In the eighties of the last century, the magazine “Radio” published a schematic diagram of a drill speed controller, reprinted from a Bulgarian magazine on radio electronics. The parts in this diagram were made abroad. In 1985, I made this drill speed controller from domestic parts and still works properly.

Currently, imported and domestic drills are produced with speed controllers, but there are many early production drills that do not provide for changing the speed, which, of course, reduces the operational capabilities of the drill.

In Fig. Figure 1 shows a diagram of a drill speed controller, manufactured as a separate unit and, as tests have shown, suitable for any drills with a power of up to 1.8 kW, as well as for any devices that use a collective

AC motor, for example, in angle grinders, so-called grinders. I selected domestic regulator parts for my drill brand S480B (n=650 rpm, power 270 W, voltage 220 V).

Resistors:

R, - 7 kOhm (assembled from two parallel-connected resistors with a nominal value of 12 kOhm and 18 kOhm, type MLT2, power 2 W each\

R 2 - 2.2 kOhm type SP variable, power 1 W;

R 3 - 51 Ohm MLT type, power 0.125 W;

Capacitor C, - 2 μF (actually assembled from two series-connected capacitors with a capacity of 4 μF, type MBGO-2, operating voltage 160 V).

Diodes: VD1 and VD2 - type D7Zh (forward current 300 mA and reverse voltage U^p = 400 V). Diodes D226, D237B, KD-221V, MD226 have similar parameters.

Thyristor VT1 - type KU202N (reverse voltage U^ = 400 V, open current J oc = 10 A). Thyristors 2U202M, 2U202N, KU202M have the same parameters.

From a drill, with the help of additional devices, you can make various devices that will replace various machines, such as drilling, lathe, grinding and others. But if drill machines do not have the ability to regulate the rotation speed, then working on them will not be very convenient.

Modern drills are often equipped with a speed regulator in the form of a trigger. In this case, the rotation speed depends on the degree of pressure. At the same time, the trigger lock does not fix the trigger at the selected rotation speed in all models of drills, but only locks the trigger when the maximum pressure is applied, that is, at maximum speed, which can negate such a speed controller. Another disadvantage of the built-in regulator is that when the drill is inserted into any device, it may be in a position in which it is inconvenient to use the speed regulator, even if it has no other disadvantages.

For drill machines, it is more convenient to use an external regulator, which eliminates the disadvantages described above. You can make such a regulator from a dimmer (lighting regulator) and a socket. The schematic diagram of such a regulator is as follows:

The implementation of this scheme may vary. We will present two options that are not the best from a security point of view. Of course, the regulator must be made so that the inside is closed on all sides, and not as it is done in the pictures.

It is very convenient to use such a speed regulator; the regulator plug is inserted into the mains socket, and the drill plug into the regulator socket. The drill trigger is fixed in the fully pressed position, and the rotation speed is controlled by turning the dimmer knob. It is only necessary that the power of the drill does not exceed the power of the dimmer. Such a regulator can be used not only to regulate the rotation speed, but also to control the heating of a soldering iron or boiler.

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Today it is impossible to find a person who does not know about the existence of an electric drill. Many people have had to use this tool. But not everyone knows how this irreplaceable household thing works.

Inside the drill body there is an electric motor, its cooling system, a gearbox, and a drill speed controller. It’s worth talking about the operation of the drill speed controller in a little more detail. All parts wear out during operation, the drill power button is especially susceptible to this process. And the speed control system is directly connected to it.

Purpose of the speed controller

The speed control of a modern electric drill is located inside the power button of the device. The microfilm technology used to assemble it makes it possible to achieve such small sizes. All parts and the board itself on which these parts are located are small in size. The main part of the regulator is a triac. The principle of its operation is to change the moment of closing the circuit and turning on the triac. It happens like this:

1. After turning on the button, the triac receives a sinusoidal voltage to its control electrode.
2. The triac opens and current begins to flow through the load.

With a larger amplitude of the control voltage, the triac turns on earlier. The amplitude is controlled using a variable resistor, which is connected to the trigger of the drill. The button connection diagram may be slightly different in different models. Just don’t confuse the speed controller with the reverse control device. These are completely different things. Sometimes they can be located in different buildings. The speed controller may provide for connecting a capacitor and both wires from the outlet.

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Using a drill as a machine tool

Figure 1. Typical diagram of a drill speed controller.

A hand drill can be used in non-standard ways. A variety of machines are made on its basis: drilling, grinding, circular and others. In such machines, the speed control function is very important. For most household drills, the speed is regulated by the device's start button. The harder it is pressed, the higher the speed. But they are fixed only at maximum values. In most cases this can be a significant drawback.

You can get out of this situation by making your own remote version of the speed controller. As a regulator, it is quite possible to use a dimmer, which is usually used to regulate lighting. The regulator circuit is quite simple and is shown in Fig. 1. To make it, you need to connect wires of different lengths to the socket. The other end of the long wire is connected to the plug. The rest is assembled according to the scheme. It is recommended to use an additional circuit breaker that will turn off the device in the event of an emergency.

The homemade speed controller is ready. You can perform a test run. If it works normally, you can place it in a suitable sized box and attach it to the frame of the future machine in a convenient place.

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Repair of a button with speed control

Figure 2. Diagram of a speed controller for a microdrill.

Repairing a button is a rather complicated process that requires certain skills. When opening the case, some parts may simply fall out and get lost. Therefore, caution is needed in work. In case of problems, the triac usually fails. This part is very cheap. Disassembly and repair occur in the following order:

1. Disassemble the button housing.
2. Rinse and clean the insides.
3. Remove the board with the circuit on it.
4. Remove the burnt part.
5. Solder a new part.

It is very easy to disassemble the case. You need to bend the sides and remove the cover from the latches. Everything must be done carefully and carefully so as not to lose 2 springs that may jump out. It is recommended to clean and wipe the insides with alcohol. Clip-contacts in the shape of copper squares slide out of the grooves, and the board is easily removed. A burnt triac is usually clearly visible. All that remains is to unsolder it and solder a new part in its place. The regulator is reassembled in the reverse order.

(angle grinders), commonly known among Bulgarians, have a speed regulator.

The speed regulator is located on the body of the angle grinder

Consideration of various adjustments should begin with an analysis of the electrical circuit of the angle grinder.

simple representation of the electrical circuit of a grinding machine

More advanced models automatically maintain rotation speed regardless of the load, but tools with a manual disk are more common. If a trigger-type regulator is used on a drill or electric screwdriver, then such a regulation principle is impossible on an angle grinder. Firstly, the features of the tool require a different grip when working. Secondly, adjustment during operation is unacceptable, so the speed value is set with the engine turned off.

Why adjust the rotation speed of the grinder disc at all?

1. When cutting metal of different thicknesses, the quality of work greatly depends on the speed of rotation of the disk.
   If you are cutting hard and thick material, you must maintain maximum rotation speed. When processing thin sheet metal or soft metal (for example, aluminum), high speeds will lead to melting of the edge or rapid blurring of the working surface of the disk;
2. Cutting and sawing stone and tile at high speed can be dangerous.
   In addition, the disk, which rotates at high speeds, knocks small pieces out of the material, making the cutting surface chipped. Moreover, different speeds are selected for different types of stone. Some minerals are processed at high speeds;
3. Grinding and polishing work is in principle impossible without adjusting the rotation speed.
   By setting the speed incorrectly, you can damage the surface, especially if it is a paint coating on a car or a material with a low melting point;
4. The use of discs of different diameters automatically implies the presence of a regulator.
   Changing a disk Ø115 mm to Ø230 mm, the rotation speed must be reduced by almost half. And it’s almost impossible to hold a 230 mm disc rotating at 10,000 rpm in your hands;
5. Polishing of stone and concrete surfaces, depending on the type of crowns used, is carried out at different speeds. Moreover, when the rotation speed decreases, the torque should not decrease;
6. When using diamond discs, it is necessary to reduce the number of revolutions, since their surface quickly fails due to overheating.
   Of course, if your grinder works only as a cutter for pipes, angles and profiles, you won’t need a speed controller. And with the universal and versatile use of angle grinders, it is vital.

There is probably no person who has not heard of the existence of an electric drill. Many have even used it, but not many people know the structure of the drill and how it works. This article will help eliminate this gap.

Drill structure (the simplest Chinese electric drill): 1 - speed controller, 2 - reverse, 3 - brush holder with a brush, 4 - motor stator, 5 - impeller for cooling the electric motor, 6 - gearbox.

Electric motor. The commutator electric motor of a drill contains three main elements - a stator, an armature and carbon brushes. The stator is made of electrical steel with high magnetic permeability. It has a cylindrical shape and grooves for laying stator windings. There are two stator windings and they are located opposite each other. The stator is rigidly mounted in the drill body.

Drill structure: 1 - stator, 2 - stator winding (second winding under the rotor), 3 - rotor, 4 - rotor commutator plates, 5 - brush holder with brush, 6 - reverse, 7 - speed controller.

Speed ​​controller. The drill speed is controlled by a triac regulator located in the power button. It should be noted that there is a simple adjustment scheme and a small number of parts. This regulator is assembled in a button body on a PCB substrate using microfilm technology. The board itself has miniature dimensions, which made it possible to place it in the trigger body. The key point is that in the drill regulator (in the triac) the circuit opens and closes in milliseconds. And the regulator does not change the voltage that comes from the outlet in any way ( however, the root mean square value of the voltage changes, which is shown by all voltmeters that measure alternating voltage). More precisely, pulse-phase control occurs. If the button is pressed lightly, then the time when the circuit is closed is the shortest. As you press, the time the circuit is closed increases. When the button is pressed to the limit, the time the circuit is closed is maximum or the circuit does not open at all.

Voltage diagrams: in the network (at the regulator input), at the control electrode of the triac, at the load (at the regulator output).

It is shown how the voltage at the output of the regulator will change if the drill trigger is pulled.

Electrical diagram of a drill. "reg. rev." — electric drill speed regulator, “1st rotation station.” - first stator winding, “2nd stator winding.” - second stator winding, “1st brush.” - first brush, “2nd brush.” - second brush.

The speed controller and reverse are located in separate housings. The photo shows that only two wires are connected to the speed controller.

Drill reverse circuit

Diagram on the reverse of an electric drill (in the photo the reverse is disconnected from the speed controller)

Electric drill reverse connection diagram

Connection diagram for the button (speed control) of the drill.

Connecting an electric drill button

Gearbox. The drill gearbox is designed to reduce drill speed and increase torque. A gear reducer with one gear is more common. There are drills with several gears, for example two, and the mechanism itself is somewhat reminiscent of a car gearbox.

Impact action of the drill. Some drills have an impact mode for making holes in concrete walls. To do this, a wavy “washer” is placed on the side of the large gear, and the same “washer” is placed opposite.

Large gear with wavy side

When drilling with the impact mode turned on, when the drill rests, for example, on a concrete wall, the wavy “washers” come into contact and, due to their waviness, imitate impacts. The “washers” wear out over time and require replacement.

Wavy surfaces do not touch thanks to the spring

Touching wavy surfaces. The spring is stretched.

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Automatic speed controller for micro drill

Automatic speed controller for micro drill

A design that captivated with its repeatability and ease of use. The scheme was invented and implemented back in 1989 by Bulgarian Alexander Savov:

The circuit of the automatic speed controller of a micro drill is simple to implement, built on the basis of the LM385 op amp; the operating principle is not drilling - the speed is minimal. We put a load on the drill, the speed increases to the maximum.

The circuit uses easily accessible parts.

The LM317 chip must be installed on a radiator to avoid overheating.
Electrolytic capacitors with a rated voltage of 16V.
1N4007 diodes can be replaced with any other ones rated for a current of at least 1A.
LED AL307 any other. The printed circuit board is made on single-sided fiberglass.
Resistor R5 with a power of at least 2W, or wirewound.
The power supply must have a current reserve for a voltage of 12V.

The regulator is operational at a voltage of 12-30V, but above 14V you will have to replace the capacitors with ones corresponding to the voltage. The finished device starts working immediately after assembly.

Resistor P1 sets the required idle speed. Resistor P2 is used to set the sensitivity to the load; we use it to select the desired moment of increasing speed. If you increase the capacitance of capacitor C4, the delay time at high speeds will increase or if the engine runs jerkily.
I increased the capacitance to 47uF.
The engine is not critical for the device. It just needs to be in good condition.
I suffered for a long time, I already thought that the circuit was a glitch, that it was unclear how it regulates the speed, or reduces the speed during drilling.
But I disassembled the engine, cleaned the commutator, sharpened the graphite brushes, lubricated the bearings, and reassembled it.
Installed spark arresting capacitors. The scheme worked great.
Now you don't need an inconvenient switch on the micro drill body.

The scheme works great:

1. small load - the chuck does not rotate quickly.

The circuit is completely indifferent to which motors it works with:

A grinder with a speed controller has more capabilities than a simpler version of a power tool.

If the angle grinder is not equipped with a speed controller, is it possible to install it yourself?
Most angle grinders (angle grinders), commonly known as grinders, have a speed regulator.

The speed regulator is located on the body of the angle grinder

Consideration of various adjustments should begin with an analysis of the electrical circuit of the angle grinder.

simple representation of the electrical circuit of a grinding machine

More advanced models automatically maintain rotation speed regardless of the load, but tools with manual adjustment of disk speed are more common. If a trigger-type regulator is used on a drill or electric screwdriver, then such a regulation principle is impossible on an angle grinder. Firstly, the features of the tool require a different grip when working. Secondly, adjustment during operation is unacceptable, so the speed value is set with the engine turned off.

Why adjust the rotation speed of the grinder disc at all?

1. When cutting metal of different thicknesses, the quality of work greatly depends on the speed of rotation of the disk.
   If you are cutting hard and thick material, you must maintain maximum rotation speed. When processing thin sheet metal or soft metal (for example, aluminum), high speeds will lead to melting of the edge or rapid blurring of the working surface of the disk;
2. Cutting and sawing stone and tile at high speed can be dangerous.
   In addition, the disk, which rotates at high speeds, knocks small pieces out of the material, making the cutting surface chipped. Moreover, different speeds are selected for different types of stone. Some minerals are processed at high speeds;
3. Grinding and polishing work is in principle impossible without adjusting the rotation speed.
   By setting the speed incorrectly, you can damage the surface, especially if it is a paint coating on a car or a material with a low melting point;
4. The use of discs of different diameters automatically implies the presence of a regulator.
   Changing a disk Ø115 mm to Ø230 mm, the rotation speed must be reduced by almost half. And holding a grinder with a 230 mm disc rotating at a speed of 10,000 rpm is almost impossible to hold in your hands;
5. Polishing of stone and concrete surfaces, depending on the type of crowns used, is carried out at different speeds. Moreover, when the rotation speed decreases, the torque should not decrease;
6. When using diamond discs, it is necessary to reduce the number of revolutions, since their surface quickly fails due to overheating.
   Of course, if your grinder works only as a cutter for pipes, angles and profiles, you won’t need a speed controller. And with the universal and versatile use of angle grinders, it is vital.

Typical speed controller circuit

This is what the assembled speed controller board looks like

The engine speed controller is not just a variable resistor that lowers the voltage. Electronic control of the current strength is necessary, otherwise, as the speed drops, the power and, accordingly, the torque will decrease proportionally. In the end, a critically low voltage value will occur when, even with the slightest resistance of the disk, the electric motor simply cannot turn the shaft.
Therefore, even the simplest regulator must be calculated and implemented in the form of a well-developed circuit.

And more advanced (and therefore expensive) models are equipped with regulators based on an integrated circuit.

Integrated controller circuit. (the most advanced option)

If we consider the electrical circuit of the angle grinder in principle, it consists of a speed controller and a soft start module. Power tools equipped with advanced electronic systems are significantly more expensive than their simpler counterparts. Therefore, not every home craftsman is able to purchase such a model. And without these electronic units, all that remains is the electric motor winding and the power button.

The reliability of modern electronic components of angle grinders exceeds the service life of motor windings, so you should not be afraid of purchasing a power tool equipped with such devices. The only limiting factor can be the price of the product. Moreover, users of inexpensive models without a regulator sooner or later come to install it themselves. The block can be purchased ready-made or made independently.

Making a speed controller with your own hands

Trying to adapt a regular dimmer to adjust the brightness of the lamp will not yield anything. Firstly, these devices are designed for a completely different load. Secondly, the operating principle of the dimmer is not compatible with controlling the electric motor winding. Therefore, you have to mount a separate circuit and figure out how to place it in the tool body.

IMPORTANT! If you do not have the skills to work with electrical circuits, it is better to purchase a ready-made factory regulator, or an angle grinder with this function.

Homemade speed controller

The simplest thyristor rotation speed controller can easily be made independently. To do this, you will need five radio elements, which are sold on any radio market.

Electrical circuit of a thyristor speed controller for your instrument

The compact design allows the circuit to be placed in the body of an angle grinder without compromising ergonomics and reliability. However, this scheme does not allow maintaining torque when the speed drops. This option is suitable for reducing speed when cutting thin sheet metal, carrying out polishing work, and processing soft metals.

If your grinder is used for stone processing, or discs larger than 180 mm in size can be installed on it, you need to assemble a more complex circuit, where the KR1182PM1 microcircuit, or its foreign equivalent, is used as a control module.

Electrical circuit for speed control using the KR1182PM1 microcircuit

This circuit controls the current strength at any speed, and allows you to minimize the loss of torque when they decrease. In addition, this scheme is more gentle on the engine, extending its life.

The question of how to adjust the speed of the tool arises when it is stationary. For example, when using a grinder as a circular saw. In this case, the connection point (machine or socket) is equipped with a regulator, and the speed is adjusted remotely.

Regardless of the method of execution, the angle grinder speed controller expands the capabilities of the tool and adds comfort when using it.

Sergey | 06/28/2016 00:10

Quote: “Most angle grinders (angle grinders), commonly known as grinders, have a speed regulator.” Only a person who has never bought an angle grinder can write this way. Go to the construction supermarket in the power tools section and count how many angle grinders with speed control there will be - you might find 5 out of 20.

sposport | 06/28/2016 11:44

Full of grinders with speed control. Perhaps the word “advanced” or “expensive” is missing, we can agree with this. And the fact that the stores are jam-packed with no idea what’s going on, it’s different from market to market.

erikra | 08/25/2016 19:37

DIY electric drill repair

If you have certain skills, repairing a drill at home is quite simple. From the numerous cases of drill breakdowns, several characteristic malfunctions can be identified, which are caused by improper operation of the power tool or defective elements from the manufacturer. Such typical breakdowns include:

— failure of engine elements (stator, armature).
— wear of the brushes or their burning.
— failure of the regulator and reverse switch.
- wear of support bearings.
— poor quality clamp in the tool chuck.

The structure of an electric drill (the simplest Chinese electric drill):
1 — speed regulator, 2 — reverse, 3 — brush holder with brush, 4 — motor stator, 5 — impeller for cooling the electric motor, 6 — gearbox.

The commutator electric motor of a drill contains three main elements - a stator, an armature and carbon brushes. The stator is made of electrical steel with high magnetic permeability. It has a cylindrical shape and grooves for laying stator windings. There are two stator windings and they are located opposite each other. The stator is rigidly mounted in the drill body.

Electric drill device:
1 - stator, 2 - stator winding (second winding under the rotor), 3 - rotor, 4 - rotor commutator plates, 5 - brush holder with brush, 6 - reverse, 7 - speed controller.

The rotor is a shaft onto which an electrical steel core is pressed. Along the entire length of the core, grooves are machined at equal distances for laying armature windings. The windings are wound with a solid wire with taps for attachment to the collector plates. Thus, an anchor is formed, divided into segments. The collector is located on the shaft shank and is rigidly mounted on it. During operation, the rotor rotates inside the stator on bearings located at the beginning and end of the shaft.

Spring-loaded brushes move along the plates during operation. By the way, when repairing a drill, special attention should be paid to them. The brushes are pressed from graphite and have the shape of a parallelepiped with built-in flexible electrodes.

The most common type of breakdown is wear of the motor brushes, which can be replaced yourself at home. Sometimes, brushes can be replaced without disassembling the drill body. For some models, it is enough to unscrew the plugs from the installation windows and install new brushes. For other models, replacement requires disassembling the housing; in this case, you must carefully remove the brush holders and remove the worn brushes from them.

Brushes are sold at all normal power tool stores, and often an extra pair of brushes is included with a new electric drill.

Don't wait for the brushes to wear down to their minimum size. This risks increasing the gap between the brush and the collector plates. As a result, increased sparking occurs, the commutator plates become very hot and may move away from the base of the commutator, which will lead to the need to replace the armature.

You can determine the need to replace brushes by increased sparking, which can be seen in the ventilation slots of the housing. The second way to determine this is the chaotic jerking of the drill during operation.

In second place, in terms of the number of drill breakdowns, can be placed the malfunction of engine components and, most often, the armature. Failure of an armature or stator occurs for two reasons - improper operation and poor-quality winding wire. World-famous manufacturers use expensive coil wire with double insulation with heat-resistant varnish, which significantly increases the reliability of engines. Accordingly, in cheap models the quality of insulation of the winding wire leaves much to be desired. Improper operation comes down to frequent overloading of the drill or prolonged operation without breaks to cool the engine. Repairing a drill with your own hands by rewinding the armature or stator, in this case, is impossible without special tools. Only complete replacement of the element (exclusively experienced repairmen will be able to rewind the armature or stator with their own hands).

To replace the rotor or stator, it is necessary to disassemble the housing, disconnect the wires, brushes, remove the drive gear if necessary, and remove the entire motor along with the support bearings. Replace the faulty element and install the engine in place.

An armature malfunction can be determined by a characteristic smell, an increase in sparking, and the sparks have a circular motion in the direction of movement of the armature. Pronounced “burnt” windings can be seen upon visual inspection. But if the engine power has dropped, but there are no signs described above, then you should resort to the help of measuring instruments - an ohmmeter and a megohmmeter.

The windings (stator and armature) are subject to only three damages - interturn electrical breakdown, breakdown to the casing (magnetic circuit) and winding breakage. A breakdown to the housing is determined quite simply; it is enough to touch any winding output and magnetic circuit with the probes of a megohmmeter. A resistance of more than 500 MΩ indicates no breakdown. It should be taken into account that measurements should be carried out with a megger with a measuring voltage of at least 100 volts. By taking measurements with a simple multimeter, it is impossible to accurately determine that there is definitely no breakdown, but you can determine that there is definitely a breakdown.

It is quite difficult to determine the interturn breakdown of the armature, unless, of course, it is visible visually. To do this, you can use a special transformer, which has only a primary winding and a break in the magnetic circuit in the form of a trench for installing an armature into it. In this case, the armature with its core becomes a secondary winding. Rotating the armature so that the windings alternate in operation, we apply a thin metal plate to the armature core. If the winding is short-circuited, the plate begins to rattle strongly, and the winding heats up noticeably.

Often, an interturn short circuit is detected in visible areas of the wire or armature bar: the turns may be bent, crumpled (i.e., pressed against each other), or there may be some conductive particles between them. If so, then it is necessary to eliminate these short circuits by correcting bruises in the tire or removing foreign bodies, respectively. Also, a short circuit can be detected between adjacent collector plates.

You can determine whether the armature winding is broken if you connect a milliammeter to the adjacent armature plates and gradually turn the armature. In whole windings a certain identical current will appear; a broken winding will show either an increase in current or its complete absence.

A break in the stator windings is determined by connecting an ohmmeter to the disconnected ends of the windings; the absence of resistance indicates a complete break.

The drill speed is controlled by a triac regulator located in the power button. It should be noted that there is a simple adjustment scheme and a small number of parts. This regulator is assembled in a button body on a PCB substrate using microfilm technology. The board itself has miniature dimensions, which made it possible to place it in the trigger body. The key point is that in the drill regulator (in the triac) the circuit opens and closes in milliseconds. And the regulator does not change the voltage that comes from the outlet in any way (however, the root mean square value of the voltage changes, which is shown by all voltmeters that measure alternating voltage). More precisely, pulse-phase control occurs. If the button is pressed lightly, then the time when the circuit is closed is the shortest. As you press, the time the circuit is closed increases. When the button is pressed to the limit, the time the circuit is closed is maximum or the circuit does not open at all.

More scientifically it looks like this. The principle of operation of the regulator is based on changing the moment (phase) of turning on the triac (circuit closure) relative to the transition of the mains voltage through zero (the beginning of the positive or negative half-wave of the supply voltage).

Voltage diagrams: in the network (at the regulator input), at the control electrode of the triac, at the load (at the regulator output).

To make it easier to understand the operation of the regulator, we will construct three time diagrams of voltages: mains voltage, at the control electrode of the triac, and at the load. After turning on the drill, an alternating voltage is supplied to the regulator input (top diagram). At the same time, a sinusoidal voltage is applied to the control electrode of the triac (middle diagram). At the moment when its value exceeds the switching voltage of the triac, the triac will open (the circuit will close) and the mains current will flow through the load. After the control voltage drops below the threshold, the triac remains open due to the fact that the load current exceeds the holding current. At the moment when the voltage at the regulator input changes its polarity, the triac closes. Then the process is repeated. Thus, the voltage across the load will have the shape as in the bottom diagram.

The greater the amplitude of the control voltage, the earlier the triac will turn on, and therefore, the longer the duration of the current pulse in the load. And vice versa, the smaller the amplitude of the control signal, the shorter the duration of this pulse will be. The amplitude of the control voltage is controlled by a variable resistor connected to the drill trigger. The diagram shows that if the control voltage is not phase-shifted, the control range will be from 50 to 100%. Therefore, in order to expand the range, the control voltage is shifted in phase, and then during the processes of pressing the trigger, the voltage at the output of the regulator will change as shown in the figure below.

It is shown how the voltage at the output of the regulator will change if the drill trigger is pulled.

Speed ​​controller repair.

The presence of voltage at the input terminals of the power button and absence at the output terminals indicates a malfunction of the contacts or components of the speed controller circuit. You can disassemble the button by carefully picking up the latches of the protective casing and pulling it off the button body. A visual inspection of the terminals will allow you to judge their performance. Blackened terminals are cleaned of carbon deposits with alcohol or fine sandpaper. Then the button is reassembled and checked for contact; if nothing has changed, then the button with the regulator must be replaced. The speed controller is made on a substrate and is completely filled with an insulating compound, so it cannot be repaired. Another typical malfunction of the button is the erasure of the working layer under the rheostat slider. The easiest way out is to replace the entire button.

Repairing a drill button with your own hands is only possible if you have certain skills. It is important to understand that after opening the case, many switching parts will simply fall out of the case. This can be prevented only by smoothly lifting the cover initially and sketching the location of the contacts and springs.

Reverse device(if it is not located in the button body) has its own changeover contacts, therefore it is also susceptible to contact loss. The disassembly and cleaning mechanism is the same as the buttons.

When purchasing a new speed controller, you should make sure that it is designed for the power of the drill, so with a drill power of 750W, the regulator must be designed for a current of more than 3.4A (750W/220V=3.4A).

The wiring diagram, and in particular the drill button connection diagram, may differ in different models. The simplest diagram, and best demonstrating the principle of operation, is the following. One lead from the power cord is connected to the speed controller.

Electrical diagram of a drill.
"reg. rev."- electric drill speed controller, "1st station exchange"- first stator winding, “2nd station exchange.”- second stator winding, "1st brush."- first brush, "2nd brush."- second brush.

To avoid confusion, it is important to understand that the speed controller and the reverse control device are two different parts that often have different housings.

The speed controller and reverse are located in separate housings. The photo shows that only two wires are connected to the speed controller.

The only wire coming out of the speed controller is connected to the beginning of the first stator winding. If there were no reversing device, the end of the first winding would be connected to one of the rotor brushes, and the second rotor brush would be connected to the beginning of the second stator winding. The end of the second stator winding leads to the second wire of the power cord. That's the whole scheme.

A change in the direction of rotation of the rotor occurs when the end of the first stator winding is connected not to the first, but to the second brush, while the first brush is connected to the beginning of the second stator winding.

This switching occurs in the reverse device, so the rotor brushes are connected to the stator windings through it. This device may have a diagram showing which wires are connected internally.

Reverse diagram of an electric drill
(in the photo the reverse is disconnected from the speed controller).

Electric drill reverse connection diagram.

Black wires lead to the rotor brushes (let the 5th contact be the first brush, and let the 6th contact be the second brush), gray wires lead to the end of the first stator winding (let there be the 4th contact) and the beginning of the second (let there be 7- th contact). When the switch is in the position shown in the photo, the end of the first stator winding with the first rotor brush (4th with 5th), and the beginning of the second stator winding with the second rotor brush (7th with 6th) are closed. When switching the reverse to the second position, the 4th is connected to the 6th, and the 7th to the 5th.

The design of the electric drill speed controller provides for connecting a capacitor and connecting both wires coming from the outlet to the controller. The diagram in the figure below, for better understanding, is slightly simplified: there is no reverse device, the stator windings to which the wires from the regulator are connected are not yet shown (see diagrams above).

Connection diagram for the button (speed control) of the drill.

In the case of the described electric drill, only two lower contacts are used: the far left and the far right. There is no capacitor, and the second wire of the power cord is connected directly to the stator winding.

Connecting an electric drill button.

The drill gearbox is designed to reduce drill speed and increase torque. A gear reducer with one gear is more common. There are drills with several gears, for example two, and the mechanism itself is somewhat reminiscent of a car gearbox.

The presence of extraneous sounds, grinding and jamming of the cartridge indicates a malfunction of the gearbox or gear shift mechanism, if any. In this case, it is necessary to inspect all gears and bearings. If worn splines or broken teeth are found on the gears, then a complete replacement of these elements is necessary.

Bearings are checked for suitability after removing them from the armature axis or drill body using special pullers. While holding the inner race with two fingers, you need to rotate the outer race. Uneven slipping of the race or a rustling sound when turning indicates the need to replace the bearing. A bearing replaced at the wrong time will lead to jamming of the armature, or, in the best case, the bearing will simply turn in its seat.

Impact action of the drill.

Some drills have an impact mode for making holes in concrete walls. To do this, a wavy washer9 is placed on the side of the large gear, and the same washer9 opposite.

A large gear with a wavy side.

When drilling with the impact mode turned on, when the drill rests, for example, on a concrete wall, the wavy washers9 come into contact and, due to their waviness, imitate impacts. “The washers9 wear out over time and require replacement.

The wavy surfaces do not touch thanks to the spring.

Touching wavy surfaces. The spring is stretched.

Replacing the drill chuck.

The chuck is subject to wear, namely the clamping jaws9, due to the ingress of dirt and abrasive residues of building materials. If the cartridge needs to be replaced, it is necessary to unscrew the locking screw inside the cartridge (left-hand thread) and unscrew it from the shaft.

The cord is checked with an ohmmeter, one probe is connected to the contact of the power plug, the other to the core of the cord. Lack of resistance indicates a break. In this case, repairing the drill comes down to replacing the power cord.

In custody I would like to add: when assembling the drill after repairing it, make sure that the wires are not pinched by the top cover. If everything is in order, the two halves will collapse without a gap. Otherwise, when tightening the screws, the wires may become flattened or cut.

Types of drill button connection diagrams

An electric drill is an indispensable assistant in all types of home repairs: it can be used to perform a number of tasks from mixing paints, wallpaper glue to its main purpose - drilling various holes. The product's power button wears out quickly and has to be repaired or replaced with a new one quite often. To carry out this rather simple operation, the user needs a drill button connection diagram and knowledge of the most common malfunctions of this important part.

Diagnosis of failure

This simple-looking device, during use, gives signals to the user that he will soon need repairs, but not everyone understands them. If the drill begins to work with temporary interruptions or the button requires pressing harder than before, then these are the first symptoms of incorrect operation of this part.

When you use a cordless drill, the first thing you need to do is measure the battery voltage with a tester - if it is less than the nominal value, then it needs to be charged.

In this case, we are especially interested in the condition and functionality of the product’s on/off button. It is quite simple to check that it is working properly: you need to unscrew the fastenings of the main body, remove the top cover and check the voltage of the wires going to the device by plugging the power cord into a power outlet. When the device shows voltage supply, but when you press the button the product does not work, this indicates that it is broken or there has been a problem. burning of contacts inside the device.

Regular on/off button

Repairing or replacing a drill button is considered a simple process, but you need to have certain skills - if you open the side wall carelessly, many parts can fly apart in different directions or fall out of the case.

As written above, the button may not function due to oxidation or burnt contacts. To fix this you need take it apart. observing the following order.

1. Carefully unhook the protective cover latches and open it.
2. Remove carbon deposits on the contacts with alcohol, or clean them with sandpaper.
3. Then assemble and check.

If everything works fine, it means the reason was in the contacts, otherwise you need to button replacement .

You should know that the special layer that is applied under the rheostat slider during manufacturing often wears off - in this case the button also needs to be replaced.

Quite often, the drill button connection diagram is used to check the functionality of the entire structure: only if it is available, can partial repairs be made or the button be connected correctly if it is replaced. The diagram must come with product operating instructions. if for some reason it is not there, then you can search on the Internet.

Power button with reverse/speed control

The drill button shown in the photo, in addition to reverse, has a built-in electric motor speed controller. This design is highly complex, so it is not possible to disassemble it without special skills: as soon as you open the case, all the parts will “scatter” in different directions, because they are supported by springs. Without knowing their correct location, it will be impossible to put the entire structure back together - it’s easier to buy a new one and make the connection by checking a special diagram, which can be found on the Internet.

Modern drills are produced with reverse, so the button performs several functions at once:

• basic inclusion of the product in operation;
• adjusting the rotation speed of the electric motor;
• turning on reverse - changing the direction of rotation of the engine rotor.

Attention! The reverse control and speed controller are located in different housings - they must be checked separately.

It must be remembered that in modern products speed controller is located on a special substrate, and during manufacture it is filled with a compound - an insulating composition, which, after hardening, protects all parts from mechanical, temperature and chemical influences. Therefore, it cannot be repaired.

As can be seen from the connection diagram, when it contains a drill button along with reverse, the rotation is switched using special toggle switch. In this case, plus or minus is supplied to different brushes, so the motor armature rotates in different directions.

You should not disassemble the drill start button yourself if its design is complex - disconnect the wires and take it to a service center, where professional specialists will carry out a full diagnosis and repair.

Our assistant can drill different materials, so there is often a lot of dust and waste. After each use you should clean the drill. then the next time you use the device, it will work like a Swiss watch: without failures or annoying stops.