Schemes of the simplest combination locks for a summer residence. How to make an electronic combination lock

Electronic combination lock

This lock is easy to make and install. At the same time, it allows the use of a four-digit code and limits the time it takes to dial the latter. Electronic part The lock is made on K561 series CMOS chips. The schematic diagram of the device is shown in Fig. 1.
Rice. 1. Schematic diagram of an electronic lock
The device consists of four RS triggers (two K561TM2 microcircuits) DD1. 1, DD1. 2, DD2. 1, DD2. 2. The dial buttons are located on the outside of the door. Before entering the code, you must press the SB11 “Reset” button. In this case, capacitor C1 quickly discharges, and after releasing the button, it begins to slowly charge from the + 9 V power source through resistor R3. Until the voltage on capacitor C1 reaches a value of + 4.5 V or more, at the S input of trigger DD1. 1 there is a zero potential, which allows the operation of the first RS flip-flop on element D1. 1.
When you press the SB1 button (the first digit of the code), the trigger switches and at its direct output the positive potential changes to zero. This potential allows the next trigger to operate on element DD1. 2.
After pressing the SB2 button (second digit of the code), the trigger is on element DD1. 2 switches and a zero potential appears at its inverse output, thereby allowing the operation of the next RS flip-flop on element DD2. 2. Next, press the buttons SB3 (third digit of the code) and SB4 (fourth digit of the code) sequentially. Finally, the last RS trigger on element DD2 is triggered. 1, a zero potential appears at its inverse output, which leads to the closing of transistor VT1 and, as a consequence, to the opening of transistor VT2, which turns on an actuator, such as a relay or electromagnet.
Direct output of RS trigger DD2. 1 cannot be used to turn on the actuator. This is due to the fact that in this case the actuator is activated even when only one button SB4 is pressed, i.e., without dialing the first three digits, and this is unacceptable.
The time for dialing code digits is limited by the charging time of capacitor C1 and depends on its capacitance and the resistance of resistor R3. At the ratings shown in Fig. 1, the charging time is approximately 15 s. If the code is not entered during this time, then all RS triggers will return to their original state and the dialing will have to be repeated. If at least one incorrect digit is entered while dialing the code (buttons SB5-SB10), then all RS triggers will also return to their original state.
The number of digits in the code can be increased if several more microcircuits are connected in series. But, as practice shows, four digits provide sufficient system reliability.
The printed circuit board of the device is made of single-sided foil glass PCB measuring 65x40 mm. Drawing printed circuit board shown in Fig. 2. The RES-49 relay was used as an actuator. The placement of elements on the device board is shown in Fig. 3. Microcircuits DD1, DD2 of the K561TM2 series can be replaced without changing the design of the printed circuit board with K176TM2 microcircuits. Resistors R1 -R7 - type MLT-0, 125 or similar. Capacitor C1 must be selected with the lowest possible leakage current. The dialing time is set experimentally by selecting the value of capacitor C1. You can use any buttons, including from telephone set(except SB11).

In this article we will talk about the circuit and installation of an electronic combination lock.

“If you have one key in your pocket, that means your key to the apartment, and you are the big boss! If you have two keys on a ring, then you have an office, and you are an office worker! If you have three or more keys, then you are the warehouse manager!” Folk wisdom.

Carrying a large bunch of lock keys in your pocket is a big inconvenience. This is especially true not in winter, but in summer. In that season when a person has less clothes, which means fewer pockets. And if the bunch of keys is large, then its weight can rub holes in your pockets. To prevent pockets from rubbing, various key holders are used, but key holders increase the size of the key ring, which not only causes inconvenience. Protruding pockets look unsightly. Women are luckier in this regard than men, because they have “oversized” handbags. What can't you find there? To unload their pockets, men use purses. But the purse also presents some inconvenience - one hand is constantly occupied with carrying it.

What to do if there are a lot of people working in the office space? Go to the key keeper and do large number duplicates! There is another way: Install on front door code lock.

There are a large number of mechanical combination locks sold in stores, but they have disadvantages. Push-button locks have a weak degree of security - the code is easy to select.

Locks with wheels are inconvenient to use - first you need to set all the wheels to the required numbers, open the lock, and then turn the wheels again to “knock down” the code combination. The most convenient to use is an electronic combination lock.

There are many on the Internet different schemes combination locks, but after delving into global network, I discovered that all combination lock circuits made on one or two microcircuits have poor security against hacking, which, provided the keypad is easily opened, can be opened using an ordinary machine, multimeter, or logic probe. Of course you can collect the simplest scheme, but it must come with a “cast iron” keypad so that the wires cannot be reached. I offer you a diagram of an electronic combination lock that does not need a “crackable only with an angle grinder” button panel. If they break anything, it's just the panel. But a cast iron panel can also be hit once with a heavy object, rendering it inoperable. During five years of operation, the proposed combination lock showed high reliability - it never broke and was highly burglar-resistant.

You can see the view of the combination lock from the outside of the door in the photo - it is only a light button panel. View of a combination lock with inside the door is shown below.

The proposed electronic combination lock is made on two CMOS chips 561LA7 and one 561LE5, has low power consumption from the network - about 2 milliamps on the secondary winding of the transformer in standby mode. When powered by battery, current consumption is measured in units of microamps. Thus, the combination lock is powered by industrial network, and if it disappears, from a 12-volt battery. If there is an industrial network of 220 volts, the battery is recharged, and in the absence of an industrial network, it serves as the power source for the lock.

The schematic diagram of an electronic combination lock is shown in the figure.

IN original condition the entire circuit, except for the power supplies, is de-energized. The unit, assembled on transistors VT1-VT3, is designed to supply power to the electronic code dialing unit for the limited time required to dial the code (about 10...15 seconds). Power is supplied by pressing the “,” button. This button is not a code button. Limiting the power supply time is designed to ensure that the lock's electronic circuitry does not consume power during standby mode. Therefore, if you keep this button pressed, then the power on the circuit will be constantly present, and will disappear 15 seconds after releasing the “,” button.

The SA1 code dial is a button panel, located outside the lock and connected to the lock circuit using twelve thin stranded conductors.

The SR1 code setting panel is designed to set the lock code. The panel used for setting the fixed frequencies of the R-140 radio station, or the R-155 radio receiver, where special plugs are used. Perhaps, instead of the dial pad, use other switching methods.

After setting a certain code, the SR1 code installation panel is closed with a special lid and sealed with a mastic seal. This way, when leaving the premises, you can check that no one snooped on your code. Otherwise, once you open the lid, you can quickly change it and reseal the lid. The circuit diagram shows the setting of the lock code “3052”. In the photo of the panel it is “5491”.

As you understand, the dialing code is four-digit (not counting the power button “,”). The code is dialed by sequentially pressing the buttons. If the buttons are not pressed in the prescribed sequence, the lock will not open. It is possible to press all simultaneously four buttons code, but in any case, the actuator will operate for a time limited by the charging time of capacitor C7, equal to 1 second. Capacitors C5-C6 limit the time required to dial the code. If the code is not entered within 10 seconds, then the actuator will not work and the code must be entered again.

The circuit assembled on the elements of the D3 microcircuit is designed to prevent unauthorized selection of the lock code. When you press any of the six “wrong” buttons, the one-shot device D3.2-D3.3 blocks the code set and the actuator for 15 seconds. This time is determined by the ratings of elements C9 and R17 and the time of power supply from the power supply. After this, to open the lock you must wait at least 15 seconds and enter the code correctly. If the “wrong” button is pressed again, the lock will be locked again for 15 seconds. If, during blocking, without waiting 15 seconds, the attacker supplies power to the lock with the “,” button, then the blocking will last for another 15 seconds. The self-locking unit greatly complicates attempts to guess the code.

In our case, on the typesetting field SR1 schematic diagram the “wrong” buttons are installed – 1, 4, 6, 7, 8 and 9. In the case of a self-locking lock, there are no audible or visible signs, so the attacker does not know about it, which does not allow him to identify the “wrong” buttons. It is also impossible to determine that the combination lock has become self-locking by the presence or absence of voltage on the contacts of the opened dial pad using any electronic devices.

When the correct code is dialed, the executive contact group of relay P1 supplies power to the lock actuator (electromagnet or motor). The power supply time is determined by capacitance C7 and is approximately 1 second. To adjust the power supply time to the executive relay manually (by the duration of pressing the last button established code), but no more than 2 seconds, you need to disconnect resistor R12 from pin 4 of element D2.4 and connect it to the common wire of the circuit.

About the elements of an electronic lock circuit

561LA7 microcircuits are interchangeable with 176LA7, or an imported analog CD4011. The 561LE5 microcircuit is replaceable with 176LE5, or an imported analog CD4001. Transistors VT1-VT3 - type KT361, or KT3107 with any letter. Transistor VT4 - type KT315, or KT3105 with any letter. Transistor VT5 - type KT815 with any letter.

The secondary winding of transformer T1 is designed for 12 volts. Transformer T1 is selected with sufficient power to ensure operation of the actuator; any rectifier diodes VD3-VD7 must also provide sufficient load current for the actuator. Diodes VD8-VD20 - any low-power pulsed ones. As a rechargeable battery, it is optimal to use a small-sized alkaline battery used in power sources uninterruptible power supply. The entire circuit, except for the digital keypad, the actuator, the battery and the power transformer, is housed in a plastic case measuring 10x14 cm.

The combination lock can be used without a battery if it is used as part of a lock that can also be opened with a key. That's exactly what I did. The key to one of our working premises is in the janitor's tube. I and my colleagues don’t have a key on their keychain. We open this room with a code, but if the light goes out, we take the key from the tube. To avoid running to the watchman in the absence of light after opening the room, the safe also contains a backup key.

As an actuator, I used a drive for unlocking and locking car door locks, hooking it on a chain to the flag of an ordinary rim lock, which “can” slam. This lock, or a similar one, is sold at any hardware store, and the drive can be purchased at any automobile store. The housing of the electronic circuit of the lock is located on the inside of the door, directly next to the actuator.

The SA1 code dialer is made from the keys of an old domestic calculator, is decoratively placed in a case made from a soap dish. It is brought outside the lock from the outside of the door and connected to electronic circuit in such a way that eliminates the possibility of selecting the code by “electronic scanning”, or hacking using measuring equipment. This is explained by the fact that no matter what state the lock is in, all its contacts have the same potential. No attempts to dial or close contacts in search of a code lead to anything. The circuit of the presented combination lock, like any other electronic locks, can be damaged by high voltage to the contacts of the opened keypad, but the lock still will not open.

Unfortunately, I cannot offer you a printed circuit board, because I made the castle ten years ago.

A rim lock, used in conjunction with an electronic combination lock, can be easily opened using a flat object inserted between the door and the jamb - a knife or a metal ruler. Therefore, when installing such a lock, provide conditions under which this will be impossible - the door frame and the door itself must be strong, and the gap must be closed with a recess that prevents access to the lock tongue.

Various electronic locks are now very popular, with electronic keys in the form of a “tablet” or “flash drive”. The key in them is a storage device in which a certain digital code. And the basis of the lock is a microcomputer, which reads and analyzes this code.

Two schemes of the simplest combination locks

I will not argue about the advantages and disadvantages of such locks; I simply bring to the attention of readers my development of a similar device operating on an analog principle. The essence of the matter is that in my lock the key is a zener diode for a certain stabilization voltage. If the zener diode in the key matches the stabilization voltage with the zener diode in the lock, the door opens. Moreover, outwardly everything looks as if it is a digital lock with a digital key. Of course, the number of “code combinations” of my lock is disproportionately less than a digital one, but... who knows that you need to select a zener diode?

I can imagine the hysteria of an “advanced” thief trying to guess the digital code to my lock. The diagram of the first version of the lock is shown in. The key is connector X1.1, which is connected to the mating connector X1.2. Ideally, you need to use the housing from the tablet key, such as iButton, and the corresponding connector for connecting it. But you can make any imitation, or use any two-pin connector pair, for example, from audio equipment. The key contains a zener diode, in in this case, at 8.2V and a 1N4148 diode connected in series with it.

When connected to connector X1.2, they form a stabilized source with resistor R1 constant voltage, equal to the sum of the zener diode voltage and the forward voltage of the diode. A two-threshold comparator is made on the comparators of the A1 LM339 chip. The reference voltage at its inputs is set by a circuit of resistor R2, two diodes VD4, VD5 and a zener diode, the same as in the switch.

When you connect your own key, a voltage is established on pins 4 and 7 of A1, which is greater than the voltage on the pin by the amount of forward voltage on the 1N4148 diode. 6 A1.2 and the same amount less voltage at the pin. 5 A1.1. Thus, the voltage at pins 4 and 7 of A1 connected together is between the voltages at pins 6 and 5. As a result, the voltage at the direct input of A1.1 will be less than at the inverse input, and at the output, unity. Exactly the same on A1.2, the output is one. The key on transistor VT1 opens and supplies current to relay K1.

Analog electronic combination lock

If the zener diode in the key is not at the same voltage as in the lock, then at least one of the comparators will be at zero at the output, and the voltage at the base of VT1 will not be enough to open it. The peculiarity of the LM339 microcircuit is that its outputs are made according to the circuits public keys, so they can be connected together, but they must be pulled up to the power positive with a resistor (R3). Of course, the zener diodes do not have to be 8.2V, they can be for any voltage from zero to 10V, but they must be the same. Capacitor C1 serves to slow down the response to the correct voltage, so that accidental opening does not occur if pulses or some kind of alternating voltage. So to speak, protection from accidents.

The diagram of a more complex lock is shown in Figure 2. A key in the form of a flash drive is used here. It is very similar to a flash drive, it has the same USB connector, but instead of a memory chip inside there are only two zener diodes and two diodes. Now the “secrecy” of the castle is twice as great. And all comparators of the LM339 chip are used. There are two zener diodes in the key, they can be the same, they can be different, but it is important that VD2 is the same as VD3, and VD7 is the same as VD11. Relay K1 type KUTS1M, from an old Soviet TV.

This relay has a high-resistance 12V winding, and two closing contact pairs, for a current of up to 2A each at a voltage of 220V. But you can choose an imported analogue, the winding should have a voltage of 12V and a current of no more than 30mA. No setup required. It is very important that all the diodes are the same, and the zener diodes in the key are exactly the same as in the lock, and from the same batch.

Practical combination locks are in greatest demand today. After the first steel door was invented, installed at the entrance of the house, many began to think about how to protect their home from uninvited guests. Locks are structures for protecting premises that have been manufactured for a very long time. There are various types, configurations, operating features and similar differences, however, the essence of the mechanism remains completely unchanged, since the design is designed to block access to the room. Despite the fact that there are many modern technologies, installations such as coded mechanical lock, the production of which began in the last century. Initially, they were installed on safes, and over time they were also used in installing doors in ordinary apartments, garages, entrances and private houses.

Combination lock device and DIY installation

The design of combination locks is that they do not have a keyhole, due to which they become more reliable, wear-resistant and durable. The likelihood of hacking is significantly reduced. By installing a specific coding of the cylinders and rollers that make up the lock, you can customize the lock yourself, and installation can be carried out on doors made of various materials, for example: metal, plastic and wood. It is advisable that the thickness of the door be at least 3 cm, which will also complicate the breaking process for intruders.

You can select and install a combination lock yourself if you carefully read the instructions

The diagram for installing a lock on the front door with your own hands is very simple, since for this you need:

Select a door locking mechanism relative to the width and thickness of the structure;
Make a marking of the future location of the product;
Using a drill, drill holes in the door to install the lock body;
Install the code panel;
Assemble the locking mechanism;
Carry out installation and fixation of prefabricated parts of the mechanism;

Finally, you need to set up the code combination and check the functionality of the product.

How to make a combination lock: choosing a variety

To install a push-button door lock, you will first need to select its type. They are: overhead and mortise. To install a surface-type lock, simply install it on the surface of the door, and the bar with the bolt located in it on the jamb of the door frame. Installation will not require more than 15 minutes. Installing a mortise combination lock can cause a lot of trouble and this is where special attention and a competent approach are required.

Making a combination lock is not difficult, the main thing is to approach this process competently

As a rule, each magnetic door lock has instructions from the manufacturer, which must be followed as clearly as possible:

A lock template is created, which is done by hand. Some manufacturers include it in the kit, and this greatly simplifies the installation process. Using chalk or a pencil, you need to apply markings to the door leaf. Thus, the location of the structure will be marked on the door on both sides.
To make a niche on the door leaf for installing a lock, you can use a chisel or a special drill attachment.
Next, holes are drilled to install the bolts.
Where the crossbar of the lock structure is located, you need to make a recess, and the dimensions must fully correspond to the front plate.
After completing such work, the combination lock is placed in its rightful place and securely bolted.
The face plate is being installed.
It is necessary to make markings on the door jamb for mounting the locking strip, into which the bolt will be placed. To implement this process It is enough to lubricate one of the crossbars with chalk, due to which a mark will be made on the jamb.
A recess is made in the jamb for the plank, and you also need to make markings for the holes in order to install it. The installation process fully corresponds to the installation of the front strip.
Finally, you need to secure the counter or locking part of the lock.

Judging by the steps described above, we can conclude that installing a mortise combination lock is similar to installing other types of locks in the same way.

Combination lock repair

To make repairs on a structure such as a digital combination lock, it will not require too much effort, since the main repair work consists of recoding the structure. In addition, preventative recoding is periodically required to increase the safety of the product.

In order to repair the combination lock, it will need to be properly disassembled.

To change the code on the lock, partial disassembly of the structure is required to gain access to the buttons from the inside, for which you need to unscrew the cover with the buttons.

Next, you need to pay attention to the plates located inside, when pressed, the locking mechanism is activated, and each of them has a specially made cut. Visually separate the working and unused plates. To replace the code, turn the required plates in the opposite direction or, in other words, make other buttons active.

DIY invisibility lock

An electronic invisible lock is an additional device that can be used to increase the security of an apartment, house or any other premises. From the outside, the electric lock is completely invisible, but inside it is a reliable installation that can prevent intruders from entering. To make such an electromagnetic lock with your own hands, you can use the most ordinary car door actuator from the central locking, and it is controlled or, in other words, blocked by the most ordinary alarm system.

An invisible combination lock is practical and convenient.

The essence of such an invisible thing is to block one keyhole bolt in the position when it is pushed forward:

Due to the fact that the car anti-theft alarm device has enough wires, and a long type, it is possible to carry out competent and easy installation.
It is necessary to select a place for subsequent installation of the actuator, since the pin that will be extended must fit exactly into the bolt when it is extended.
Next, you need to make precise markings on the top strip of the door frame, and it is drilled. Then a mark will be made on the crossbar, along which an additional through hole will be drilled.
When the bolt is drilled into the hole, a countersink is made so that the actuator pin fits there as accurately as possible.
Using the strip that comes with the kit, you need to secure the actuator to the door frame.
Next, a guide from 1 pin and a limit switch are installed on the door frame so that it is triggered to open the door.
Installation of the alarm unit, as well as all related elements located in a decorative metal box, is required. The box is installed on the wall surface next to the door on the inside of the room.
The box closes tightly.
Connects to the doorbell button LED indicator or in other words an alarm.
The structure is ready for use.

If a power connection is required, this can be done using a stabilized unit, which has an output voltage of 12 V and a current of at least 1 A. To increase the autonomy of the device relative to the network voltage, you can use a battery from a car to power such a lock, which will be located in pantry or on the balcony.

Types of combination mechanical locks (video)

It is not difficult to make such a structure, but you need to follow the recommendations and sequence of actions. It is very important that all wires connected to the battery and the alarm itself are in good working order and carefully insulated, which will prevent the formation of sparks and interruptions in the operation of the system.

Similar materials

From this article you can learn how to make a simple combination lock with little financial investment. If we are not talking about daring hacking using brute physical force, then choosing a combination for this combination lock may take years.
The circuit for this combination lock was found on the Internet, but after assembly the device did not function due to two basic resistors. Their resistance had to be reduced in order for everything to work as it should.

When the first pulse is applied to the input, the counter starts working - reading pulses, and a logical unit appears at pin 2.

When you press the S2 button, the unit again enters input 14, and the 4th output opens, then the 7th and the last 10th. The signal from the latter goes to the base of the transistor, and it fires, and you can now control any load, for example, the winding of an electromagnetic relay for switching network loads.

It should be noted that the microcircuit has 10 working pins, and if desired, you can set a nine-digit code.
In standby mode, the board consumes only a few mA, and the power supply ammeter did not even react to them during measurements.

Attached files:

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