A few months ago we discovered on the market a particular LCD monitor that could be better than others in terms of electromagnetic emissions. This product, like many other today, has LED backlight, but it is particular because it also has an external power supply and its main electronic board is placed in the base instead of being on the back of the panel. For these reasons this monitor creates less electromagnetic emissions than other monitors. We bought one to try it, but even though the EMF was lower than other monitors, we still felt too harmed by it. The comparison of this monitor with our modified LCD monitor was still totally in favour of the latter.
This monitor has an external power supply that can be replaced. The original power supply is, as usual, a small switching power adapter, which creates an huge amount of electromagnetic noise. We knew that by replacing the original power supply with a low EMF power supply the electromagnetic emissions of the monitor would have been reduced a lot.
We decided to do this test because this monitor has a good exterior appearance, a good picture quality and an high brightness, it is not expensive, and its power supply can be replaced without breaking anything, so the original warranty on the monitor is maintained. If the result in term of electromagnetic emissions was good enough then this would be a viable solution to the problem of the computer monitor, maybe a better overall solution than our modified monitors.
We have built a linear power supply for this monitor, like the power supply of our modified monitors, and have tried this monitor for some time.
This time, when we turned on the monitor we didn't feel the high frequency EMF that we noticed last time. Clearly this is due to the fact that now the DC power comes from a linear power supply and not by the switching power adapter.
We used this monitor for an entire evening, and the next day we used it for typical day of work at the computer, to write and read text files, and also for editing images and videos.
We didn't feel the typical sensation caused by high frequency EMF exposure, however, after some hours of work, we started to feel the effect of the residual high frequency EMF, an effect that we don't feel when we use our modified LCD + monitor. In addition, the effect was slow to disappear after having used the monitor for some hours.
In conclusion, we think that our modified LCD monitor is still better in terms of electromagnetic radiation.
By replacing the external switching power supply with a linear and filtered power supply the EMF emissions of this monitor have decreased a lot.
Unfortunately, the monitor still has some switching type circuit inside, probably the circuits that convert the input voltage into the voltage required by the LED lights, and probably some EMF comes also by the main electronic board which is unshielded.
We still prefer to work with our completely modified LCD monitor.
Currently we don't know whether this monitor could be improved. Maybe the LED lights can be powered with an external DC voltage, so that the EMF radiation created by the LED's driving circuit can be avoided. To know this we need to dismount the monitor and check its wiring and circuits.
We don't want to do advertisement for products that are not valid in our judgement, so in these pages we don't publish the detailed brand and model of this LCD monitor. If you want to know the brand and model of this monitor please send us an email.
Test of a recent LCD monitor with LED backlight 2012
LCD monitors with LED backlight
LCD monitor with LED backlight and linear power supply 2013