A Magic Switch for PC Mods

--Introducing Reed Switches to Personal Computers

By Dr. Michael
March 28, 2002

You are encouraged to make links to this article from your website and tell your friends

The following article is based on years of experience. It is provided as a free service to our customers and visitors. However, Directron.com is not responsible for any damage as a result of following any of this advice.

Copying the contents for commercial purposes is strictly prohibited without Directron.com's written consent. However, you are welcome to distribute these computer support tips free to your friends and associates as long as it's not for commercial purposes and you acknowledge the source. You are permitted and encouraged to create links to this page from your own web site.

Summary

Switches are used in various computer mods to control lights, LEDs, fans, and other devices inside a PC. The most common types of switch are toggle switches and rotary (rheo) switches, which are often mounted in the front of a PC. This article introduces another type of switch - reed switches - to PC mod enthusiasts. I'll demonstrate the use of a reed switch to turn various devices on and off inside a PC by the action of the opening and closing of the front door of a PC case. The main advantages of this switch are: (1) It can be hidden to give a pleasant surprise and cool effect; (2) It can be activated automatically by the action of a moving object; (3) Relatively inexpensive and widely available.

What's a Reed Switch?

A reed switch is a contact switch actuated by a magnet. It?s a relatively new invention. The reed-like contacts are made of magnetic material. They are brought together by the proximity of a magnetic field. There are two types of reed switches. One has only one position and the other has two positions. A diagram below illustrates how the switch with two positions works:

The normally open (NO) position indicates that the switch is normally off (disconnected) without the magnet. The normally close (NC) position indicates that the switch is normally on (connected) without the magnet. We'll show you how to use these two different positions for various functions.

Materials Used in This Mod

Reed switch : This $6.99 as shown below investment will work like magic for you next time you bring your rig to a LAN party. You can easily find bare-wired reed switches at about $1 as show in the right picture below, but you'll have to do the soldering yourself. Reed switches are often used as sensors in security alarms and as a result are widely available from various manufacturers. We choose to use this surface-mountable, pre-wired, & plastic-enclosed model due to its ease of use. Both the sensor and the magnet are hermetically sealed and therefore moisture and dust proof. It is rated at 0.5A (max.) at 20V AC/DC, which is ideal for PC applications. For certain applications, we'll use a small and strong magnet piece instead of the bulky enclosed magnet that came with this reed switch as shown later.

Permanent magnets: The magnet that comes with the reed switch has a plastic enclosure, which makes it too bulky for certain applications. There are several strong, yet small magnets on the market. We choose to use a low-cost and thin one as shown in the right-hand side of the picture below. This magnet is only 3/32" thick. It?s about 1x1/2" in dimension. This small magnet is easy to hide and requires a very small space to mount. Its black color also makes it ideal to work with black cases.

Wired toggle-switch cable set: This toggle switch / cable set as shown below is designed and sold by Directron. It is ideal for connecting the reed switch by simply substituting the toggle switch with the reed switch. It inserts, by Plug-and-Play, one switch between a 12V device and the power supply. Once modified, it makes connecting the reed switch to the power supply and the devices to be controlled without any requirements for wiring.

I cut the toggle switch off and connect the wires to the NO positions of the reed switch as shown below. If you want to keep a toggle switch in your circuit, you can cut only one of the wires connected to the toggle switch.

Once wired, one of the 4-pin plug is connected to the power supply and the other is connected to an IDE Y-cable so that the reed switch can be used to control multiple devices.

Hydraulic case : We'll add some magic to the sliding front cover of this already magic-looking case. This case is available in many colors including beige and silver. We chose a black one for this project. We?ll first add a side rectangular window. We?ll then install a strobe light on the top, a pulsing buzzer, and a 12" cold cathode light inside. We?ll use the sliding door to turn these three devices on and off.

Dragon 1030 case : This ever-popular case also has a front door, which can be used to activate the reed switch. This case is available in many colors including beige, silver, and blue. We chose a jet black one with a side window for this project. We will mount a 12" cold cathode light in the lower portion of the front bezel and a 4" cold cathode light behind the 5.25" drive bays. We?ll use the swinging opening and closing of the door to turn these lights on and off, respectively.

Controlled devices: 12" and 4" Cold cathode fluorescence lamps, buzzer (shown below, left and top-mount strobe light (shown below, right).

The Idea

Here was how the idea of this mod project came about. One of the reasons some people like case with a front door is that the kids could not easily access the drives and the buttons. However, most of the front doors on a PC case do not have a locking mechanism. We thought it would be great if the action of a door opening turns on devices such as lights and buzzers to alert an adult nearby. Of course the potential application of such a device would not be limited to this idea.

The Hydraulic Case Mod

A side rectangular window was opened and mounted on the side panel. Details of this operation are omitted from this article since there are plenty of instructions on how to cut and mount windows already.

Removing the front bezel of a hydraulic case is easy. The bezel is anchored to the case with six metal "grappers," which can be released by force. Use the handle at the bottom of the bezel to pull it out. Picture on the left shows the back of the front bezel.

The arrow indicates an ideal place to place the reed sensor with a double-sided tape provided with the reed switch. I used "NO," Normally Open, position for this application. When the magnet is away from the switch, the switch is open (disconnected). Once mounted the switch wires can be lead inside the case through the hole that's reserved for other wires from the front bezel. There is enough gap between the front of the metal cage and the back of the plastic front bezel to allow the sensor to stay in this position when the front bezel is mounted to the case. The picture below shows the position of the reed switch on the back of the bezel.

The actuator - magnet - is mounted on the back of the sliding door. You can easily remove the sliding door. Move the sliding door near the central position, use one hand to push the edge (any side) of the sliding door toward the bezel and use the other hand to pull the door out. If your hand is big enough, you can do it with one hand.

The picture below shows the back of the sliding door. The bulky, enclosed magnet that came with the reed switch is too big for this location. There is not enough gap between the sliding door and the front bezel. A small magnet is taped to the door using double-sided tape. If you don't want the magnet to be there permanently, Scotch tape would do just fine. The position of the magnet is important. It must match that of the sensor on the back of the front bezel.

Once you have the magnet in position, you can mount the door back to the bezel just as easily as removing it. Place the door near the middle position of the bezel. Align the wheels by a slight up and down movement and then push the door toward the bezel. You should hear a slight click sound when the door is anchored in its position.

Now you can mount the bezel with the sliding door back to the case.

Connecting the reed switch to the power supply and the devices to be controlled is easy through the pre-wired cable set by a simple plug-and-play action. Plug the female connector to the power supply and the male connector to the devices. Using two IDE Y-cables, I connected the reed switch to three devices: one blue 12" cold cathode light, one 12V buzzer, and one top-mounted strobe light. The result?

When the door is in the closed position, these three devices were off. When the door slides down to the lowest position, all three devices are turned on automatically! The light is on. The buzzer went off. The strobe light started emitting flashlights. These actions form a very impressive experience for by-standers.

The 2nd picture above is a "negative" of the first one, which is used to illustrate the light effects of both of the light inside and the light on the top.

It?s difficult to capture the flashing light from the strobe due to timing problems. We made a 5-second movie shot, which records the flashing light and the sound from the buzzer.

Click here to show the movie (You must have a movie player to view). Location for this movie file: http://store.yahoo.com/lib/directron/rimagemovie.mpg

In addition to the above applications, I can also use this reed switch to turn on the side blow fan when the sliding door is in the down position. This application helps minimize the design disadvantage of this case - some people may feel that the front door may restrict the intake air flow from the front of the case when in down position. As a result, the side-blower is on only when the front door is down.

By carefully selecting the positions of the sensor and magnet, I can make those actions to take place in different ways. For instance, if the sensor is placed behind the middle drive bay, and the magnet on the top of the door, the lights and buzzer will be turned on only momentarily as the door slides down and turned off by itself once the door slides all the way down.

Dragon DX01BD / 1030B Case Mod

This popular case is available under many names - Antec, Directron, Chieftec, Chenming, and Uneec. The swinging door is popular for hiding drives with colors not matching that of the case. I am going to mount a reed switch behind this door so that a Neon light will turn on whenever the door is opened.

The front bezel of this case is anchored to the front of the case by six plastic hooks. To open the front bezel, you?ll need to open both side panels, unhook the plastic hooks, and then pull it out. Make sure all hooks are off before pulling using force. You may have to use a flat screw driver to push the hooks on the right hand side since these, especially the middle one, is hard to reach. Improper pulling may result in broken plastic hooks.

Picture below shows the back of the front bezel for the 1030 case. With proper aligning, I was able to place a 12" cold cathode tube behind this front bezel, taking the advantages of the gap between the switche/LEDs and the 3.5" drive bays. The bezel is still mountable to the case. Mounting a cold cathode light in this position is also advantageous since the small amount of heat generated by the light is released outside of the case. The lighting from this position would give some dramatic effects through the front bezel when viewed in the front of the case.

The reed sensor was mounted between the 5.25 and 3.5" drive bays (barely enough space!). It can also be mounted on the back of any of the unused drive bay covers. For this application, I'll use the "NC," Normally Closed position of the reed switch. When the door is closed and the magnet is adjacent to the sensor, the switch is in an open position (off). When the door is open and the magnet away from the sensor, the switch is closed (on).

The following picture shows the back of the case bezel and the door. The magnet is mounted on the back of the door as indicated by the yellow arrow. Again, double-sided tape was used to mount the sensor and the magnet. If desired, you could use black electrical tape to mask the white magnet case.

A 12" green cold cathode tube is mounted vertically between the case and the front bezel. A 4" blue cold cathode tube is mounted behind the 5.25" drive bays. These lamps are connected to the reed switch connectors as described above through one IDE Y-cable.

As shown by the pictures below, both cold cathode lights are turned on when the door is open. When the door is closed, the lights go off. Mission accomplished!

As shown, the 12" cold cathode lamp in the lower portion gives an especially unique and attractive lighting effect. This light effect is different from various viewing angles. The last picture above is taken from a slightly lower angle. The effect from the 4" lamp behind the drive bays is not as dramatic because there is not enough openings there to let the light out.

Conclusions

With proper wiring and installation, a reed switch works well and easily inside or outside a modded PC to control various devices. A reed switch has the following advantages in comparison with the traditional toggle and rotary switches:

(1) It can be hidden from the front view of a computer. (2) It can be turned on and off automatically by the actions of a door, cover, or other moving objects. This effect can be used to add functions to your case mod. For instance, the lights can be used to indicate that you have forgot to close the door! (3) It is more expensive than a simple toggle switch but less expensive than a rotary switch. (4) It is widely available. (5) The result can give a high-impact impression due to the cool and surprise factors. It's great for show rooms and LAN parties.

Other Potential Applications

Besides the examples described above, we can think of the following applications for reed switches in a modded computer:

Use it to turn a drive bay backlight on and off when a door is opened and/or closed.
If the switch is mounted outside of a case with enough wiring, you can turn on the lights or other devices inside of your PC by the actions of the opening/closing of a drawer or door.
If mounted on the side panel of a PC case, a reed switch would be ideal for alarming intrusion. If a light or buzzer is mounted and wired in another room away from where the computer is, this device can be used to alert a person in the other room when a computer cover is opened.
You can also use a reed switch in a case without a door. If mounted correctly, one can use a magnet outside of a case to turn on and off a switch manually by moving the switch around.
One can use the reed switch outside of a case to indicate the movement of a keyboard or joystick.
With enough wiring, you can use a reed switch mounted in the front of your case to control a device that's mounted outside of your PC, for instance, a 12V lamp underneath of your monitor.
If mounted inside a CD-ROM or DVD drive, the opening and closing of the drive tray can be used to turn on and off certain devices.

I am sure that you can come up with many other applications. Your imagination is your only limitation.

Observations and Notes

Magnets do not work well at all through steel sheets. The magnet actuator and the sensor can be separated by plastic or aluminum sheets such as the case bay covers but they do not work well if separated by the steel metal of a case frame. The steel metal acts as a magnet shield.
Choose the position of the sensor behind the front bezel carefully. Allow enough space to allow the bezel to be re-mounted to your case.
The reed switch works on both 5V and 12V devices. Most devices for case mods and all the devices used for this article are 12V.
It's possible to have multiple reed switches in a PC to control multiple devices independently.
Lead the bare wires of the pre-wired cable set through the front case first before connecting the wires to the reed switch since the 4-pin push-thru Molex connectors are too big to go through the cable hole in the case cage.
The orientation of the reed switch we used for this article relative to the magnet does not affect the switching function, making it easier to mount the switch. In other words, you can have the magnet approaching the switch in any four directions of the switch.
Avoid direct contact between the magnets and floppy diskette and hard drives.
Since this project is considered as a case mod instead of system mod, only cases are shown without other essential system components such as drives or motherboards.

Disclaimer

The above article is provided on a reference basis. As always, follow case mod instructions at your own risk. The author or associated company is not responsible for any damage or injury as a result of following these suggestions nor provides any warranty for the accuracy of the information.

(c) Directron.com, All rights reserved

If you find this article useful, please create a link to it from your website or tell a friend about it. If you have any comments or suggestions about this article, please email information@directron.us

Customer Feedback through Yahoo!
	Join our Newsletter

Shipping Policy	Customer Services	Payment Policy
Est. Shipping Cost Time-in-Transit Map FAQ - Shipping Top Reasons for Delays UPS, FedEx, Postal Office Walk-in Sales APO/FPO Shipping International Tracking Orders	Return Rates Store Statistics Customer Satisfaction Account Applications Frequent Errors FAQ-Services FAQ-Tech Support Newsletter Order Status	Credit Card via Phone Purchase Order Prepay, PayPal Resellers Corporate Schools, Government Terms & Conditions Price & Tax FAQ-Payment
Top Brands
Abit, Acer, AMD, Antec, AOpen, Asus, ATI, Biostar, Buffalo, Cooler Master, Corsair, Creative, Dell, D-Link, Enermax, FSP, Gigabyte, Hauppauge, HP, Intel, InWin, Kingston, Lenovo, Lian-Li, Linksys, Lite-On, Logisys, Logitech, Maxtor, Microsoft, MSI, Mushkin, Netgear, OCZ, Seagate, Shuttle, Sony, SuperMicro, ThermalTake, Vantec, ViewSonic, Western Digital, XFX, Zalman.

Have a question about our products, services or technical issues?
Find the answer instantly! Type your question or key words in English: 95% email/ phone questions already have answers on our web site.
Please check the answer online before calling or e-mailing.

Copyright (c) 1997-2009 Directron.com, Inc., Houston, Texas
Buy - Sell - Trade - Build - Repair - Upgrade - Help - Troubleshoot - Shopping
Computers - Laptops - Servers - Hardware - Parts - Software - Peripherals - Services
High Quality - Low Prices - Discount Shop - Large Selection - Free Products - Fast Shipping
Affiliates: Dallas Computer Store - San Antonio Computer Store - K12 Education Computer Systems

My Cart

Tracking

Order Status