PWM Controller (regulator) DIY Easy
Easy PWM Controller with schematic and layout
Schematic with a little theory of PWM and 555
Yep. Schematic with layout, but spiced with some informations about what the PWM controller is all about. In simple , PWM is fast switching the supply on and off and by altering the relative on to off times (duty cycles) the average voltage as have been “considered” from the device which soaks electricity as something in between. Lets assume that we need a 12V supply for some device, when the duty cicle ratio is 50% then device will “consider” it as 6V, so when the duty cycle is 75% the device “consider” it as 9V. Obviously 100% output is by having the output on all the time and at 100%. Those type of regulation is pulse width modulation – PWM, and you need a controller for achieve it.
Now why we need PWM controlling at all? The problems with linear voltage controllers-regulators is that it makes dissipation on regulator, very much depending on load. That can be a lot of energy wasted and we should have radiators for cooling and we don’t want that hassle. Anyway, the current which flowing trough resistive element dissipate heat proportionally by the voltage drop across regulator and ability of load to “soak” the current (it’s power); or to say that the power dissipated is proportional to the voltage across the active elements multiplied by the current through them.
The schematic on the left show very simple PWM controller with NE555 (or LM555), you can play with element values in some range to achieve proper frequency if you need.
Schematic and layout of PWM controller
If you take a look at the schematic, you can see that 555 is for controlling pulse, and MOSFET on the output which is driven by that pulse providing ability to control more load.
Upward figure is the layout of PWM controller following that main principle of pulse width modulation. It is layout made on Atarado board by the online layout editor and if you got more load, you have to mount MOSFET on radiator for cooling, because dissipation, even much smaller in PWM controlling, still exists.
Lower left figure is bottom side of Atarado Smart’n'Easy PCB but all of that is so easy to make that you can take simple stripboard or rasterboard for your project.
I am not sure, did I put the 250k like it is on layout or 100k like in schematic. I think to 100k is better to achieve duty cycle from near 0 to near 100%, but you always may take a look at spreadsheet and figure what is right value for you.
Schematic STRIPLAY, new online schematic and layout editor shows much more strength in designing the circuits on stripboards, and even on breadboard. This editor, besides, has a schematic editor which corresponds to layout editor all based on SVG vector editing which means that you can zoom your work at incredible scales without losing graphic quality. So you may easily check your connections with magnification. There are lot of additional options which you can use and all nets are colored for easy visual tracking both in schematic editor as well as in layout editor, so there’s no reason not to try it.
PWM controller diy advantages
At first, there’s lot of PWM controllers on the market of various types. But even they can be sophisticated the main question is do we need theirs performance for simply PC fan control, or to drive our LED’s. That depends of how far we have to go. The needs for do it yourselfers is mainly narrowed at simple applications at home, and mostly the simplicity of such device relying on 555 is fair enough.
Among few disadvantages of PWM there is lot of application for it like:
- driving and dimming LED lamps
- fan controlling
- halogen lamps dimming
- controlling HHO generators (yes there’s lot of interest in)
- accumulators charging control
- electric bycicles… and so on.