Many engineering projects, though not all, require electrical power. For experimental purposes, many information technology (IT) projects require very low quantities of power. Fortunately, there are many reliable and inexpensive sources of electrical power. This page not only reviews many of the sources of power, but also introduces some of the safety issues as well.
Any instruction that involves the power of electricity and electrons must first begin with some consideration of safety issues. With the activities described here, the voltage requirements of the circuits are very low and consequently very safe. Anything more than a few volts and the inexpensive materials used here will generally stop working, such as an LED used as a light. However, any electrical device should be disconnected from its power source when not in use, as it could overheat and come in contact with flammable material that could catch on fire. The real problem comes when learners experiment with more powerful sources of electrical energy. For example, learners of all ages should be reminded that the voltage coming from a house electrical plug is not for play and has 110 volts which can seriously hurt (or worse) anyone who comes in contact with it. That is, some sources of electrons are safe, some are not, and if there is ANY doubt, learners should know to seek adult supervision and permission.
A pair of AA batteries (1.5 volts each) is sufficient for many engineering
projects. However, many other
battery sizes would work. Other web pages will demonstrate these batteries
at work. The pictures below also indicate that devices for measuring electrical
power are very useful. For example, sometimes it is difficult to tell if
the problem with getting something to work is because the light is broken,
the wires are not connected properly, or battery is to weak.
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| Simple battery testers, like the one above, should be used to determine if the batteries are good or have lost their power. | |
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| Click images for larger view. More sophisticated instruments, such as this multimeter above, should be used for determining whether or how much power is being produced. The picture on the right shows the meter connected to measure the output of a handheld-size solar panel. | |
The term powerpack refers to the collection of batteries needed for a given circuit design. Sometimes a single battery will do, but more often, more than one battery will be required. The picture below shows how to make a simple powerpack by connecting the batteries with some fastener like masking tape.
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To make a powerpack for many of the projects noted in other web pages, hold one AA battery on top of another so that their negative and positive ends touch. Next, wrap masking tape around the pair to hold them tightly together. This will provide 3 volts. Click image for a larger view. |
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Some projects will require from 4-9 volts. Though taping several batteries in series could be done, using a battery holder provides much better and therefore more reliable contacts for any set of batteries, even just two.
Batteries can be expensive. There are much less expensive sources of power that are interesting to explore. Some sources of power can come right out of the home refrigerator, involving a number of fruits and vegetables. These are called voltaic batteries. These are described at several web sites. These sources of power require a number of food parts (e.g., pieces of potato) linked together in series. Here are some of the best sites found at this time:
Just when electronics give leftover and spoiling food a newly enhanced value, the last place in your house for generating economic value takes on a whole new level of importance. Along comes a maturing of the fuel cell research with the creation of MFCs that some are calling microbial fuel cells and others are calling micro fuel cells. Using common bacteria found in wastewater treatment plants, Penn State researchers (Logan, February 2004) created an electron flow of useful electricity, for example generating enough electricity to drive a small fan. This MFC process also produces hydrogen and oxygen which then make water. If you also consider that experimental but functioning hydrogen powered cars are currently on the road, this raises an interesting psychological challenge of adjustment. A flush of the toilet could simultaneously make a contribution to your home's reservoir of clean drinking water, a reduction of your electrical light bill, the energy tank of your car and mobile robotic sensors monitoring the needs of your flower garden (Graham-Rowe, 2004). MFCs use bacterial digestion action to pass electrons to the negative electrode of a fuel cell, a point called the anode. A wire connected to the positive electrode produces the current. The first Penn State MFC device was about six inches long and 2.5 inches in diameter.
Even smaller devices have been made from "two carbon electrode threads, each about seven microns in diameter, linked to a cell encased in plastic. Each of the threads is coated with enzymes designed to promote the proper electrode reactions. The cell can generate a maximum of 0.8 volts and 0.6 microwatts of power, adequate to run a low-power silicon chip" (Goebel, 2004). Such devices could be used to power implants under the skin dispensing heart or diabetic medication.
Other well established sources of continuous electricity are available but may involve higher levels of electrical power that require more concern about safety. This would include the use solar panels which make electricity from sunlight. However, many smaller solar panels are safe by default because they only generate small amounts of electrical power. Once the solar panel is paid for, the electricity is free as long as the sun is shining. Sometimes the light from room lighting fixtures will be enough to provide sufficient solar power to light an LED.
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| The above pictures are examples of handheld-size solar panels. The image on the right is an example of an LED connected by the alligator clips to the solar panel. This might be done for the purpose of testing the LED before it was put in a circuit. Naturally, there would have to be sufficient sunshine to enable the solar panel to produce the necessary 3 volts. Click images for larger views. | |
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| Though they do not generate as much power as the highly breakable ceramic solar panels, flexible, almost unbreakable solar panels, can be found. This product is sold to owners of boats and RVs (recreational vehicles) to trickle charge their boat and RV batteries as these batteries often sit unused for long periods of time. They can be bent and dropping them will not cause them to break.Click images for larger views. | |
Many other sources of solar power can be found online.
Buying and using power generators that connect to the wind and to
the water in streams will require consultation with an electrician to make
sure that the power being drawn from them has been throttled down to be
safe. Though homemade windmill and water generators may create far less
electricity than commercial designs, their voltage levels could still be
dangerous unless properly qualified and supervised. The more the need for
supervision of more involved and complex projects, the more they should
be reserved for older and more mature students.
Searches of google.com lead to numerous sites with information aabout such generators:
New forms of electrical power will continue to emerge as well:
