For a class in school I want to generate an AC signal. The project is modelling a wind turbine. We will probably drive the input using a drill. I'm going to need about 10 models. I am only wanting to show the very basics. The signal then needs to be processed, that bit I can handle. Can someone give me a link to a suitable component to produce the ac voltage on ebay?
thanks
The signal then needs to be processed, that bit I can handle.
Car alternator with the rectifier removed.
using a drill.
ics. The signal then needs to be processed, that bit I can handle.
Don't schools have things like signal generators any more?
-- Halmyre
There are numerous ways to do it, and you most likely won't need to buy anything. Give us a bit more clue about your requirements
NT
What sort of frequency, mark to space ratio and shape? CMOS 555 is hard to beat for simplicity and ease of use.
What? Any cheap electric motor will do then. Or scrap 12v fans extacted from old PC chassis. Then they can get a feel for how much work it is.
The signal then needs to be processed, that bit I can handle.
Draw the waveform you want and it can be done. BTW Daquarta can generate arbitrary waveforms on the PC even when the evaluation as an oscilloscope/spectrum analyser runs out.
An electric motor should work (I think)!
My first guess would be an old bike 'dynamo' - the type that is friction driven from the tyre wall.
On Wednesday, October 24, 2012 2:58:02 PM UTC+1, John Benn wrote: =20
Magnet rotating inside coils? You could make such a thing or a car alternat= or should do it. ISTR that you need the 12V supply to make the rotor coil i= nto a magnet & the ouput is regulated by controlling the rotor voltage. I'm= sure you'll find details on Google, or someone more electrically minded wi= ll advise.
Someone's dad will have a spare alternator in the shed. Guaranteed.
Not blowing on a fan of some sort? The shaft of which has a small magnet attached and couple of coils close to it arranged such that the magnet poles induce a voltage/current in the coil.
Filch ideas from:
The steps go from: the wind turning the blades to ac generator to ac signal to rectifier to battery to inverter to bulb. Its only the generation I need help with. I like this approach
Stepper motor on a small pulley, toothed belt/elastic band and a large driven pulley one with a handle and you are in business. Also educates them how much work it would be to light a even an LED by hand!
stepper motor works a treat. Sorted
nerate an AC signal.
ut using a drill.
asics. The signal then needs to be processed, that bit I can handle.
ltage on ebay?
Hah. Not a sine wave. Armature is specially modified.
using a drill.
ics. The signal then needs to be processed, that bit I can handle.
A 13 amp socket. Obviously
That reminds me of an awful display at our local windfarm visitor centre. (Whitelees). There's a hand cranked bicycle wheel that lights up a number of halogen capsule bulbs (about 60W each at a guess).
When spinning fast (for virtually no effort), you can light up 4 or 5 of these bulbs. What's that supposed to teach?
Tim
Idiots designed the display.
It is incredibly educational to have a fixed bicycle/excercise bike and a dynamo rigged so that it can drive either no load, a fluorescent, small radio or an equivalent brightness incandescent lamp. A 100W lamp is a fair amount of effort to sustain for any length of time. You can keep it all low voltage by appropriate choices of component.
Did it once for an Xmas lecture. Also the hand powered one with an LED. Kids switched unused lights off for at least a fortnight afterwards!
Nothing, unless the wheel controls a switching unit and they admit it.
Lighting 200 watts of electrical bulbs is a reasonably major effort using human musclepower on its own. Now, if they had a switch to connect some halogen bulbs, CFLs and LED lights all with the same light output,
*that* would make a good point.
Not a sine wave, no. 3.
On second thoughts, the diodes that change the Ac to Dc are inside the alternator, so a working alternator wouldn't give you AC.
The diodes get fried if you try to jump-start a car with a flat battery, so that someone's dad will probably have a car alternator with fried diodes in his shed that you can modify to get the AC out.
The PC fan sounds like a good plan. You could stick two together and power one to spin the other. Or it to the back of a PC and run it from the fan in that.
shed that you can modify to get the AC out.
one to spin the other. Or it to the back of a PC and run it from the fan in that.
The only problem being that PC fans are normally turned by DC brushless motors which don't work as generators.
The simplest way to get a reasonably pure AC voltage mechanically is to use an old-fashioned bicycle dynamo, which is actually a single phase AC generator. Try Halfords or your local bike shop. If you want to do some advanced teaching, you can use them to show how the changing impedance of the winding with frequency due to its inductance gives a self regulation effect, assuming the right constant load impedance.
Car alternators can be used to demonstrate multi-phase generation, if you remove the rectifying diodes and feed DC power into the rotor. They are normally 3 phase internally.
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