Low EMF Computer

" I am still using the prototype which I developed entirely by myself over a year around 1994. It was excruciatingly painful and often debilitating work to work with live digital keyboards and the succession of shielding, filtering and redesign schemes I tried to reduce their emissions."
Bruce McCreary, Guru of Electromagnetic Compliance (EMC), Inventor of the Analog/Passive Matrix keyboard.

This page describes an attempt to make a computer that is tolerable for the electrohypersensitive by reducing electromagnetic emissions There are three sections, moderate, low and ultra low EMF computer setups..

I - Moderate EMF Computer

This was the first feeble attempt at making a computer tolerable. Wires are everywhere, the user is sitting near an LCD monitor, the keyboard and mouse are primitive and the electrical circuits are rudimentary.

The system employs:

- shielding for the computer, keyboard, trackball, LCD monitor and its power supply.

- a modified LCD monitor equipped with an LED backlight

- the LCD monitor is powered by a linear power supply using custom wound toroid transformers.

- a passive filter blocks the monitor noise from emitting onto the power line.

- all of which are placed at a distance from the user.

A tutorial describes in detail how the LCD monitor was modified

*Tutorial LCD/LED Monitor*

A note on the tutorial: No cooling fans are required if it's all engineered properly by optimizing the voltage output of the transformer. The power supply and filter have been improved. Even though all monitors are equipped with LEDs, they are pulsed on and off for dimming, thus producing EMF.

This system is being developed and tuned by an electrical/biomedical
engineer who suffers from Electrosensitivity. Improvements in lower EMF emissions are literally felt. His quest is to be able to comfortably use a computer again. For him, the average computer or laptop is intolerable after just several minutes of use (symptoms include an unbearable heaviness of being (almost like a slow motion electrocution), clinching chest pains, tremors (especially in the forearms), wailing tinnitus) and a headache. Whereas this computer can be used for longer periods and with less symptoms.


A laptop PC (HP L2005 LiveStrong Special Edition) equipped with an AMD processor that runs at a moderate 800 Mhz, is placed twenty feet away from the user. It is heavily shielded inside a heavy duty mu metal case.

LCD Monitor

The laptop drives an external LCD monitor which is a 17" retrofitted with an LED backlight. The switching power supply circuit board has been removed from the chassis and replaced with a custom linear power supply, also remoted 20 ft. Another custom, linear current regulated power supply drives the LEDs. Components within the LCD monitior itself are shielded with mu metal.


The USB keyboard and trackball are shielded internally and externally with mu metal, decreasing EMF exposure. Direct from the factory, the keyboard and trackball caused severe tinnitus, which the shielding improved.. Here is a pic of the mu metal that was placed inside the keyboard. It was a tedious job drilling all of the holes. There is also a sheet of mu metal on the bottom of the keyboard. Keyboard Shield


Instruments used to measure the EMF include

- a "Trifield Meter EX100" meter (to measure magnetic fields),

and a Grundig Mini 300 world band receiver (to measure the strength and tone of the emitted mid frequency RF) - 30kHz to a few mega Hertz.

an Alpha Labs 'RF Field strength Meter' (to measure High Frequency Radio Frequency (RF) pollution). Note that the RF measurements were inconsistent, and further research showed that very little high frequency RF is emitted from a computer when the wireless is disabled. Besides, at close distances the RF meters reads phantom measurements since the antenna is designed to be long distances from the object being measured. Even a high-end Gigahertz Solutions HF59B reads no RF from a laptop computer with the WiFi disabled. Thus the RF results have been omitted.

The meter can be obtained on-line from stores such as LessEmf. For anyone suffering from Electosensitivity such meters are essential to track down offensive sources of electromagnetic pollution.

Link to EMF Safety Products

Three computers are compared with respect to their EMF emissions, from the low EMF customized computer, to the infamous EMF power house DELL XPS/Ultrasharp monitor (2007WFP) which causes immense physical pain after just a few minutes of exposure. Listed are the measurements of EMF emitted from the various components (mouse, keyboard, monitor, etc.). The first computer is the low emission computer described here composed of an HP L2005 laptop with a customized external 17" LCD  monitor, the second is a Dell Dimension E520 desktop (Core 2 6320 1.86 GHz, 2 Gig RAM) with a 17" DCLCD LCD monitor, the third a Dell XPS 410 Desktop (Core 2 6320 1.86 GHz, 2 Gig RAM, NVIDA GeForce Graphics card, sound blaster card) with an 20" Dell Ultrasharp monitor (2007WFP)

RF measurements were taken with the meter standing free, rather being held in hand. The front of the meter is held directly abut to the object being measured. The 'zero' adjust option of the RF meter was used to set the measured ambient value was zero.

For magnetic field measurements the front of the Trifield meter is also held directly against the device being measured with the meter held in the hand. Same goes for the AM radio.

There's no detectable change in the ambient RF or magnetic field in the room, which stays  constant at 0.001 uw/cm2, and 0.2 milli gauss, respectively, whether the computer is on or off. The ambient values vary slightly from day to day, especially the RF readings. These were taken in the morning where less HAM radios are operated in the northern hemisphere.

Results for Low Emission Laptop (running on its battery)

Magnetic Field (milli Gauss):
mouse: Top 0.2, Bottom 0.2
Keyboard: Top 0.2, Bottom 0.2
Video cable: 0.2
Monitor Power cable: 0.2
Monitor: Front 0.2, Back 0.2
Computer: 0.6 max, AC Power Adapter (when used) 0.5
Monitor Power Supply: 4.0

Microwave Band Sound:
mouse: nearly silent fuzz
Keyboard: Mild Tone
Monitor Low Frequency Fuzz fairly strong especially in upper front.

Results for Dell Dimension 520

Magnetic Field (milli gauss):
mouse: Top 0.4, Bottom 1.4
Keyboard: Top 0.2, Bottom 0.2
Monitor cable: 0.5
Monitor: Front 1.5, Back 15
Commputer: Front 3.0, Rear (by Power supply) 50.0

Microwave Band Sound:
mouse: Mild Fuzz
Keyboard: High Pitch Tone, Fuzz
Monitor High Pitch Tone, Fuzz

Results for Dell XPS 410

Magnetic Field (milli gauss):
mouse: Top 1.0, Bottom 1.5
Keyboard: Top 0.6, Bottom 1.8
Monitor cable: 0.8
Monitor: Front 37.0, Back 10.0
Computer: Front 15.0, Rear (by Power supply) 100.0

Microwave Band Sound:
mouse: Mid Pitch Tone, Fuzz
Keyboard: High Pitch Tone, Fuzz
Monitor: Various High Pitch Tones, Fuzz


Developing low emission equipment is an art that requires laborious hours of trial and error. It's as mysterious an occupation as electrosensitivity is an intriguing disease.

Consider that the ambient fields measured at the body of the user (several feet from the computer), using the meters at hand, are nearly indistinguishable whether the computer is on or off. Yet the affects are clearly noticed by the electrosensitive person. This suggests that the fields travel far further than one would expect, and that the electrosensitive person is extremely sensitive.

As for magnetic fields, the Dell XPS computer emits a staggering 100 milli gauss towards the rear, whereas the low emission computer emits at most 1.0 milli gauss. The Dell E520 is in the middle at 50. Also notice the magnetic field emitted by the Dell XPS monitor (2007WFP) at  37 milli gauss in the front, whereas the low emission Samsung is a mild 0.2. The DCLLCD monitor also emits a mild 1.5 at the front.

The conventional mouse also emits significantly more magnetic field, measured at 1.0 on the top and 1.5 milli gauss 4 on the bottom. Whereas the shielded trackball is at a low 0.2.

LCD Monitor is an Enemy

An LCD monitor is most likely the worst offender to the electrosensitive. It has long been known that it contributes to severe tinnitus and other ill feelings.

The first experiment involved replacing the cold cathode tube lamps with LEDs. This offered very little relief.

The next obvious offender was the power supply. After that was remoted, the symptoms were significantly better. Also note that the LEDs were chosen because they are efficient, produce a pure white light, and run on low a voltage. It would have been nearly impossible to run the 750 volts supplied to the cold cathose bulbs over 20 feet!

However, even with the remoted  LCD power supply, a low frequency form of tinnitus still persisted. This was alleviated a little jby shielding the main LCD circuit board inside the monitor with a sheet of mu metal.

The last improvement was the addition of a low pass filter on the power line feeding the main board of the LCD monitor. The filter, placed near the main board, substantially reduced the higher frequencies from traveling back onto the power cable, thus lowering the measured magnetic field on that cable, and noticeably made the computer more tolerable. The LCD monitor is shrouded with two layers of Veilshield, a fine wire mesh which reduces high frequency RF noise. This is where the monitor stands at this point, despite the Radio Frequency noise (measured with the AM radio) which is still being emitted, especially from the front of the monitor.

Video and Monitor Power Cables

The measured fields emitted by the video and monitor power cables are moderate. Noise from the power cable was mitigated with the filter, thus the video cable is the more troublesome.

A higher magnetic field and RF are emitted by the cables   and monitor when the laptop runs from the AC power adapter as opposed to the battery. Thus it may be concluded that noise is transmitted from the computer to the video cable, or is a result of dirty power. Also note that some noise is also transmitted back from the monitor to the power cable.

The video and Ethernet cables make good antennas. They can be replaced with fiber optic cables. Costs of off-the-shelf equipment have been falling so they are now affordable solutions. If you use fiber optic, the first thing to do is throw away the switching power supplies that come with the converters, and replace them with linear supplies.

Linear vs. Switching Power Supplies

The power supply originally equipped with the monitor produces very dirty power. What are suppose to be DC power signals, are spoiled with sinister spikes, or impulses, of noise at about 30 kHz.

The strategy was to build both custom switching and linear power supplies for the monitor and LEDs, then choose the one with the best results.

Linear supplies have the advantage of providing relatively clean power compared to switching supplies. Linear supplies eliminate the impulses at 30k Hz. The downside to linear supplies is the magnetic field at the transformer, which can be minimized by matching the transformer size to the load, and double windings. The magnetic field at the power supply is 4.0 milli gauss (with heavy shielding) which is reduced to 0.2 at a distance of 1 ft. The 60 Hz magnetic field doesn't seem to travel far, so it can be managed if kept at a distance. An advantage to the switching supplies is the very low magnetic field, 0.2 milli gauss shielded. Overall, the comfort level is greater with custom linear power supplies when compared to switching supplies. Linear power supplies have diode bridge rectifiers which do produce noise as they are switched on and off. This noise does find it's way on the house power lines and into the computer. See Home EMF Measurements on how to remediate this noise with shunt capacitors across the diodes.

Low pass filters ineffectively clean up the high frequency noise produced by the switching supplies before the DC power enters the monitor and LEDs. A 60 Hz component is prominent in the LCD power supply, though no such noise is in the power to the LEDs. It is therefore concluded that the 60 Hz noise is generated by the LCD monitor. 60 Hz noise is also prevalent in the power supplied to the laptop computer, so the noise is not singular to the LCDs. A passive low pass filter place between the monitor and power supply sufficiently cleans the 60 Hz noise. The magnetic field on the LCD power line is negligible.

Here is a snapshot of the LCD power (switching supply - AC component only) without any filtering, LCD Power No Filter The overall noise has an amplitude of over 100 milli volts (peak to peak) out of a 5 volt DC power supply. The "halo" or hazy ghost about the noise are the infamous impulses, intrinsic to switching power supplies, which occur every 30k Hz. Next is a shot of the LCD switching power with filtering, LCD Power Filtered The Total amplitude has been reduced to 40 milli volts, and the high frequency noise has been significantly reduced from 40 milli volts down to 10. Here is a pic of the LED power (switching suppy - filtered), LED Power Filtered. There is no 60 Hz noise seen in the LED power. The prevalent high frequency, switching mode noise has an amplitude of 10 milli volts, up to 35 including the "halo" of 30k Hz impulses.

The power produced by the linear supplies is considerably cleaner and better regulated. The 60 Hz noise generated by the monitor is quenched with a passive LC filter, the amplitude which is less than 20 milli volts. This sinister looking waveform is the unfiltered noise emitted by the main board of an LCD monitor. LCD Power The waves are broadcasted as electromagnetic waves. But you don't have to show an electrosensitive person the broad spectrum of the composite wave, and how the 60 Hz wave fiercely dips to a vertical 'V'. Rather, he can feel it. Non-sensistive people may not feel these waves, but they are imputing deleterious biological affects. The mid-band 30k Hz noise, seen as a halo, can cause a myriad of acute affects to electrosensitives. There is also an entire spectrum of higher frequencies not visualized by an oscilloscope.

Much worse are the emissions from a mini projector. Here is a pic of the noise emitted by a Mitsubishi Pocket LED Projector, again using a clean linear power supply: Projector Power Viscous spikes over three volts in amplitude explains why this projector causes severe discomfort to use, and therefore is not an alternative to the LCD monitor. Heavy shielding is hopelessly inadequate for such a bothersome device.


Shielding can result in a fiasco, or in other cases may help. For instance, the shielding on the main board of the LCD monitor was essential to relieve some of the tinnitus. Yet attempts thus far in shielding the entire LCD monitor resulted in a drastic increase in tinnitus. Also shielding the LCD power cable in flexible steel conduit was terribly uncomfortable.

An attempt to shield a mini LED projector was the biggest disaster of all. Endless days spent on fabricating a double layered mu metal shield put me on my back after testing it for eight hours. The tremors were terrible for weeks. The magnetic field and mid-band frequencies were impressively reduced, yet the RF was still significant at the case. It therefore may be deduced that high RF pollution is a major contributor to the ill symptoms. A similar situation exists with the trackball. The mu metal shield reduces the magnetic field, superlatively reduces mid-band noise picked up by an AM radio, but the emitted RF is actually increased.

Here are a few pics of the mu metal case for the projector. It employs 2 layers of 50 mil mu metal. Projector Case Projector Case w/ Fans Projector Case Inside View Projector Case Aperture

Some purport that at least a 6 inch distance between the RF source and the shield is required, otherwise the shield behaves as a radiator. In fact, the inner shield is close to the projector and does induce mid-band frequencies.

Wireless Networks

The worlds love affair with WiFi (and wireless devices in general) is criminal. Not only are  people harming themselves, but they're infringing on the well being of electrosensitives. Use wired Ethernet. If one must use wireless, a suggestion is to shield the antenna of the wireless router, as shown. Such a simple mu metal shield significantly reduces the RF emitted by the router, yet the wireless still works. Wireless Shield

II - Low EMF Computer

We finally move 25 ft away from the laptop, get a ground, make advancements in keyboard, trackball, power supplies and filters. Embrace fiber optics and eliminate long wires..

The system described here only scratches the surface of solving this insurmountable problem - the main issue of which is shielding the viewing face of the monitor. The monitor is so offensive because of the sheer number of current loops required to make the matrix. magnetic field bio effect = I x F x A x N x M

where I = current, F = frequency, A = area, N = number of turns and M = modulation.

Here is a Parts List of items described in this section.

The project begins with a high frequency ground

Some are getting by with a DEll Inspiron N5050. At 25 ft using binoculars it's tolerable for 20 minutes on a good day . Any longer results in strong tinnitus, headache and other unpleasant symptoms.

The Toshiba Satellite C55-B with a celeron processor is relatively mild. It is shown with a grounded DC "junk box" filter, and a RF veil up front.

It's essential to get as much distance as possible by using an USB cabled keyboard and mouse. USB fiber optic converters eliminate long copper cables which act like antennas, but Eli has his fiber optic keyboard and trackball shown below. To get further distance from the laptop try a screen magnifier such as the ones offered by Maxiaids.com. Screen resolutions are also getting higher, increasing emissions. s.

Others manage to find a specific laptop, through trial and error, that is tolerable to some extent. The HP L2005CU LiveStrong laptop is relatively tolerable, but only when the AMD CPU runs at 800 Mhz. At full speed (1.6 GHz) it's brutal because it consumes much more power. Thanks to a Windows power option the CPU can be under-voltaged and limited to 800 Mhz. The magnetic field on this machine is only 1.5 milli gauss. But this unit is aged and sluggish.

Through personal experience the current laptops (equipped with the first gen. Intel i3, i5, and i7 processors) appear to be abominable, including Macbooks (a 17-inch Macbook with an i7 processor is horrendous). Tests show that nearly all of them register over 100 milli gauss just above the keyboard. But the MacBook Pro, with a solid metal body and magnetic field of only 1.5 milli gauss (2 inches from the screen and keyboard), is still a horror to use, at least for this electrosensitive. This is a case where a relatively low magnetic field is deceptively intolerable. Most likely the case is radiating the near fields.

The Dell Venue 11 Pro was evaluated for a while but eventually caused a severe headache, etc. Eli tested it at 25 ft using 10x binoculars, running on the battery. It seems to be more tolerable than average, but it gets much worse when on-line through a modem. The power sipping Atom processor zips through general tasks, the battery is user replaceable, the high definition display is impeccable, and it has a USB 3.0 port to which a wired Ethernet adapter and keyboard/trackball are plugged.

The Ethernet to USB adapter produces quite a bit of EMF noise which finds its way onto the USB cables. Though the Venue feels mildly tolerable for the initial few minutes of exposure it causes extreme tinnitus, headache and chest pains after just a short time. Symptoms are exacerbated by the the modem and on-line connectivity

Beware of the 5v/19.2v AC adapter (version A00) that plugs into the mini USB connector for charging the battery. It's defective and emits common mode noise that gets onto the house wiring. Version A01 is an improvement, but do not use the Venue or any other computer that is plugged into a switching mode power adapter. The dock is too noisy to use, and produces noise on the AC cable as well. The best way to charge the battery is through the mini USB port with a 19v linear power supply.

For a conventional laptop, there are some with ultra low voltage processors. There are still some with user replaceable batteries and without a touchscreen.

Here is a homegrown fiber optic trackball with the microprocessor removed from the housing. It's isolated with fiber optic cable. It produces near zero emissions when stationary, and some noise when the trackball is moved. This trackball is essential for those who suffer from numb hands from a conventional mouse. it also allows user to sit at a distance from a PC without emissions from long copper wires carrying USB.

This Analog/passive matrix keyboard also has no microprocessor in the case and isolated from the microprocessor with 25 feet of fiber optic USB cable. Much thanks to Bruce McCreary for inventing this crucial device, and Richard Conrad for promulgating this version

This is a second generation fiber optic isolated/shielded/filtered trackball with modern technology. It produces near zero emissions, and can be used with a PC at a distance, or even better with a remote PC shielded over 100 ft away

Here's a shielded low RF media player used to play music (mp3) files from a USB drive. The output is stereo fiber optic, input is fiber optic infrared control. the power is filtered. It is intended to be remoted at a distance.
The dell Inspiron 5000 with 10th gen. Intel and solid state drive has a built-in RJ45 Ethernet socket, so a USB/Ethernet converter is not required. The laptop emits relatively weak lower frequency magnetic fields, as measured with the Trifield. But the AM radio picks up strong RF. Most disconcerting are the random/infrequent pulses of microwaves that have been detected in the RF band of the trifield, even with Blutooth off and in airplane mode. It's bio-effects are less guttural due to weaker low frequency fields, but a burning face, and blinding tinnitus and headache set in. The faster USB controller emits RF in the 135 Mhz band, as measured with the MFJ. The 19v switching mode power adapter that's included with the pc emits intense EMF. It should be avoided and only used to charge the battery while away. Here's a 19 V linear power supply. It comprises a toroidal transformer, low noise FET input OP amp, and a MOSFET transistor. This power supply is free of RF. Wiring shown here adapting the linear power supply to the laptop, including a grounded DC filter

III - Ultra Low EMF Computer

We'll hopefully have a shielded projector


This project has shown a way to reduce the emf emissions from a computer to make it more tolerable for those with certain sensitivities. Even though a mediocre gauss meter indicates the near magnetic field is low, the computer (particularly the LCD monitor) still emits offensive EMF (detected by an AM radio), and therefore can be used for only a limited time per day.

The task of building a practical computer that is completely tolerable for the emf sensitive is nearly an impossible feat. Such a system must be designed from the ground up, suppressing the bothersome spectrum of frequencies emitted by the various components. One cannot entirely depend on measurements alone, but must also test a computer for a while and use your subjective response as a guide in finding a relatively compatible computer. Then you must limit your daily use, otherwise risk sensitization - a condition where one gets severe symptoms after just short exposures.

Three computers were compared with respect to their EMF emissions. The evaluation has indicated that the emitted magnetic field (measured near the equipment, with a gauss meter and AM radio) fairly indicates the degree of subjective electrosensitive symptoms. However, offensive fields abound at a distance even though meters are not sensitive enough to detect them. For more information refer to this article on Low EMF Computing



Computer Shield
LCD/LED Monitor
LCD/LED Monitor Package