Thursday, April 28, 2011
TEST IT
Spin the magnet REALLY fast and the bulb will light dimly. If it doesn't work, try spinning it in a dark room so you don't miss the dim glow. If needed, adjust the position of the magnets so they don't hit or scrape the cardboard. This thing has to spin *fast*, and if the magnets whack the cardboard and slow down, you won't see any light. Spin it faster than eight revs per second. (IF IT DOESN'T WORK, SEE "DEBUGGING")
Once you get it to work, try clamping the point of the nail into the chuck of a hand-crank drill. Spin the magnets fast with the drill and the bulb will light brightly. Don't go too fast or you'll burn out the bulb, or maybe fling magnets all over the room. You can try this with an electric drill as well, although electric drills don't spin as fast.
Note: your generator produces Alternating Current, not Direct Current. The output voltage is about 2 volts max, so there is no electric shock hazard at all.
HOW IT WORKS
All metals contain a movable substance called "electric charge". Even uncharged wires are full of charge! After all, the atoms of the metal are made half of positively-charged protons, and half of negative electrons. Metals are special because their electrons don't stay connected to the metal atoms, instead they constantly fly around inside the metal and form a type of electric "liquid" inside the wires. All wires are full of electric fluid. Modern scientists call this liquid by the name "electron sea" or "electron gas," or the "sea of charge." The fluid charge is movable, and this lets metals be electric conductors. The movable charge-stuff is not invisible, it actually gives metals their silvery shine. The electron gas is like a silvery fluid. Sort of.
Whenever a circle of wire surrounds a magnetic field, and if the magnetic field then changes, a circular "pressure" called Voltage appears. The faster the magnetic field changes, the larger the voltage becomes. This circular voltage trys to force the movable charges inside the wire to rotate around the circle. In other words, moving magnets cause changing magnetic fields which try to create electric currents in closed circles of wire. A moving magnet causes a pumping action. If the circuit is not complete, if there is a break, then the pumping force will cause no charge flow. Instead, a voltage difference will appear at the ends of the wir es. But if the circuit is "complete" or "closed", then the magnet's pumping action can force the electrons of the coil to begin flowing. A moving magnet can create an electric current in a closed circuit. The effect is called Electromagnetic Induction. This is a basic law of physics, and it is used by all coil/magnet electric generators.
Generators don't have just one circle of wire. Suppose that many metal circles surround the moving magnet. Suppose that all the circles are connected in series to form a coil. The small voltage from each circle will add together to give much larger voltage. A coil with 100 turns will have a hundred times more voltage than a one-turn coil.
Now for the light bulb. If we connect the ends of the coil together, then whenever the magnet moves, the metal's charges will move and a large electric current will appear in the coil. What if we instead connect a light bulb between the ends of the coil? A light bulb is really just a piece of wire. The charges of the light bulb's filament will be pushed along. When the charges within the copper wire pass into the thin light bulb filament, their speed greatly increases. When the charges leave the filament and move back into the larger copper wire, they slow down again. Inside the narrow filament, the fast-moving charges heat the metal by a sort of electrical "friction". The metal filament gets so hot that it glows. The moving charges also heat the wires of the generator a bit, but since the generator wires are so much thicker, almost all of the heating takes place in the light bulb filament.
So, just connect a light bulb to a coil of wire, place a short powerful magnet in the coil, then spin the magnet fast. The faster you spin the magnet, the higher the voltage pump-force becomes, and the brighter the light bulb lights up. The more powerful your magnet, the higher the voltage and the brighter the bulb. And the more circles of wire in your coil, the higher the voltage and the brighter the bulb.
Spin the magnet REALLY fast and the bulb will light dimly. If it doesn't work, try spinning it in a dark room so you don't miss the dim glow. If needed, adjust the position of the magnets so they don't hit or scrape the cardboard. This thing has to spin *fast*, and if the magnets whack the cardboard and slow down, you won't see any light. Spin it faster than eight revs per second. (IF IT DOESN'T WORK, SEE "DEBUGGING")
Once you get it to work, try clamping the point of the nail into the chuck of a hand-crank drill. Spin the magnets fast with the drill and the bulb will light brightly. Don't go too fast or you'll burn out the bulb, or maybe fling magnets all over the room. You can try this with an electric drill as well, although electric drills don't spin as fast.
Note: your generator produces Alternating Current, not Direct Current. The output voltage is about 2 volts max, so there is no electric shock hazard at all.
HOW IT WORKS
All metals contain a movable substance called "electric charge". Even uncharged wires are full of charge! After all, the atoms of the metal are made half of positively-charged protons, and half of negative electrons. Metals are special because their electrons don't stay connected to the metal atoms, instead they constantly fly around inside the metal and form a type of electric "liquid" inside the wires. All wires are full of electric fluid. Modern scientists call this liquid by the name "electron sea" or "electron gas," or the "sea of charge." The fluid charge is movable, and this lets metals be electric conductors. The movable charge-stuff is not invisible, it actually gives metals their silvery shine. The electron gas is like a silvery fluid. Sort of.
Whenever a circle of wire surrounds a magnetic field, and if the magnetic field then changes, a circular "pressure" called Voltage appears. The faster the magnetic field changes, the larger the voltage becomes. This circular voltage trys to force the movable charges inside the wire to rotate around the circle. In other words, moving magnets cause changing magnetic fields which try to create electric currents in closed circles of wire. A moving magnet causes a pumping action. If the circuit is not complete, if there is a break, then the pumping force will cause no charge flow. Instead, a voltage difference will appear at the ends of the wir es. But if the circuit is "complete" or "closed", then the magnet's pumping action can force the electrons of the coil to begin flowing. A moving magnet can create an electric current in a closed circuit. The effect is called Electromagnetic Induction. This is a basic law of physics, and it is used by all coil/magnet electric generators.
Generators don't have just one circle of wire. Suppose that many metal circles surround the moving magnet. Suppose that all the circles are connected in series to form a coil. The small voltage from each circle will add together to give much larger voltage. A coil with 100 turns will have a hundred times more voltage than a one-turn coil.
Now for the light bulb. If we connect the ends of the coil together, then whenever the magnet moves, the metal's charges will move and a large electric current will appear in the coil. What if we instead connect a light bulb between the ends of the coil? A light bulb is really just a piece of wire. The charges of the light bulb's filament will be pushed along. When the charges within the copper wire pass into the thin light bulb filament, their speed greatly increases. When the charges leave the filament and move back into the larger copper wire, they slow down again. Inside the narrow filament, the fast-moving charges heat the metal by a sort of electrical "friction". The metal filament gets so hot that it glows. The moving charges also heat the wires of the generator a bit, but since the generator wires are so much thicker, almost all of the heating takes place in the light bulb filament.
So, just connect a light bulb to a coil of wire, place a short powerful magnet in the coil, then spin the magnet fast. The faster you spin the magnet, the higher the voltage pump-force becomes, and the brighter the light bulb lights up. The more powerful your magnet, the higher the voltage and the brighter the bulb. And the more circles of wire in your coil, the higher the voltage and the brighter the bulb.
Thursday, April 7, 2011
dynamo
drawing of generator
NEXT PAGE->
CONSTRUCTION
First make the hollow-ended box. Score the cardboard strip like so:
___________________________________________________________________
| 8cm | 3.5cm | 8cm | 3.2cm | 7.7cm |
| | | | | |
| | | | | |
| | | | | |
|8 | | | | |
|cm | | | | |
| | | | | |
| | | | | |
| | | | | |
| | | | | |
|________________|________|_________________|_______|_______________|
NOTE: this page must be displayed in COURIER FONT, otherwise
these pictures will be wrecked and unreadable. Most browsers
do this automatically.
_____8_________
_|______________ \
|\ 7.7 | \ 3.5
| \3.2 | \
| \_____________|___\
| | 8 |
| | |
| | |
| | | Fold it like this and tape
| | | it securely.
| | |
| | |
| | |
| | |
\ | |
\|__________________|
________________
_|_______________ \
|\ | \
| \ | \ Use the nail to poke a hole
| \______________|___\ perfectly straight through the
| | | center of the box, going through
| | \ / | both sides and all three layers
| | \ / | of cardboard. Then pull the nail
| | \ (hole) | out and use it to widen all the
| | \ / | holes slightly, so when you put
| | O | the nail back through, it will
| | / \ | be a bit loose and able to spin.
| | / \ |
| | / \ | ( You can find the exact center
\ | / \ | by drawing an "X" to the corners
\|___________________| using a ruler. )
At this point you should clamp your four magnets around the nail and give it a spin. This makes sure the box is large enough. The nail and magnets should spin freely. The corners of the magnets should NOT bump the inside of the box as they spin. If the box is a bit too small, start over and make it a little bigger. Either that, or try a thinner nail. (Also, be sure to use the right magnets. Small ones won't work.)
[YES, you can build a plexiglas box instead if you wish. However, don't make it any larger than this. The wire must stay very close to the spinning magnets, so keep the box as small as possible. It should be slightly more than 3 in. wide and slightly more than 1 in. thick.]
Pick the spool of number-30 magnet wire from
_______________ the kit of spools. This is the thinnest.
_|______________ \ Tape one end of the number-30 magnet wire
|\ | \ to the side of the box, then wind all of
| \ | \ the wire onto the box as shown. It's OK
| \_____________|___\ to cover up the nail hole. Pull the taped
| | | end of the wire out, then tape down both
\ | | of the wires so the coil doesn't unwind.
\\ | | You should have about 10cm of wire left
\\\====================| sticking out.
\\\====================/___
|\\====================/ \
-----+-\====================/ \
/ | ==================== \
/ | | | \ Use sandpaper or the edge of a
| \ | | | knife to scrape the thin plastic
| \|__________________| | coating off 2cm of the wire ends.
| Remove every bit of red coating,
so the wire ends are coppery.
(note: the five lines of wire shown above are not real, that's
the 'equals signs' I used to draw with. The real wire can just
be wound up in a big wad in the center of the cardboard box.)
_______________
_|______________ \
|\ | \
| \ | \
| \_____________|___\ Spread the wire away from the
| | | nail hole and tape it in place.
\ | | Stick the nail back through the
\\ | | holes and make sure it can spin.
\\\====================| Take your four magnets, stick
\\\========---=========/___ them face to face in two pairs,
|\\========(\\)========/ \ Then stick the two pairs inside
-----+-\==========(_)=======/ \ the box and on either side of the
/ | ==================== | nail so they grab the nail. Push
/ | | | | them around until they are some-
\ | | | what balanced and even, then spin
\|__________________| | the nail and see if they turn
freely. If you wish, you can
stick 2cm squares of cardboard
between the magnets to straighten
them, and tape the magnets so they
don't move around on the nail.
_____ magnets
|_____| _____________
|_____| |_____________| 2 magnets
=================|| NAIL |_____________|
|_____| ______O______
|_____| |_____________| 2 magnets
|_____________|
SIDE VIEW OF THE
NAIL AND MAGNETS VIEW FROM THE END
TWIST THE WIRES TOGETHER
Make sure that each end of the generator's wires are totally cleared of red plastic coating. If there is a bit of plastic left, it can act as an insulator which turns off your light bulb circuit.
Twist the scraped end of each generator wire securely around the silver tip of each wire from the small light bulb. (If necessary, use a knife to strip more plastic from the ends of the light bulb wires.) One generator wire goes to one light bulb wire, the other generator wire goes to the other light bulb wire, and the two twisted wire connections should not touch together. In the twisted wires, metal must touch metal with no plastic in between.
_______________
_|______________ \
|\ | \
| \ | \
| \_____________|___\
| | |
\ | |
\\ | |
\\\====================|
\\\========---=========/___
|\\========(\\)========/ \
-----+-\==========(_)=======/ \
/ | ==================== |
| | | | |
| \ | | |
| \|__________________| |
| |
\ /
\ twist /
\ {} twist {} /
\ {} {} /
\____/\______ _______/\__/
\_/
( )
( ) tiny
(_) light bulb
Thursday, March 31, 2011
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Heat Sensor
Nov.24, 2010 in New Circuits Leave a Comment
Here is a simple circuit which can be used as a heat sensor. In the following circuit diagram thermistor and 100 Ohms resistance is connected in series and makes a potential devider circuit . If thermistor is of N.T.C (Negative temperature Coefficient ) type then after heating the thermistor its resistance decreases so more current flows through the thermistor and 100 Ohms resistance and we get more voltage at junction of thermistor and resistance. Suppose after heating 110 ohms thermistor its resistance value become 90 Ohms.then according to potential devider circuit the voltage across one resistor equals the ratio of that resistor’s value and the sum of resistances times the voltage across the series combination. This concept is so pervasive it has a name: voltage divider. The input-output relationship for this system, found in this particular case by voltage divider, takes the form of a ratio of the output voltage to the input voltage.
This output voltage is applied to a NPN transistor through a resistance. Emitter voltage is maintain at 4.7 volt with a help of Zener diode.
This voltage we will use as compare voltage. Transistor conducts when base voltage is greater than emitter voltage. Transistor conducts as it gets more than 4.7 base Voltage and circuit is completed through buzzer and it gives Sound.
Heat Sensor Circuit Diagram
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Circuit Easy
Welcome to CIRCUIT EASY schematic design. This site for Electronics Project, Hobbyist and Educationist. Get free Circuit Diagram and make your School Project yourself.
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This circuits uses very few component and gives melody sound. It uses 3 terminal IC UM66 and can be build small enough to be placed inside a greeting card and operated off a single 3V flat button cell.
There is not much to the circuit. The UM66 is connected to its supply and its output fed to a transistor for amplification. Any common speaker can be used or a “flat” piezoelectric tweeter like the one found in alarm wrist watches. If you use the piezo, then it can be connected directly between the output pin 1 and ground pin 3 without the transistor.
The UM66 looks like a transistor with 3 terminals. It is complete miniature tone generator with a tune. Now they come with wide variety of different tunes.
For amplification we have used a NPN transistor which is BC548. Here BC548 makes a common emitter circuit. For limiting the base current we have used a resistance of 220 Ohms so that transistor will not get damaged by excess current.
Circuit Diagram of Musical Bell
PROCEDURE :
1. Draw circuit diagram on ply board and make hole with compass or broader for component pin insertion.
2. Identify emitter base collector of transistor and pin no. of IC UM66
3. Solder all parts according to the circuit. You will need soldering iron, Soldering flux and flexible wire.
4. Make sure all points are well soldered according to the Circuit Diagram and no dry solders. Wrong connection of IC may heat up and get damage.
5. After loading battery power ON the circuit. Now you can check the function of the project.
Thursday, March 24, 2011
Home | Map | Projects | Construction | Soldering | Study | Components | 555 | Symbols | FAQ | Links Electronics Club
Light-sensitive Alarm Project
A kit for this project is available from RSH Electronics.
Download PDF version of this page
The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light.
* The light-sensitivity of the circuit can be adjusted by varying the 100k preset.
* The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset.
Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on continuously an alkaline PP3 9V battery should last about a month, but for longer life (about 6 months) you can use a pack of 6 AA alkaline batteries.
This project uses an edge-triggered 555 monostable circuit.
Parts Required
* resistors: 10k, 47k, 1M ×3
* presets: 100k, 1M
* capacitors: 0.01µF, 0.1µF, 10µF 25V radial
* transistor: BC108 (or equivalent)
* 7555 low-power timer IC
* 8-pin DIL socket for IC
* LDR (light-dependant resistor) type ORP12
* bleeper 9-12V
* on/off switch
* battery clip for 9V PP3
* stripboard 12 rows × 25 holes
Stripboard Layout
Stripboard layout for light-sensitive alarm
Circuit diagram
Circuit diagram for light-sensitive alarm
Click here for RSH Electronics A kit for this project is available from RSH Electronics. If you are new to electronics buying a kit is a good way to be sure you have the correct parts for the project.
Return to Projects page
* Electronics Club Home Page Soldering iron
* Site Map
* Example Projects
* Construction of Projects
* Soldering Guide
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© John Hewes 2010, The Electronics Club, www.kpsec.freeuk.com
Light-sensitive Alarm Project
A kit for this project is available from RSH Electronics.
Download PDF version of this page
The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light.
* The light-sensitivity of the circuit can be adjusted by varying the 100k preset.
* The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset.
Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on continuously an alkaline PP3 9V battery should last about a month, but for longer life (about 6 months) you can use a pack of 6 AA alkaline batteries.
This project uses an edge-triggered 555 monostable circuit.
Parts Required
* resistors: 10k, 47k, 1M ×3
* presets: 100k, 1M
* capacitors: 0.01µF, 0.1µF, 10µF 25V radial
* transistor: BC108 (or equivalent)
* 7555 low-power timer IC
* 8-pin DIL socket for IC
* LDR (light-dependant resistor) type ORP12
* bleeper 9-12V
* on/off switch
* battery clip for 9V PP3
* stripboard 12 rows × 25 holes
Stripboard Layout
Stripboard layout for light-sensitive alarm
Circuit diagram
Circuit diagram for light-sensitive alarm
Click here for RSH Electronics A kit for this project is available from RSH Electronics. If you are new to electronics buying a kit is a good way to be sure you have the correct parts for the project.
Return to Projects page
* Electronics Club Home Page Soldering iron
* Site Map
* Example Projects
* Construction of Projects
* Soldering Guide
* Study Electronics
* Electronic Components
* 555 Timer
* Circuit Symbols
* Frequently Asked Questions
* Links to other Electronics sites
© John Hewes 2010, The Electronics Club, www.kpsec.freeuk.com
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