I'd like to build a PWM-controlled light circuit. Since I'm not an electrician, I want to avoid working with 230 V as much as possible. I imagined an Arduino (fPWM = 460 Hz) controlling a MOSFET which controls a 12 V LED or halogen light circuit.

However, I want a decent light intensity, so I'd need 60 - 120 W depending on chosen bulbs.

The problem is that when looking for 12 V source, I found out that some of them require certain minimal load (around 10-15 W). I don't know if the frequency of PWM is low enough for the power source to "see" two states or if it could damage the source.

So my question is: do I have to care specially about the power source or will any power adapter work?


For driving 12 Volt LED modules or LED strips, fairly inexpensive and really small / lightweight switching power supplies are available, specifically designed for LED supply. For instance, this one supports 8.1 Amperes at 12 Volts, good for driving up to 90-95 watts of LED strings.

No additional "minimal load" needs to be attached to these power supplies, internal circuitry provides any minimal load needed for stability.

Also, these power supplies are designed to work with a constant load or a PWM switched load, with no special handling required.

Another point to keep in mind is that 60 Watts of LED lighting provides far more light intensity to the eye than a corresponding wattage in incandescent or other conventional lighting technologies. Thus you may not need the wattage you envisage at the moment.

  • \$\begingroup\$ Thanks, I'll try it. I'm just a beginner in this field, thanks for patience. \$\endgroup\$ – Krab Nov 13 '12 at 8:41

I am not sure about theory, but i am using 12v 12A smps bought from market for controlling a larg number of RGB modules. The devices are working fine for last two years. It uses above 18 sources of PWM which are not synchronized. I hope the output capacitors of the adapter solve the issue of load switching. Please note that, when you go for such an adapter, there may be constant current and constant voltage adapters. The constant current adapter may not work for your purpose.


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