This system will provide a low cost and long lasting replacement for hard to acquire surgical lamp bulbs in the developing world. These instructions explain how to use the replacement bulb system with components and tools included in the kit.
Devices in the developing world that require light bulbs to perform their function are of crucial use in providing medical care. However, a major problem with the use of these devices in the developing world is that once the light bulbs break or burn out, the replacement bulbs are very expensive or difficult to acquire. Thus, many devices that are completely functional otherwise are not being used because they lack working bulbs.
One critical medical device that is afflicted by this problem are surgical lamps used in the operating room. These lights are of critical use to the surgeon in illuminating the area of interest during surgery. The absence of these lights seriously hampers the surgeons' ability to make informed decisions and also restricts the performance of surgeries to intervals in the day when there is sufficient light to illuminate the room.
We have remedied this problem with a replacement bulb system that will allow the user to replace conventional light bulbs in commonly used surgical lamps with a new illumination system composed of Light Emitting Diode (LED) bulbs. LED bulbs are much more efficient than conventional tungsten or halogen bulbs, consume less power, are more rigid (due to the absence of moving parts) and also have a much longer life span. Therefore, the LED illumination system will have much longer lifespan, be less expensive to run, and will not break as easily. The LED illumination system will only need to be installed once, and will not need to be replaced for many years.
In addition, this system is compatible with many different types of lamps, with a variety of different light bulbs. This system utilizes the original light bulb base, so the circuit can be made to be compatible with almost any size and shape of light bulb. The system will work for any lamp that uses between 7 and 24 volts DC.
Step 1: Parts List
1.) A blank PCB board
2.) Thin connection wires
3.) A hammer
4.) Soldering iron
5.) Soldering wire
6.) Krazy Glue
The National Semiconductor LM3404 1.0 Amp Constant Current Buck Regulator is used as the current regulating device. A detailed set of instructions can be found in the data sheet for this device. By following these instructions, the circuit designer can determine the ratings of the external components needed to meet their needs.
Step 2: Creating PCB
Next, place the PCB in a pan of etching solution. Agitate the pan to make the etching process go faster. It is also helpful to heat the solution slightly. Keep the PCB in the solution until all of the copper is removed except for where the circuit design is printed on the board. The etching solution will stain your clothing, so be very careful not to splash it on yourself.
Rinse the printed board thoroughly to remove all fluids.
The printed layout is designed so that two circuits and two LED pads can fit onto one PCB board. Separate these four pieces using a saw.
Trim off any excess board to make the circuit as small as possible. Finally, drill the holes where the components will attach using a very small drill. The locations where you need to drill are shown as small circles on the PCB layout.
We used the ExpressPCB to design this board. Since this circuit uses surface mounted devices, the solder pad design needed to be done for each individual component.
Step 3: Placing Components on PCB Board
Step 4: Attaching LED Bulb and Attachment Wires
Finally, solder two attachment wires to the appropriate holes. These wires attach to the bulb connections, allowing the circuit to be powered.
The circuit is now ready for implementation.
Step 5: Removing Glass From Broken Bulb
Remove the broken bulb from its socket.
Place the broken bulb in the plastic bag (provided) and grasp the bulb from the outside at the base. Be careful not to cut yourself with the glass or hit your fingers with the hammer. Strike the top of the broken surgical lamp bulb with a small hammer. Be careful not to strike the bulb with too much force. The aim is to remove the glass and expose the contacts that originally connected the broken filament to the rest of the bulb.
Step 6: Attaching the Circuit to the Bulb
Heat up the soldering iron by plugging it in. Next, hold the tip of the soldering iron to the end of a piece of solder wire. This will cause the wire to melt. Carefully transfer the melted solder onto the contacts while holding the wires from the circuit in the melted solder. Briefly allow the connection to cool and ensure that the connection is strong enough. You may need to hold to components together using tweezers while you are completing this process.
**Caution: Soldering Iron is very hot, do not burn yourself!
Step 7: Testing the System
Turn on the lamp's power, and ensure that the LED turns on.
Testing for the light intensity of the system can by done using the Lutron LX-103 light meter.