LCD monitor with LED backlight and modified power supply 2013

Introduction

We have considered again the possibility of using an LCD monitor with LED backlight and external power supply and replacing the external power supply with a linear power supply designed and built by ourselves.

Last year, in summer 2012, we tried this solution with a particular LCD monitor that not only had LED backlight and external power supply, but also had the main electronic board in the base instead on the back of the panel.

The results of 2012 were still not good enough for us, we still could feel the typical prickling and tingling sensation that is harbinger of more serious symptoms。

However this year we tried another LCD monitor with LED backlight for a few days and we noticed that its electromagnetic emissions were really lower than that of the monitor we tested in 2012.

The monitor we used in 2012 was manufactured in 2010, while the one we have tested this year has been manufactured in September 2012. We suspect that this monitor contains new generation circuit boards, and we have seen that the electronic industries have introduced some new electronic components to reduce the electromagnetic emissions from circuits boards.

We tried this monitor for several days, and we started to have again the persistent symptoms due to electromagnetic radiation, so we turned back to our completely modified monitor.

However we decided that it was worth to try this monitor with a linear power supply in place of its very low quality external power adapter.

So we have designed and built a linear power supply for this monitor, which needs 19 V input with current up to 2。1 A。 We have used the same type of circuit of our other projects, with a toroidal transformer, passive LC filters, and linear voltage regulator。

If the monitor with our power supply had low enough electromagnetic emissions we would have finally found a better solution for this problem, since the external power supply can be replaced without altering the monitor at all, so the warranty on the monitor is not lost, and also this solution is much easier to build than our completely modified monitor, and the monitor original brightness is not reduced, etc....

Scheme of this solution
Fig.1 Scheme of this solution
Linear power supply for LCD monitor
Fig.2 Linear power supply for LCD monitor

Results

We have tried the LCD monitor with LED backlight and with external power supply by replacing the original power supply with our linear power supply。 The result is not yet as good as our completely modified monitor。 We still prefer our completely modified monitor, which has also the LED powered directly by the linear power supply, and the electronic board in thick aluminum box and more。

However, we noticed that this monitor with the linear power supply has a little lower emissions respect the the same monitor with its original power adapter.

Let be clear that we haven't checked the EM radiation with instruments, because such low level of EM radiation is quite difficult to measure and compare. This is an impression based on our sensations after using the device for a few days, for typical computer related work or entertainment.

Conclusions

We have tried again the LCD monitor with LED backlight and external power supply and replaced the original very bad quality power supply with a linear power supply. The result is a little better than the system we tried in 2012, probably because the latest LCD monitors contain a new generation of electronic boards. However we still feel the difference respect to our fully modified LCD monitor.

This solution can be useful to who doesn't feel too much harmed by EM radiation but is starting to feel the harm。 This solution is also compatible with workplaces because the monitor doesn't get altered, only the external power adapter is replaced。 For the situations where someone uses the monitor for many hours, but still has many pauses during the day, it could be useful to choose an LCD monitor with LED backlight and external power supply, and replace the external power supply with a linear PSU like ours。

We don't want to mention the brand and model of the particular LCD monitor we have tried, because we don't want to make indirect advertising for any industry of LCD monitors, and that's because all LCD monitors of any brand and model have still lots of electromagnetic emissions. If you want more information about this solution please write us an email.

Related pages

Electromagnetic emissions of LCD-LED monitors
LCD monitor with modified power supply 2012

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