Powerful PWM engine speed controller. Digital PWM speed controller for commutator motor. Two-channel motor controller

On simple mechanisms it is convenient to install analog current regulators. For example, they can change the speed of rotation of the motor shaft. From the technical side, implementing such a regulator is simple (you will need to install one transistor). Suitable for adjusting independent speed of motors in robotics and power supplies. The most common two types of regulators are single-channel and two-channel.

Video No. 1. Single-channel regulator in operation. Changes the rotation speed of the motor shaft by rotating the variable resistor knob.

Video No. 2. Increasing the rotation speed of the motor shaft when operating a single-channel regulator. An increase in the number of revolutions from the minimum to the maximum value when rotating the variable resistor knob.

Video No. 3. Two-channel regulator in operation. Independent setting of the torsion speed of motor shafts based on trimming resistors.

Video No. 4. The voltage at the regulator output was measured with a digital multimeter. The resulting value is equal to the battery voltage, from which 0.6 volts have been subtracted (the difference arises due to the voltage drop across the transistor junction). When using a 9.55 volt battery, a change from 0 to 8.9 volts is recorded.

Functions and main characteristics

The load current of single-channel (photo 1) and two-channel (photo 2) regulators does not exceed 1.5 A. Therefore, to increase load capacity replace the KT815A transistor with KT972A. The numbering of the pins for these transistors is the same (e-k-b). But the KT972A model is operational with currents up to 4A.

Single channel motor controller

The device controls one motor, powered by voltage in the range from 2 to 12 volts.

1. Device design

The main design elements of the regulator are shown in the photo. 3. The device consists of five components: two variable resistance resistors with a resistance of 10 kOhm (No. 1) and 1 kOhm (No. 2), a transistor model KT815A (No. 3), a pair of two-section screw terminal blocks for the output for connecting a motor (No. 4) and input for connecting a battery (No. 5).

Note 1. Installation of screw terminal blocks is not necessary. Using a thin stranded mounting wire, you can connect the motor and power source directly.

1. Operating principle

The operating procedure of the motor controller is described in the electrical diagram (Fig. 1). Taking into account the polarity, a constant voltage is supplied to the XT1 connector. The light bulb or motor is connected to the XT2 connector. A variable resistor R1 is turned on at the input; rotating its knob changes the potential at the middle output as opposed to the minus of the battery. Through current limiter R2, the middle output is connected to the base terminal of transistor VT1. In this case, the transistor is switched on according to a regular current circuit. The positive potential at the base output increases as the middle output moves upward from the smooth rotation of the variable resistor knob. There is an increase in current, which is due to a decrease in the resistance of the collector-emitter junction in transistor VT1. The potential will decrease if the situation is reversed.

1. Materials and details

A printed circuit board measuring 20x30 mm is required, made of a fiberglass sheet foiled on one side (permissible thickness 1-1.5 mm). Table 1 provides a list of radio components.

Note 2. The variable resistor required for the device can be of any manufacture; it is important to observe the current resistance values ​​​​for it indicated in Table 1.

Note 3. To regulate currents above 1.5A, the KT815G transistor is replaced with a more powerful KT972A (with a maximum current of 4A). In this case, the printed circuit board design does not need to be changed, since the distribution of pins for both transistors is identical.

1. Build process

For further work, you need to download the archive file located at the end of the article, unzip it and print it. The regulator drawing (file) is printed on glossy paper, and the installation drawing (file) is printed on a white office sheet (A4 format).

Next, the drawing of the circuit board (No. 1 in photo. 4) is glued to the current-carrying tracks on the opposite side of the printed circuit board (No. 2 in photo. 4). It is necessary to make holes (No. 3 in photo. 14) on the installation drawing in the mounting locations. The installation drawing is attached to printed circuit board dry glue, making sure the holes match. Photo 5 shows the pinout of the KT815 transistor.

The input and output of terminal blocks-connectors are marked in white. A voltage source is connected to the terminal block via a clip. A fully assembled single-channel regulator is shown in the photo. The power source (9 volt battery) is connected at the final stage of assembly. Now you can adjust the shaft rotation speed using the motor; to do this, you need to smoothly rotate the variable resistor adjustment knob.

To test the device, you need to print a disk drawing from the archive. Next, you need to paste this drawing (No. 1) onto thick and thin cardboard paper (No. 2). Then, using scissors, a disc is cut out (No. 3).

The resulting workpiece is turned over (No. 1) and a square of black electrical tape (No. 2) is attached to the center for better adhesion of the surface of the motor shaft to the disk. You need to make a hole (No. 3) as shown in the image. Then the disk is installed on the motor shaft and testing can begin. The single-channel motor controller is ready!

Two-channel motor controller

Used to independently control a pair of motors simultaneously. Power is supplied from a voltage ranging from 2 to 12 volts. The load current is rated up to 1.5A per channel.

1. Device design

The main components of the design are shown in photo.10 and include: two trimming resistors for adjusting the 2nd channel (No. 1) and the 1st channel (No. 2), three two-section screw terminal blocks for output to the 2nd motor (No. 3), for output to the 1st motor (No. 4) and for input (No. 5).

Note:1 Installation of screw terminal blocks is optional. Using a thin stranded mounting wire, you can connect the motor and power source directly.

1. Operating principle

The circuit of the two-channel regulator is identical electrical diagram single-channel regulator. Consists of two parts (Fig. 2). The main difference: the variable resistance resistor is replaced with a trimming resistor. The rotation speed of the shafts is set in advance.

Note.2. To quickly adjust the rotation speed of the motors, the trimming resistors are replaced using a mounting wire with variable resistance resistors with the resistance values ​​indicated in the diagram.

1. Materials and details

You will need a printed circuit board measuring 30x30 mm, made of a fiberglass sheet foiled on one side with a thickness of 1-1.5 mm. Table 2 provides a list of radio components.

1. Build process

After downloading the archive file located at the end of the article, you need to unzip it and print it. The regulator drawing for thermal transfer (termo2 file) is printed on glossy paper, and the installation drawing (montag2 file) is printed on a white office sheet (A4 format).

The circuit board drawing is glued to the current-carrying tracks on the opposite side of the printed circuit board. Form holes on the installation drawing in the mounting locations. The installation drawing is attached to the printed circuit board with dry glue, and the holes must match. The KT815 transistor is being pinned. To check, you need to temporarily connect inputs 1 and 2 with a mounting wire.

Any of the inputs is connected to the pole of the power source (a 9-volt battery is shown in the example). The negative of the power supply is attached to the center of the terminal block. It is important to remember: the black wire is “-” and the red wire is “+”.

The motors must be connected to two terminal blocks, and the desired speed must also be set. After successful testing, you need to remove the temporary connection of the inputs and install the device on the robot model. The two-channel motor controller is ready!

The necessary diagrams and drawings for the work are presented. The emitters of the transistors are marked with red arrows.

Most Soviet and foreign radio amateurs are very familiar with the analog integrated timer SE555/NE555 (KR1006), produced by Signetics Corporation since the distant 1971. It is difficult to list for what purposes this inexpensive but multifunctional microcircuit has not been used over the almost half-century period of its existence. However, even with the rapid development of the electronics industry in recent years, it continues to be popular and is produced in significant volumes.
The simple circuit of an automobile PWM regulator offered by Jericho Uno is not a professional, fully debugged design, notable for its safety and reliability. This is just a small cheap experiment, assembled using available budget parts and quite satisfying minimum requirements. Therefore, its developer does not take responsibility for anything that may happen to your equipment when operating the simulated circuit.

NE555 PWM regulator circuit

• electric soldering iron;
• chip NE555;
• variable resistor 100 kOhm;
• resistors 47 Ohm and 1 kOhm 0.5W each;
• 0.1 µF capacitor;
• two diodes 1N4148 (KD522B).

Step-by-step assembly of an analog circuit

Operating principle of a PWM regulator

Watch the video of the PWM regulator working

It is convenient to regulate the supply voltage of powerful consumers using regulators with pulse width modulation. The advantage of such regulators is that the output transistor operates in switch mode, which means it has two states - open or closed. It is known that the greatest heating of the transistor occurs in a half-open state, which leads to the need to install it on a large area radiator and save it from overheating.

I suggest simple diagram PWM regulator. The device is powered from a source DC voltage 12V. With the specified instance of the transistor, it can withstand current up to 10A.

Let's consider the operation of the device: A multivibrator with an adjustable duty cycle is assembled on transistors VT1 and VT2. The pulse repetition rate is about 7 kHz. From the collector of transistor VT2, pulses are sent to key transistor VT3, which controls the load. The duty cycle is regulated by variable resistor R4. When the slider of this resistor is in the extreme left position, see the top diagram, the pulses at the output of the device are narrow, which indicates the minimum output power of the regulator. In the extreme right position, see the bottom diagram, the pulses are wide, the regulator operates at full power.

Diagram of PWM operation in KT1

Using this regulator, you can control 12 V household incandescent lamps, a DC motor with an insulated housing. If the regulator is used in a car, where the minus is connected to the body, the connection should be made through a pnp transistor, as shown in the figure.
Details: Almost any low-frequency transistors can operate in the generator, for example KT315, KT3102. Key transistor IRF3205, IRF9530. pnp transistor We will replace P210 with KT825, and the load can be connected to a current of up to 20A!

And in conclusion, it should be said that this regulator has been working in my car with an interior heating engine for more than two years.

List of radioelements

I needed to make a speed controller for the propeller. To blow away the smoke from the soldering iron and ventilate the face. Well, just for fun, pack everything into a minimum price. The easiest way to regulate a low-power DC motor, of course, is with a variable resistor, but to find a motor for such a small nominal value, and even the required power, it takes a lot of effort, and it obviously won’t cost ten rubles. Therefore, our choice is PWM + MOSFET.

I took the key IRF630. Why this one MOSFET? Yes, I just got about ten of them from somewhere. So I use it, so I can install something smaller and low-power. Because the current here is unlikely to be more than an ampere, but IRF630 capable of pulling through itself under 9A. But it will be possible to make a whole cascade of fans by connecting them to one fan - enough power :)

Now it's time to think about what we will do PWM. The thought immediately suggests itself - a microcontroller. Take some Tiny12 and do it on it. I threw this thought aside instantly.

1. I feel bad about spending such a valuable and expensive part on some kind of fan. I'll find a more interesting task for the microcontroller
2. Writing more software for this is doubly frustrating.
3. The supply voltage there is 12 volts, lowering it to power the MK to 5 volts is generally lazy
4. IRF630 will not open from 5 volts, so you would also have to install a transistor here so that it supplies a high potential to the field gate. Fuck it.

Op amps can be discarded outright. The fact is that for general-purpose op-amps, already after 8-10 kHz, as a rule, output voltage limit it begins to collapse sharply, and we need to jerk the fieldman. Moreover, at a supersonic frequency, so as not to squeak.

Comparators remain; they do not have the ability of an op-amp to smoothly change the output voltage; they can only compare two voltages and close the output transistor based on the results of the comparison, but they do it quickly and without blocking the characteristics. I rummaged through the bottom of the barrel and couldn’t find any comparators. Ambush! More precisely it was LM339, but it was in a large case, and religion does not allow me to solder a microcircuit for more than 8 legs for such a simple task. It was also a shame to drag myself to the storehouse. What to do?

And then I remembered such a wonderful thing as analog timer - NE555. It is a kind of generator where you can set the frequency, as well as the pulse and pause duration, using a combination of resistors and a capacitor. How many different craps have been made on this timer over its more than thirty-year history... Until now, this microcircuit, despite its venerable age, is printed in millions of copies and is available in almost every warehouse for a price of a few rubles. For example, in our country it costs about 5 rubles. I rummaged through the bottom of the barrel and found a couple of pieces. ABOUT! Let's stir things up right now.

How does this work
If you don’t delve deeply into the structure of the 555 timer, it’s not difficult. Roughly speaking, the timer monitors the voltage on capacitor C1, which it removes from the output THR(THRESHOLD - threshold). As soon as it reaches the maximum (the condenser is charged), the internal transistor opens. Which closes the output DIS(DISCHARGE - discharge) to ground. At the same time, at the exit OUT a logical zero appears. The capacitor begins to discharge through DIS and when the voltage on it becomes zero (full discharge), the system will switch to the opposite state - at output 1, the transistor is closed. The capacitor begins to charge again and everything repeats again.
The charge of capacitor C1 follows the path: “ R4->upper shoulder R1 ->D2", and the discharge along the way: D1 -> lower arm R1 -> DIS. When we turn the variable resistor R1, we change the ratio of the resistances of the upper and lower arms. Which, accordingly, changes the ratio of the pulse length to the pause.
The frequency is set mainly by capacitor C1 and also depends slightly on the value of resistance R1.
Resistor R3 ensures that the output is pulled to a high level - so there is an open-collector output. Which is not able to independently set a high level.

You can install any diodes, the conductors are approximately the same value, deviations within one order of magnitude do not particularly affect the quality of work. At 4.7 nanofarads set in C1, for example, the frequency drops to 18 kHz, but it is almost inaudible, apparently my hearing is no longer perfect :(

I dug into the bins, which itself calculates the operating parameters of the NE555 timer and assembled a circuit from there, for astable mode with a fill factor of less than 50%, and screwed in a variable resistor instead of R1 and R2, with which I changed the duty cycle of the output signal. You just need to pay attention to the fact that the DIS output (DISCHARGE) is via the internal timer key connected to ground, so it could not be connected directly to the potentiometer, because when twisting the regulator to its extreme position, this pin would land on Vcc. And when the transistor opens, there will be a natural short circuit and the timer with a beautiful zilch will emit magic smoke, on which, as you know, all electronics work. As soon as the smoke leaves the chip, it stops working. That's it. Therefore, we take and add another resistor for one kilo-ohm. It won’t make a difference in regulation, but it will protect against burnout.

No sooner said than done. I etched the board and soldered the components:

Everything is simple from below.
Here I am attaching a signet, in the native Sprint Layout -

And this is the voltage on the engine. Apparently small transition process. You need to put the conduit in parallel at half a microfarad and it will smooth it out.

As you can see, the frequency floats - this is understandable, because in our case the operating frequency depends on the resistors and capacitor, and since they change, the frequency floats away, but this does not matter. Throughout the entire control range, it never enters the audible range. And the entire structure cost 35 rubles, not counting the body. So - Profit!