PWM controller circuit 12 volt transmission. Powerful PWM controller

Such a PWM controller can be used to control powerful loads, including low-voltage electric motors. Today I will try to make a small superficial overview of this miracle module and show the main parts and principle of operation.

Produced naturally in China, it's a pity that many components are overwritten on the board, although it's clear what's what.

The PWM controller provides smooth power adjustment, the output voltage range is 10-50 Volts, which has been tested repeatedly. The maximum current is up to 60 amperes, and this makes it possible to use such a board to control (adjust) the speed of electric cars, scooters or bicycles. The module is just specially sharpened for such purposes due to the presence of quenching diodes, which are designed to protect the field switches from motor self-induction. For those who want to buy this product, here is the link

There are 12 three-pin components on the board in the TO220 package, each with its own heat sink, 4 of them are diodes, and the remaining 8 are field-effect transistors.

Chinese engineers have erased a lot of things on the board, including field workers (more precisely, they are not marked at all).

There is a master oscillator, at the output of which a divider is installed. Thus, two similar signals were received that go to the driver, and there are two of them.

Each driver controls a line of field workers (4 pcs), as a result, the power outputs of all field workers are connected in parallel.
The scheme is very well thought out, but the Chinese did not take into account one thing - there is no protection against short circuit at the output.

In general, this is the second similar module I have, in the first version a low-resistance shunt was installed - a conversation with the seller confirmed that this is a current shunt from which readings are taken for the protection system, that is, a drop is recorded on this particular shunt, but when the board arrived I I was shocked - there is a shunt, but the components of the protection circuit are simply not installed on the board, so the shunt plays the role of a banal jumper, as a result, this board burned out in one fine moment.

And that plateau, which we are talking about today, is still alive and well, but again, it is very vulnerable due to the lack of protection.
According to the schematic part, everything is standard - a powerful PWM speed controller for the engine, it is important not to exceed the maximum allowable input voltage (50 Volts max), otherwise the stabilizer circuit will burn out, which provides power for the PWM chip and driver.

Adjust brightness halogen lamps and other passive loads are also possible without problems. I checked the regulator under a load of 30 Amperes, the keys were barely warm, despite the small heat sinks, although this was to be expected, because PWM control is much more efficient than linear.

Digital PWM speed controller of the collector motor. kirich46 writes in June 9, 2015

CCM5D Digital DC Motor Speed ​​Controller/PWM Stepless Speed ​​Control Switch Black Price $14.47
Item received free for review

Another review on the topic of all sorts of things for homemade products. This time I will talk about the digital speed controller. The thing is interesting in its own way, but I wanted more.
For those interested, read on :)

Having in the household some low-voltage devices such as a small grinder, etc. I wanted to slightly increase their functional and aesthetic appearance. True, this did not work out, although I still hope to achieve my goal, perhaps another time, I’ll tell you about the thing itself today.
The manufacturer of this regulator is Maitech, or rather, this name is often found on all kinds of handkerchiefs and blocks for homemade products, although for some reason I did not come across the website of this company.

Due to the fact that I did not end up doing what I wanted, the review will be shorter than usual, but I will start, as always, with how it is sold and sent.
The envelope contained an ordinary ziplock bag.

The kit includes only a regulator with a variable resistor and a button, there is no hard packaging and instructions, but everything arrived intact and without damage.

There is a sticker on the back that replaces the instructions. In principle, more is not required for such a device.
The operating voltage range is 6-30 Volts and the maximum current is 8 Amps.

The appearance is quite good, dark "glass", dark gray plastic of the case, in the off state it seems generally black. By appearance off, nothing to complain about. A transport film was glued on the front.
Installation dimensions of the device:
Length 72mm (minimum case opening 75mm), width 40mm, depth excluding front panel 23mm (with front panel 24mm).
Front panel dimensions:
Length 42.5mm, width 80mm


A variable resistor comes with a handle, the handle is of course rough, but it will do for use.
The resistance of the resistor is 100KΩ, the adjustment dependence is linear.
As it turned out later, 100KΩ resistance gives a glitch. When powered by a pulsed power supply unit, it is impossible to set stable readings, the interference on the wires to the variable resistor affects, because of which the readings jump +\- 2 characters, but it would be fine to jump, along with this, the engine speed jumps.
The resistance of the resistor is high, the current is small and the wires collect all the noise around.
When powered by a linear PSU, this problem is completely absent.
The length of the wires to the resistor and the button is about 180mm.

Button, well, there's nothing special. Normally open contacts, mounting diameter 16mm, length 24mm, no illumination.
The button turns off the engine.
Those. when power is applied, the indicator turns on, the engine starts, pressing the button turns it off, the second press turns it on again.
When the engine is off, the indicator also does not light up.

Under the cover is the device board.
The power supply and motor connection contacts are brought out to the terminals.
The positive contacts of the connector are connected together, the power switch switches the negative wire of the engine.
The connection of the variable resistor and the button is detachable.
Everything looks neat. The capacitor leads are a bit crooked, but I think that this can be forgiven :)

The indicator is quite large, the height of the digit is 14mm.
The dimensions of the board are 69x37mm.

The board is assembled neatly, there are traces of flux near the indicator contacts, but in general the board is clean.
The board contains: a reverse polarity protection diode, a 5 Volt stabilizer, a microcontroller, a 470 microfarad 35 Volt capacitor, power elements under a small radiator.
Places for installing additional connectors are also visible, their purpose is not clear.

I sketched a small block diagram, just for a rough understanding of what and how it is switched and how it is connected. The variable resistor is turned on with one foot to 5 volts, the second to the ground. Therefore, it can be safely replaced with a lower denomination. There are no connections to the unsoldered connector in the diagram.

The device uses an 8s003f3p6 microcontroller manufactured by STMicroelectronics. As far as I know, this microcontroller is used in quite a large number different devices such as ammeters.

Power stabilizer 78M05, when operating at the maximum input voltage, heats up, but not very much.

Part of the heat from the power elements is removed to the copper polygons of the board, on the left you can see a large number of transitions from one side of the board to the other, which helps to remove heat.
Also, heat is removed with the help of a small radiator, which is pressed against the power elements from above. This placement of the heatsink seems a little doubtful to me, since the heat is removed through the plastic of the case and such a heatsink does not help much.
There is no paste between the power elements and the radiator, I recommend removing the radiator and smearing it with paste, at least a little but it will get better.

In the power section, an IRLR7843 transistor is used, the channel resistance is 3.3mOhm, the maximum current is 161 Amperes, but maximum voltage only 30 volts, so I would recommend limiting the input at 25-27 volts. When operating at near-maximum currents, there is a slight heating.
A diode is also located nearby, which dampens the current surges from the self-induction of the motor.
STPS1045 10 Amps, 45 Volts is used here. There are no questions about the diode.


First inclusion. It so happened that I carried out the tests even before removing protective film, because in these photos it is still there.
The indicator is contrasting, moderately bright, reads perfectly.

At first I decided to try on small loads and got the first disappointment.
No, I have no complaints about the manufacturer and the store, I just hoped that such a relatively expensive device would have engine speed stabilization.
Alas, this is just an adjustable PWM, the indicator displays% filling from 0 to 100%.
The regulator didn’t even notice the small motor, the day it is a completely ridiculous load current :)

Attentive readers must have paid attention to the cross-section of the wires with which I connected the power to the regulator.
Yes, then I decided to approach the issue more globally and connected a more powerful engine.
Of course, it is noticeably more powerful than the regulator, but at idle its current is about 5 amperes, which made it possible to check the regulator at modes closer to the maximum.
The regulator behaved perfectly, by the way, I forgot to indicate that when turned on, the regulator smoothly increases the PWM filling from zero to the set value, ensuring smooth acceleration, while the indicator immediately shows the set value, and not like on frequency drives, where the real current is displayed.
The regulator did not fail, warmed up a little, but not critical.

Since the regulator is pulsed, I decided, just for fun, to poke around with an oscilloscope and see what happens at the gate of the power transistor in different modes.
The PWM frequency is about 15 kHz and does not change during operation. The engine starts at approximately 10% fill.

Initially, I planned to put the regulator in my old (rather already ancient) power supply for small power tools (more on that some other time). in theory, it should have become instead of the front panel, and the speed controller should have been located on the back, I didn’t plan to put a button (fortunately, when turned on, the device immediately switches to the on mode).
It had to be nice and neat.

But further disappointment awaited me.
1. Although the indicator was a little smaller in size than the front panel insert, it was worse that it did not fit in depth, resting against the racks for connecting the halves of the case.
and if the plastic of the indicator housing could be cut off, then it would not matter, since the regulator board interfered further.
2. But even if I would have solved the first question, there was a second problem, I completely forgot how my power supply was made. The fact is that the regulator breaks the minus supply, and I have a relay for reverse, turning on and forcing the engine to stop, and a control circuit for all this. And with their alteration, everything turned out to be much more difficult :(

If the regulator was with speed stabilization, then I would still get confused and redo the control and reverse circuit, or redo the regulator for switching + power. And so it is possible and I will redo it, but already without enthusiasm and now I don’t know when.
Maybe someone is interested, a photo of the insides of my PSU, it was going to be about 13-15 years ago, almost all the time it worked without problems, once I had to replace the relay.

Summary.
pros
The device is fully functional.
Neat appearance.
Quality build
The kit includes everything you need.

Minuses
Incorrect operation from switching power supplies.
Power transistor without voltage margin
With such a modest functionality, the price is too high (but everything is relative here).

My opinion. If you close your eyes to the price of the device, then in itself it is quite good, and it looks neat and works fine. Yes, there is a problem of not very good noise immunity, I think that it is not difficult to solve it, but it is a little frustrating. In addition, I recommend not to exceed the input voltage above 25-27 Volts.
More frustrating is the fact that I looked quite a lot of options for all kinds of ready-made regulators, but nowhere do they offer a solution with speed stabilization. Perhaps someone will ask why I do this. I will explain how a grinding machine with stabilization fell into the hands, it is much more pleasant to work than usual.

That's all, I hope it was interesting :)

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, it is easy to make such a regulator (you will need to install one transistor). Applicable for adjusting the independent speed of motors in robotics and power supplies. The two most common types of regulators are single-channel and dual-channel.

Video #1. Single channel controller in action. Changes the speed of rotation of the motor shaft by turning the knob of the variable resistor.

Video #2. Increasing the speed of rotation of the motor shaft during the operation of a single-channel regulator. The increase in the number of revolutions from the minimum to the maximum value when the variable resistor knob is rotated.

Video number 3. Dual channel controller in action. Independent setting of the speed of rotation of the motor shafts based on tuning resistors.

Video number 4. The voltage at the output of the regulator is measured with a digital multimeter. The resulting value is equal to the battery voltage, from which 0.6 volts have been subtracted (the difference occurs 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 a single-channel (photo. 1) and two-channel (photo. 2) regulators does not exceed 1.5 A. Therefore, to increase the load capacity, the KT815A transistor is replaced with a KT972A transistor. The pin numbering for these transistors is the same (e-k-b). But the KT972A model is operable with currents up to 4A.

Single channel motor controller

The device controls one motor, powered by a 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 connecting the motor (No. 4) and battery input (No. 5).

Note 1. Screw terminals are not required. With the help of a thin installation stranded wire, you can connect the motor and power supply directly.

1. Principle of operation

The operating procedure of the motor controller is described by the wiring diagram (Fig. 1). Given the polarity, a constant voltage is applied to the XT1 connector. A light bulb or a motor is connected to the XT2 connector. At the input, a variable resistor R1 is turned on, the rotation of its knob changes the potential at the middle output as opposed to the minus of the battery. Through the current limiter R2, the middle output is connected to the base output of the transistor VT1. In this case, the transistor is connected according to the regular current circuit. The positive potential at the base output is increased by moving up the middle output 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 the transistor VT1. The potential will decrease if the situation is reversed.

Circuit diagram

1. Materials and details

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

Note 2. The variable resistor required for the device can be of any production, it is important to observe the current resistance values ​​\u200b\u200bfor it indicated in table 1.

Note 3. To adjust 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 pattern does not need to be changed, since the pin assignment for both transistors is identical.

1. Assembly process

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

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

The input and output of the terminal blocks-sockets are marked in white. A voltage source is connected to the terminal block through the clip. A fully assembled single-channel regulator is shown in the photo. The power supply (9 volt battery) is connected at the final stage of assembly. Now you can adjust the speed of rotation of the shaft using the motor, for 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 stick this drawing (No. 1) on thick and thin cardboard paper (No. 2). Then, with the help of scissors, a disk (No. 3) is cut out.

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 you can start testing. The single-channel motor controller is ready!

Dual channel motor controller

Used to independently control a pair of motors at the same time. Power is supplied from a voltage in the range 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 trimmers 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 the exit to the 1st motor (No. 4) and for the entrance (No. 5).

Note.1 Installation of screw terminals is optional. With the help of a thin installation stranded wire, you can connect the motor and power supply directly.

1. Principle of operation

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

Note.2. To quickly adjust the speed of rotation of the motors, the tuning resistors are replaced with a mounting wire with variable resistance resistors with the resistance values ​​\u200b\u200bspecified in the diagram.

1. Materials and details

You will need a printed circuit board 30x30 mm in size, made of a sheet of fiberglass laminated on one side with a thickness of 1-1.5 mm. Table 2 lists the radio components.

1. Assembly process

After downloading the archive file located at the end of the article, you need to unzip it and print it. A drawing of a regulator for thermal transfer (termo2 file) is printed on glossy paper, and an 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. Holes are formed on the installation drawing in the seats. The assembly drawing is attached to the printed circuit board with dry glue, while the holes must match. The pinout of the KT815 transistor is being made. To check, temporarily connect inputs 1 and 2 with a mounting wire.

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

The motors must be connected to two terminal blocks, and the desired speed must also be set. After successful tests, 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!

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

A simple solution for your task!

Are available

Buy in bulk

The module is built on the basis of a powerful power switch IRF2204 with an operating current of up to 210A, and is designed to adjust the brightness of incandescent lamps, LED strips and frequency of rotation of electric motors with a voltage of 6-30V.

It will be useful for adjusting the brightness of daytime running lights and will be indispensable for adjusting the speed of the stove, as well as a speed controller for an inflatable boat with an electric motor.

Adjusting the frequency of PWM control will completely remove the rumble of the motor windings, and the built-in protection will limit the excess of the operating current.

Specifications

Peculiarities

• Compact size
• Wide range of smooth PWM frequency adjustment - 300-10000Hz.
• Wide operating voltage range 6-30V
• Ability to limit the operating current.
• Reverse polarity protection.
• Built around the powerful IRF2204 field key
• The possibility of strengthening the power key is provided.

Additional Information

At a current of more than 5A, a radiator must be installed. At a maximum current of 80A, the radiator area must be at least 600 cm2.

Articles

Contents of delivery

• Module - 1 pc.
• Instruction - 1 pc.

What is required for assembly

• To connect you will need: wire, screwdriver, side cutters.

Preparation for operation

• Connect a 12V incandescent lamp to the OUT terminal.
• Apply 12V power to the IN terminal
• Rotate the variable resistor. When turning, the brightness of the lamp should change.
• Verification completed. Happy operation.

Operating conditions

• Temperature -30C to +50C. Relative humidity 20-80% non-condensing.

Precautionary measures

• Do not exceed the maximum allowable supply voltage of the module.
• Do not exceed the maximum load capacity.
• Failure to comply with these requirements may result in device failure.

Questions and answers

• Good afternoon. Question about MP4511 PWM power regulator 6-35V 80A The task is to assemble an electric scooter and an electric car for a child. To do this, there is a 90 W 24 V 7 A motor for the scooter and a 110 W motor from the stove Gas 15A 12 V and a battery. Please confirm if I understood correctly. this device Will it be enough to control the speed? because on the sites of do-it-yourselfers, everyone orders Chinese controllers, and with the use of this device, no one collects something. Or will something else need to be included in the circuit. I also ask you to inform the cost of delivery to Orenburg, receipt by mail ?! or a transport company to the addressee?! Thank you.
  • Hello Victor! MP4511- a good choice, this module will work with your motor without any additional devices. Regarding delivery: we work with the SPSR service, the cost of delivery to your city is calculated after placing the order.
• is it possible to order 12(24)-60V 80A???
  • Vladimir, unfortunately, we do not have a module with such parameters for sale.
• Hello. To smoothly adjust the speed of a children's electric car, I want to use this device, tell me if it is possible to use an electronic pedal from the priors with it (instead of a tuning resistor). Is there a smaller alternative to this pedal?
  • Hello! I don’t know on what principle the Priora electronic pedal works. If there is a variable resistor with a resistance of 100 ... 500 kOhm, then it will do.
• Good afternoon. I bought the mp4511 80a module. lay half a year without work, and today it was needed. It is necessary to lower the voltage from the battery of the screwdriver from 22 to 18 volts. I connect the battery and at the input of the regulator I see a voltage of 6.7 volts. load is off. I connect a load lamp of 12 volts 5 watts for testing, the output voltage is not more than 2.3 volts. There is no scheme. Where to dig. Can you send the diagram. Regards, Alexey.
  • Check if jumpers are installed. And the quality of the soldering of all components.
• Hello. I want to use this module in the car. In order to use this PWM controller after replacing the bulbs with LEDs (connect to the old resistor 6 ... 12V). Do I need to change the base schema additionally or leave it as it is?
  • The module is not suitable for your task. Because the adjustment is made along the -12V circuit
• Is it possible to connect electrical outboard motor ECO MOTOR PRO NISSAMARAN 36, if so, how to do it. Do I need a shunt, where to get it and how to eliminate the whistle of the motor, if any. Do I need to put a power diode in parallel with the motor and which one is better. Turnovers are regulated from 0?
  • Can. There is no need to install a SHUNTA. Install a jumper in its place. Set the generator PWM frequency to Hi. If residual winding whistle is a problem, try raising the oscillator PWM frequency to 20 kHz. To do this, change the value of the resistor R1 to 510 ohms, R5 to 10 kOhm, R8 to 4.7 kOhm. To facilitate the operation of the power switch, we recommend installing an additional one in parallel, a place is provided on the board and is designated as VT2. Power keys must be installed on a radiator with an area of ​​at least 1000 cm2..jpg
• I received a power regulator, please tell me how to make a radiator if there are two elements through which heat should be removed on the board, and not one, as in the picture, and there is VOLTAGE between them! T, I can’t connect them to one radiator, because it’s short, and two radiators for each won’t work, because the distance between them is 1 mm !!!
  • Elements must be installed on the radiator through a thermally conductive plate. In some cases, the VD2 element, which has two outputs, does not require installation on a radiator. Check if it does not get hot just bend it away from the radiator.
• What kind of heatsink is needed? Maximum current 5A.
  • Sl-01H will be optimal https://site/shop/1920368
• Is there a box for it?
  • There is no special case for the device. A universal case can be found here https://website/shop/cases
• Hello! I wanted to buy PWM 4511 price 1030 delivery 850r. why so expensive? City of Nalchik, Kabardino-Balkarian Republic. Can't send mail?
  • Good afternoon. To send by Russian Post Fill in all the fields in the basket and choose online payment. Only paid orders are delivered by Russian Post. Cash on delivery is not available!
• Good time of the day. Tell me this regulator can be used to adjust the incandescence of nichrome by connecting it to the outputs of the PC power supply. Accidentally bought a frequency regulator, it does not reduce voltage)
  • Can
• Hello, a question about mp4511. I use to adjust the nichrome wire. Powered by computer power supply. I connect minus, + 12v from the output minus to nichrome and the other end of the wire to 5 V of the Power Supply. Everything works but the windings of the PSU transformer squeak. How can this be removed? Just from 5 in the shim does not work. Come like this. Can you change the jumpers somehow?
  • This is not always possible, since it directly depends on the characteristics of the coils of the transformer and the electric motor. However, winding noise can be removed or reduced using the PWM generator frequency control on the module.
• Hello! How to make the fan not whistle when the speed is reduced?
  • This is not always possible, since it directly depends on the characteristics of the transformer and motor windings. Nevertheless, you can try to change the value of the resistor R1 to 510 ohms, R5 to 10 kOhm, R8 to 4.7 kOhm.
• Will this regulator withstand 500 watts and 37 volts
  • 500W will withstand, but the voltage of 37V will be at the possible limit of the linear stabilizer microcircuit. What chip will come across. If the parameter is underestimated, it may burn out.
• Good afternoon! Tell me, is it possible to control this device through the "Arduino nano" analog output 0 - + 5V, through a transistor, to change the polarity and by connecting instead of a potentiometer?
  • In theory, maybe you should try.

Need adjustments constant voltage to power powerful inertial loads most often occurs among owners of cars and other auto-moto equipment. For example, there was a desire to smoothly change the brightness of the interior lighting lamps, side lights, car headlights, or the fan speed control unit of the car air conditioner failed, but there is no replacement.
It is sometimes not possible to fulfill such a desire due to the high current consumption of these devices - if you install transistor voltage regulator, compensation or parametric, a very large power will be released on the regulating transistor, which will require the installation of large radiators or the introduction of forced cooling using a small-sized fan from computer devices.

The way out is the use of pulse-width circuits that control powerful field power transistors MOSFET . These transistors can switch very high currents (up to 160A or more) at a gate voltage of 12 - 15 V. The open transistor resistance is very low, which can significantly reduce power dissipation. Control circuits must provide a voltage difference between the gate and the source of at least 12 ... 15 V, in otherwise the channel resistance increases greatly and the power dissipation increases significantly, which can lead to overheating of the transistor and its failure. For pulse-width automotive low-voltage regulators, specialized microcircuits are produced, for example U 6 080B ... U6084B , L9610, L9611, which contain a node for increasing the output voltage to 25-30 V at a supply voltage of 7-14 V, which allows you to turn on the output transistor according to a common drain circuit so that you can connect a load with a common minus, but it is almost impossible to get them. For most loads that consume current no more than 10A and cannot cause a drop in the on-board voltage, you can use simple circuits without additional booster unit.

The first PWM regulator assembled onlogic K invertersMOS chips. The circuit is a generator of rectangular pulses on two logical elements, in which, due to diodes, the time constant of charge and discharge of the frequency-setting capacitor is separately changed, which allows changing the duty cycle of the output pulses and the value of the effective voltage at the load.

In the circuit, you can use any inverting CMOS elements, for example K176PU2, K561LN1, as well as any AND, OR-NOT elements, for example K561LA7, K561LE5 and the like, grouping their inputs accordingly. The field effect transistor can be any of MOSFET, which can withstand the maximum load current, but it is desirable to use a transistor with as high a maximum current as possible, because. it has less resistance open channel, which reduces power dissipation and allows the use of a smaller radiator area.
The advantage of the PWM controller on the K561LN2 chip - simplicity and accessibility of elements,
limitations- the output voltage variation range is slightly less than 100% and it is impossible to modify the circuit in order to introduce additional modes, for example, a smooth automatic increase or decrease in the voltage at the load, because regulation is performed by changing the resistance of the variable resistor, and not by changing the level of the control voltage.

Much the best performance the second scheme has, but the number of elements in it is slightly larger.

The effective voltage value at the load is adjusted from 0 to 12 V by changing the voltage at the control input from 8 to 12 V. The voltage adjustment range is almost 100%. The maximum load current is completely determined by the type of power FET and can be very significant. Since the output voltage is proportional to the input control voltage, the circuit can be used as component control systems, for example, systems for maintaining a given temperature, if a heater is used as a load, and a temperature sensor is connected to a simple proportional controller, the output of which is connected to the control input of the device. The described devices are based on an asymmetric multivibrator, but PWM regulator can be built on a waiting multivibrator chip