He gave me a PWM z Alliexpres regulator, max 60V i 20A

From the beginning of the development of electricity and electronics, there was a need to build control systems that would allow a smooth influence on the power emitted in the receiver. The first regulators built as linear ones introduced huge losses on the control element and while they worked relatively well in low-power devices (eg the speed controller of the tape drive motor in tape recorders), it was problematic for medium and high power devices. This was due to the operation of the power elements in the linear range, much lower losses were ensured by working as a key (i.e. open or fully closed, omitting the transition state). By properly controlling the ratio of the opening time to the closing time, it was possible to smoothly regulate the receiver power with minimal losses in the regulator itself. This is how the now commonly used PWM was born. Pulse-Width Modulation ) or Pulse Width Modulation. PWM was found mainly in DC circuits to control the rotation (power) of DC motors, heaters or the brightness of light bulbs (traditional and LED). The system itself generating the signal for the actuator can be implemented in many ways, be it in discrete technology (single transistors) or based on TTL/CMOS digital circuits or even operational amplifiers or specialized PWM controller circuits. It is also easy to implement on almost any microprocessor/microcontroller. One of the most frequently used systems as a PWM driver, both by amateurs and professionals, is the "immortal" NE555.

I got the described regulator module from a friend who bought a few pieces to regulate the speed of the wiper motors in the car. The module is packed in a bag made of antistatic foil;



It gives the impression of a solid construction, the housing made of aluminum profiles with steel plugs also acts as a heat sink (although not entirely, but more on that later).



As if "included" we get a potentiometer for adjustment with a knob, in the picture below I unscrewed the plug to take a look at the interior.



As I mentioned, the housing is supposed to act as a heat sink and is mechanically adapted to this, however, there is no thermocouple between the power elements and the housing wall;





I don't expect long operation at higher currents... The regulator board is 47x40mm and is double-sided.





In fact, the entire regulator consists of a dozen or so elements and its main element is ... NE555! I took a moment and redrawn the circuit board layout;



2SK3599 transistors were used as executive keys, although the selection of gate resistors raises my doubts ...



The MBR20100 duodiode is used as a pin-quenching diode;



The role of the auxiliary voltage stabilizer for the NE555 is played by the LM317 with slightly unusually selected resistors that determine the output voltage;



The "carrier" frequency of PWM is ~20kHz, which should not give any sound effects when working with inductive loads, the duty cycle can be adjusted from about 2.5% to 98%. Below are some photos showing the minimum, average and maximum settings;










In fact, if I were to buy this regulator, I'd rather build it myself .

Erratum;

Gate resistors are not 10k but 300Ω. Sorry for the mistake.