DIY

# Do-it-yourself powerful PWM regulator on NE555

Hello everyone, today we will do quite popular and powerful PWM power regulator circuit on the NE555 chip.
I have a video on this topic on the YouTube channel and I will be very grateful if you watch and rate it.
First, let's look at several ways to adjust the power. The very first and most reliable regulator is the linear way of regulation.
An excellent example would be an ordinary variable resistor, the higher the resistance of the resistor, the less current will be at the output. But it has a big drawback, namely the linear mode of operation. All excess stress is converted into heat. Let's say our PSU will have a voltage of 30V, and at the output we will have 12V and as a load there will be a light bulb that will consume a current of 3A. Using an easy formula, you can calculate how many watts of heat will be generated on the resistor.
P = (30-12) * 3 = 53W of heat will be generated on the resistor. At first it seems that this figure is not very large, but in fact it is a huge figure and an ordinary variable resistor will burn out in a matter of seconds. Therefore, we need a powerful resistor that can digest such power, plus there must still be a power reserve. This method is suitable only when there is a small voltage difference between the input and output.
The next way is DC-DC adjustment way. The efficiency of such regulators is already much higher and may even be higher than 90%. We will not delve into the principle of operation of the circuit, but I will say one thing, if you need to regulate the power of powerful lamps and motors, then this method is also not very suitable, as all will be exactly losses on the choke, diode and even on the capacitor.
There is also a third type of power control, namely PWM control. The efficiency of such circuits is already very high, this is due to the fact that only a field-effect transistor with a very small resistance passes the entire load through itself, and this all works in a pulse mode. Attention: the first and second methods are suitable for an adjustable power supply, the third method is categorically unsuitable.
The PWM regulator converts a constant signal into a set of periodic pulses of a certain frequency, in our case, the circuit operates at a frequency of 27 Kilohertz, but everything is exactly when adjusting the duty cycle, the frequency will change slightly in one direction or another, but this should not affect the performance of the circuit and the load itself. The PWM regulator converts a constant signal into a set of periodic pulses of a certain frequency, in our case, the circuit operates at a frequency of 27 kHz, but everything is exactly when adjusting the duty cycle, the frequency will slightly change in one direction or another, but this should not affect the performance of the circuit and the load itself.
If the filling of the shim is 50%, then the light will glow at half its power, and the motor will spin 2 times slower.
The heart of the circuit is the NE555 chip, which is pretty cheap and easy to find. With a 1nf capacitor, we set the operating frequency of the circuit, the lower the capacitor rating, the higher the frequency will be and vice versa, the larger the capacitor rating, the lower our frequency will be.
The circuit also contains a voltage regulator 7812 – it supplies the microcircuit with a stable voltage. I used the Soviet analogue KREN8B, it also stabilizes the voltage around 12V.
And if you do not have a 12V regulator, then in principle any other voltage regulator that stabilizes the voltage from 6 to 18V will do.
A powerful irf2805 field-effect transistor passes the entire load through itself, in principle, any field workers will do. But be aware that if you bought radio parts on Aliexspress then know that the characteristics will differ from the declared parameters.
To begin with, we assemble the power supply unit for the microcircuit itself. There are not many details, just 2 capacitors and 1 roll. We connect the power supply on which it should be set from 13 to 28V, we check if there is a voltage at the output. In my case, it should be about 12V, if everything goes well, then we collect part of the frequency generator.
After we have assembled this part, we take and check the circuit again. If you have an oscilloscope, then there will be no problems, and if you do not have an oscilloscope, then you can use another method. To check, we need a speaker, which we connect to the minus and to the 3rd leg of the microcircuit. You will also need to increase the value of the capacitor by 1nf in parallel, you can connect another one to it, but already at 10nf. When you turn on the circuit, you should hear a squeak, and when you start turning the variable resistor, the search frequency should change. After checking, you can safely solder the power part of the circuit and you can be sure that the regulator will start.
Under heavy loads, the field worker will heat up a little, so it is advisable to screw on a small radiator. But if the load is small, then you don't need to fasten it.
With collector motors, everything goes with a bang too. But note that if you adjust the power of powerful motors, then in addition to the output, it is advisable to solder a protective diode that will burn all the pulsations that come out of the motor on itself.
I also want to say that the voltage after the PWM regulator does not change, it is constant if the input is 15V then the output will be 15V only it will pulsate. Measuring devices take this as voltage regulation, but in fact it is not, and I can prove it to you by showing the photo above.
I really liked this circuit and I advise you to do it too. It starts up the first time and does not require any adjustments. And that's all, I hope you enjoyed my article, I also remind you that at the beginning there is a link to my video, do not forget to watch this important, bye everyone.

Source:

usamodelkina.ru

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