-door refrigerator, this known solution is not applicable to a door that is not adjacent to the electronics board housing.

Disclosure of invention

The objective of the invention is to create a moisture-insensitive door sensor that can be installed on the refrigerator body in almost any place close to the door and can be easily replaced.

This problem is solved with the help of a door opening sensor having the characteristics of paragraph 1 of the claims.

Since this switch has its own housing and plug-in design, it can be installed anywhere in the refrigerator body, where a socket for installing a switch can be provided.

The switch, preferably a reed switch, is advantageously mounted on a board placed in the casing, one edge of which is intended to accommodate the plug contacts required for connection to the switch.

Preferably, these plug contacts are made in the form of current-carrying tracks on the edge of the board.

The shroud can be open at the back so that the board can be easily pushed into the shroud from the back. The possibility of moisture penetrating through the open back side cannot be assumed, since a suitable seal is made between the front part of the casing and the surrounding edge of the opening. This sealing can be facilitated in particular by a collar surrounding the casing, which, in the assembled state of the door opening sensor, must lie against the front side of the wall on which it is fastened. Between the belt and this front side, a sealing element can be clamped.

In order to facilitate the placement of the door sensor in the hole, the edge of the board facing the front side of the casing is rigidly fixed, for example by means of a clamp, in the direction perpendicular to the surface of the board, and the edge of the board, on which the plug contacts are located, is free to move in the direction perpendicular to the surface of the board. to the board surface. This rigid clamping on one side and freedom of movement on the other side can in particular be achieved by means of board guide grooves converging towards the front side of the casing inside the casing. This freedom of movement makes it possible to compensate for possible inaccuracies in the relative position of the hole and the contacts located in it, intended for connection with the plug contacts of the switch.

To facilitate the installation of the casing on the refrigerator, a contact socket can be additionally installed on the inside of the hole in the wall of the refrigerator, into which the casing is inserted and in which there are mating contacts for the plug contacts of the switch.

These contacts can, in particular, be located in a contact element held in the socket of the contact socket between the shoulder and the latch.

Brief list of drawing figures

Other features and advantages of the present invention follow from the following description of examples of implementation with reference to the figures. The figures represent:

Fig. 1 is a perspective view of a refrigerator according to the present invention;

Fig 2 and 3 - sections of the door opening sensor according to the invention in two mutually perpendicular planes;

Fig.4 and 5 is a section of the wall of the refrigerator with a contact socket installed on this wall in cut planes similar to Figs. 2 and 3; and

Fig.6 and 7 - sections of the door opening sensor, mounted in the wall in the same cut planes.

Implementation of the invention

Figure 1 shows a refrigerator in perspective projection, equipped with sensors for opening the door in accordance with this invention. The refrigerator has two doors 50, 51 covering, for example, a normal refrigerator compartment and a refrigerator compartment at a temperature of about 0°C or a normal refrigerator compartment and a freezer compartment 52, 53. Under each of the compartments 52, 53, a sensor 54 is located on the front side of the refrigerator body. door opening sensor, facing the lower edge of the door 50, 51. The door opening sensors 54 are located on the front side of the refrigerator body approximately in the middle, so that their sensitivity does not depend on which side of the body the doors 50, 51 are opened to.

The magnet acting on the door opening sensor 54 is mounted in the door 50 or 51 opposite the door opening sensor 54 . The door sensors 54 can, of course, be installed in other places on the front side of the refrigerator body, in particular also in holes made in the internal containers of the refrigerator.

Figure 2 shows a section of the door opening sensor 54 in a plane horizontal relative to the location of the door opening sensor 54 shown in figure 1

Figure 3 shows a section of the same sensor in a vertical plane. The secant plane of Fig. 3 is indicated in Fig. 2 III-III, and the secant plane of Fig. 2 is indicated in Fig. 3 II-II.

The door opening sensor 54 consists of three main parts: reed switch 1, board 2, to which reed switch 1 is soldered, and casing 3, in which board 2 with reed switch 1 is located.

The body 17 of the one-piece casing 3 made of plastic has basically the shape of a rectangular parallelepiped, open on the rear side and surrounded by a bead 8 on the four sides. side to the closed front side of the housing 17 grooves 19 serving as guides and holders for the board 2. Near the front side, the board 2 is clamped in these grooves 19 almost motionless, and near the rear side it has some freedom of movement.

From the open rear side, the case 17 is continued by two flexible brackets 20 emerging from the ribs between one of the wide sides 21 and two narrow sides 18. At the free ends of the brackets, there are clamps 24. When the board 2 is inserted into the grooves 19, the brackets 20 can slide outward, and their length is chosen in accordance with the length of the board 2, so that when the front edge 23 of the board 2 reaches the narrow front end of the slots 19, the latches 24 engage the rear edge 22, thus fixing the board 2 in the casing 3.

The shape of the latches 24 engaging behind the trailing edge 22 of the board 2 is chosen taking into account the freedom of movement of the board in the back of the slots 19, so that in any position that the board 2 can take, the adhesion between the latches 24 and the trailing edge 22 is maintained, and the brackets 20 this is not bent.

The reed switch 1 is located on the surface of the board 2 from the side opposite to the brackets 20. The current-carrying tracks 6 stretch along the surface of the board 2 from the leads of the reed switch 1 to the pads 7 on the trailing edge 22 of the board 2. The pads 7 are wider than the current-carrying tracks 6, they serve as plug contacts for connections with the electrical contacts of the contact socket shown in figures 4 and 5.

On the outer sides of the narrow side walls 18 there are two shackles 14 compressible in the plane of FIG.

Figures 4 and 5 show sections in two planes of the contact socket 32 ​​installed in the hole 30 of the wall 4 of the refrigerator and designed to insert the casing 3 into it and form contact with the reed switch 1.

The plastic-molded contact socket 32 ​​basically consists of two hollow sections, approximately box-shaped, a plug section 33 and a wiring section 34. The plug section 33 has an open side facing the wall 4, surrounded around the perimeter by a flange 35. The flange 35 is glued to the inside of the wall. 4. The cavity of the plug section 33 is higher and wider than the hole 30 behind which it is installed.

The wide side walls 36 of the plug section 33, one of which is shown in plan in FIG. 4, have a number of ribs 15 and 16 protruding into the plug section 33 cavity. is chosen such that they hold or even slightly clamp the wide side walls 21 of the casing 3 inserted into the plug section 33 without play. between each other, the rear edge of the board 2 and direct it to the receiving slot 37 of the contact element 5. As can be seen, for example, in Fig.5, the contact element 5 is held in the sleeve 40, which is formed in the partition 39 separating the sections 33, 34. To fix the contact element 5 in the direction of insertion of the casing 3 are, firstly, two locks 41, which are connected by flexible tabs 42 with two short ribs 15 and when the contact element 5 is inserted into the sleeve 40, they move apart to the side s. Secondly, a shoulder 43 formed in the sleeve 40 restricts the movement of the contact element 5 in the direction of the opening 30 so that the contact element cannot be pulled out together with the board 2 in case the door sensor needs to be replaced.

Two wires 44 for connection to the reed switch 1 extend from the contact element 5 through the wire entry section 34 to a (not shown) inlet where they exit the wire entry section 34 into the insulating foam layer 13 surrounding the contact socket 32 ​​from the outside. The input is formed by one or two cutouts in the side wall of the wire supply section 34, which are adjacent to the cover 31 separated from the rest of the wire supply section 34.

The installation of the door opening sensor according to the invention begins with the fact that the flange 35 of the contact socket 32 ​​is glued to the inner side of the wall 4, surrounding the opening 30. By this time, wires can already be attached to the contact element 5, it can be fixed in the sleeve 40, and a cover 31 is installed on the wire supply section 34; however, the installation of the contact element 5 and the cover 31 can also be carried out after the contact socket 32 ​​is installed on the wall 4.

The cover 31 protects the wire supply area from the penetration of foam 13 when it covers the door opening sensor.

After mounting the contact socket 32 ​​on the wall 4, the casing 3 can be inserted through the hole 30 into the plug section 33.

Figures 6 and 7 show in sections in two mutually perpendicular planes II-II and III-III the door opening sensor mounted on the wall 4 of the refrigerator. The shackles 14, compressed during insertion through the hole 30 of the casing 3, restored their original configuration, and the casing 3 was fixed to the wall 4 by means of a clamp between the shoulder 8 and the shackles 14.

Figure 6 shows a sealing ring 9 clamped between the shoulder 8 and the wall 4; it can optionally be provided if there is a significant risk of moisture penetrating into the plug section 33, for example if the wall section 4 in which the opening 30 is located can be flooded with melt water formed inside the refrigerator.

To replace the door opening sensor in the event of a malfunction, it is enough to take, for example, with pliers the front part of the casing 3 protruding from the wall 4 and pull the casing out of the hole 30. Then, bending the brackets 20, you need to pull the board 2 out of the casing 3 and replace it. After that, it remains only to reinsert the casing 3 into the hole 30.

1. Refrigerator with a door opening sensor having a non-contact controlled switch (1) and an ambient switch (1), a casing (3), which is equipped with fasteners (14, 8) for detachable fastening of the casing in the hole (30), and on one side housing (3), plug contacts are available for connecting the switch (1) to the electrical circuit, characterized in that a contact socket (32) with mating contacts for the plug contacts of the switch (1) is mounted on the wall (4) of the refrigerator.

2. Refrigerator according to claim 1, characterized in that the switch (1) is a magnetic switch, in particular a reed switch.

3. Refrigerator according to claim 1, characterized in that the switch (1) is located on the board (2) and that there are plug contacts on one edge of the board (2).

4. Refrigerator according to claim 3, characterized in that the casing (3) is open on the rear side to allow the board (2) to be pushed through the open rear side into the casing (3).

5. Refrigerator according to claim 4, characterized in that the board (2) on its edge (23), facing the front side of the casing (3), is fixed in a direction perpendicular to its surface, and on the edge (22), on which the plug contacts are located, has freedom of movement in a direction perpendicular to its surface.

6. Refrigerator according to claim 5, characterized in that inside the casing (3) there are grooves (19) tapering towards the front side of the casing, which serve as guides for the board (2).

7. Refrigerator according to one of claims 3 to 6, characterized in that the plug contacts are pads (7) located on the edge (22) of the board (2).

8. Refrigerator according to any one of claims 1 to 6, characterized in that the casing (3) has a shoulder (8) located along its perimeter.

9. Refrigerator according to claim 8, characterized in that the contact element (5) containing the return contacts is held in the sleeve (40) of the contact socket (32) between the shoulder (43) and the latches (41).

10. Refrigerator according to claim 8, characterized in that the bead (8) rests against the outer side of the wall (4).

11. Refrigerator according to claim 10, characterized in that a sealing element (9) is clamped between the shoulder (8) and the outer side of the wall (4).

12. Refrigerator according to claim 11, characterized in that the casing (3) of the door opening sensor (54) has four side walls (18, 21), two opposite side walls (21) are pressed between the guides (16) of the contact socket (32) , and on the other two opposite side walls (18) there are locking elements (14) that provide detachable fastening.

T.A. Babu

An open refrigerator door can significantly increase your energy bill. This simple device will start beeping if you leave the refrigerator door open for more than 20 seconds. When the door is open, the light comes on and the 4060B counter starts counting down. With a delay of 20 seconds, the piezo emitter begins to emit periodic sound signals, which continue, again, for 20 seconds. Then the signal is interrupted for 20 seconds. This cycle is repeated as long as the refrigerator door remains open.

Usually, either a step-down transformer or a quenching capacitor is required to obtain a low DC voltage from the mains voltage. The highlight of this project is that we do not need either one or the other. When the refrigerator door is opened, power is supplied to the light bulb through the diodes D1 ... D4 of the bridge rectifier, and through the zener diode Z1 (see figure). The voltage drop across the zener diode is smoothed out by the filter capacitor C1. This voltage is sufficient to power the rest of the circuit.

To connect the circuit, it is necessary to cut the wire going to the refrigerator light bulb as shown in the figure, and connect the circuit (shaded part of the figure) at points A and B. You can place the circuit in the compressor compartment. There are more than enough places. When the door is closed, the light is off and the circuit draws no power.

The circuit is powered directly from the mains. Therefore, caution and some idea of ​​​​the device of the refrigerator would not be superfluous for you at all.

• It seems to me that now this is not relevant, all modern refrigerators already have this signaling device.
• It is not necessary to use this alarm in the refrigerator. Have you turned off the light in the bathroom, closet, hallway, etc.? Valuable solution for the formation of supply voltage. The weak point in the circuit is the protection of the diodes when the light bulb burns out, at this moment, there is often a surge of current comparable to a short circuit "knocking out the circuit breakers.
• Tell me how to apply to the bathroom? What changes to make?
• Yes, yes, I agree with this, I forgot to indicate in the first post. But I am more satisfied with options with galvanic isolation from the network, or battery options for such devices.
• When entering the bathroom, I think you won’t forget to close the door, otherwise you can accidentally find your photos on the internet :) But when you leave, you can do without a time relay. The solution couldn't be easier. If you forgot to close the door and the light is off, the squeaker will work. There will be no false positives, because first the door must be closed, and then the hand is freed to turn off the light.
• I can't agree that every refrigerator has an alarm. I don't have one, Atlant. I personally would be very annoyed by this squeak. I don’t like extraneous noises, the refrigerator is buzzing so if it squeaked it would be too much.
• I have had a refrigerator for 2 years, and I only heard the squeaker when I wiped the shelves. He does not squeak right away, but after a while only in an emergency, when they forgot to close it.
• This scheme is only suitable if the refrigerator has a light bulb. But there is a light bulb only in the large compartment, and in the freezer, which is at the bottom of the refrigerator, there is no light bulb. Unfortunately, it is the freezer that my family sometimes does not completely close. At least put the spring, as on the doors :)
• you can use a sound signaling device to fill the bathtub with water that has filled to a certain level .. or buckets for washing floors. In my opinion, you can find simple diagrams on the Internet. :)
• The refrigerator should simply be installed slightly tilted back. And that's it!

This article will present a simple signaling device that notifies you that the refrigerator door is not closed, or not completely closed (as is often the case).

Here is the signaling circuit:

This signaling device gives an audible and, if desired, a light notification of an open door.

Design:

Parts used in the device:

Rel1 - any reed relay, for example, RES42.

Rel2 - RES10.

Rel3 - any, for example, RES43.

C1 - C6 - time delay modules, blocks of capacitors connected in parallel.

C7 - 0.1 uF.

S1 - any switch with 5 positions.

S3 - any latching switch, for example, from a computer PSU.

Tr1 is a transformer for 7 - 12 volts, but it is advisable to choose a transformer with the output voltage that is needed for the normal operation of the relay.

VDS1 - any diode bridge.

Horn1 - alert signaling, bell.

VD3 - better more powerful, for example, KD203.

La2 - 220 volt incandescent lamp.

C8 - a capacitor for a voltage of at least 250 volts.

R3, R4 - resistors, with a power of at least 4 watts.

VD4 - thyristor KU202N, but TS112 is also possible.

As Horn1, you can use a call from rotary phones, but then it will have to be connected through a relay to the network. But you can assemble an alarm like this:

Then the conclusions "To the circuit under test" must be connected to relay3.

photorelay

A photorelay for our signaling device is needed in order to know whether the door is open or not, because. when the door is opened, the lamp comes on. The photo relay should be placed inside so that the light from it hits the photo sensor well. There are a lot of different photo relay circuits. The type of photo relay is unimportant.

They figured out the relay, but I had a problem - the lamp in the refrigerators turns off even before the door is completely closed, and this is how it often happens. Yes, and there are not quite enough parts on the photo relay. And I decided to put an opening button in front of the door.

But there were no suitable sizes. And then I decided to assemble such a button according to the following scheme:

If the device is placed next to the refrigerator, for example, on a table, then only one wire can be used to connect it to the button. But this is possible only under one condition: if the refrigerator is iron (in the sense it conducts current). To do this, connect the wire to the contact of the button, and connect its other contact to the refrigerator body. From the other end, where the device is, connect the desired contact to the refrigerator body too. Check again with a multimeter, ohmmeter or a simple sound generator that there is contact between the button and the device. Button - preferably as small as possible, but better in general, a homemade button made from pieces of tin or foil. This is how it should be done:

And here's the best way to make a button:

Then the cold from the refrigerator will not come out.

Switch S1 selects the alarm response time.

If desired, the strobe on the LA2 lamp can be removed, then the relay can be replaced with a smaller one.

It happens that the door of the refrigerator, due to inattention, remains “open, and warm air penetrates into it. As a result, the temperature inside the refrigerator rises, the walls of the refrigerator chamber quickly become overgrown with a fur coat, the refrigerator electric motor turns on more and more often, which leads to increased energy consumption.

The signaling device avoids unnecessary losses. It is assembled (Fig. 64, a) “on one microcircuit and consists of two generators, one of which is tone, assembled on elements DD1.3, DD1.4, switched on by the second generator on elements DD1.1, DD1.2. The operation of the signaling device is controlled by the SA1 contacts installed on the refrigerator body, opposite its door.

In standby mode, when the refrigerator door is tightly closed, the contacts are closed, none of the generators works. In this mode, the signaling device consumes a current determined by the resistance of the resistor R1 and the leakage current of the microcircuit.

If the refrigerator door is open or not tightly closed for a long time, the capacitor C2 is charged through the resistor R1, and when the voltage on it reaches a high level, the generator will start working on the elements DD1.1, DD1.2. The pulse repetition rate is approximately 1 Hz. At the same frequency, the tone generator is turned on and off. Thus, if the refrigerator door is open for a certain time, then an intermittent sound signal will be heard in the telephone BP1.

The duration of the delay in the sound signal depends on the resistance of the resistor R1 and the capacitance of the capacitor C2. When the door is closed, the capacitor quickly discharges through the closed contacts SA1 and the signaling device goes into standby mode. If the door is opened / for a long time, for example, to defrost the refrigerator, then for this time the signaling device power supply is turned off by a special switch or simply by disconnecting the GB1 battery.

Rice. Fig. 64. Signaling device circuit (a), SA1 contact design (b) and signaling device circuit board (c)

The fixed part of the SA1 node is a piece of foil textolite with a thickness of not more than 0.5 mm (Fig. 64, b) with two contact pads. The textolite is glued to the refrigerator body opposite the rubber door seal. The second part of the assembly is a smaller piece of foil glued to the rubber seal opposite the first part. With the door closed, this segment should close the contact pads.

The BF1 phone must be high-resistance, the power source can be a Krona, Corundum battery or two 3336, Rubin batteries connected in series. The circuit board is shown in fig. 64, in.

The delay time of the signaling device is set by selecting the capacitance of the capacitor C2, the required tone of the signal - by the capacitor C3, and the frequency of the signal - by selecting the capacitance of the capacitor C1.

References: I. A. Nechaev, Mass Radio Library (MRB), Issue 1172, 1992.