Polly Pocket boat motor/generator

Can a motor be used as a generator?

Not all of them.

To test it, you can connect a voltmeter across the motor's terminals and spin the shaft (I've done this. You can just spin it by hand albeit a little vigorously). If the voltmeter registers a voltage, it can function as a generator.

As our pointy eared friend pointed out you may need to spin the motor vigorously! Maybe the way to go would be a wind mill with a hair drier for the wind or you could use a few pulleys to increase the motors revolutions in the dam idea!

Thanks, Vulcan for the information that some motors may not work as a generator.

Thanks, Mr. Truman Brain on the suggestion of using a windmill with a hair dryer or pulleys on the generator for the dam.

I appreciate that you both took time to reply.

Michael13

I used to use little dc motors to make generators. It probably won't generate enough juice to light even a small bulb, but if you got a cheap voltage meter and hooked it directly to the wires of the motor, you should see the needle leap three times each time the motor shaft is rotated, assuming that it is the kind of motor you pick up on a hobby shop with two little magnets and three sets of windings inside on the commutator. The current is AC and so the needle will leap above and below zero. If you could find a meter at radioshack that responds to one volt and has zero at the center, you're in tall cotton. The hard part is creating a driving mechanism strong enough to turn the motor based on water behind a model dam. But you didn't ask about that, so I won't talk about that.

Another sure-fire science fair winner: a small speaker such as might be found in a cheap table radio can operate as a microphone. Just solder the wires into a 1/4-inch Motorola plug (the kind on guitar cords) and plug it into a guitar amplifier and listen to the feedback scream.

A bit of lore about the dynamotor--what the dc motor/ac generator used to be called back in the early days of electric-start automobiles--the voltage regulator was developed to convert the ac output into dc power to charge the battery and the ignition switch was developed because if you just stalled out the car the way a lot of cars were shut off early on, the battery would be feeding electricity through the motor and kill the battery overnight. So you needed a switch between the battery and the dynamotor. The dynamotor was also used to start the car. In my youth I had a wonderful car called a King Midget, which was manufactured around Yellow Springs OH by a couple of aircraft mavens out of the kind of structural aluminum they used to make fighters out of. The frame of the car was punched with holes to further lighten the car. In the back was a one-cylinder kohler engine (wisconsin in some) that drove one rear wheel through a two-speed automatic transmission about the size of a toaster and a centrifugal clutch that let the car idle without fear the car would take off without you. It featured a dynamotor--the same motor that started the car served as its generator. Damn I miss that car. You could get 75 miles per gallon with it but its top speed was about 45 miles an hour. Seated two. Sounded like a big lawnmower.

I did the same thing with my kids a few years back. A small DC motor linked by belt to an 8 in. dia. ball bearing wheel on which they had glued some plastic caps at regular intervals. A jug of water and a length of tubing brought the water down on the caps, making the wheel turn and lighting the LED. Put all together with some nice drawing that explained how an electric dam works. The teachers and students were pretty impressed. They won the science fair.... Good luck.

A motor can act as a generator. Its done all the time. To generate a voltage, a conductor has to move through a magnetic field. The faster it moves, the more it can generate. Additional conductors passing through the same magnetic field will generate more voltage. A small toy motor I believe has internal magnets. These magnets will supply the necessary magnetic flux lines that the moving wire needs to cut to induce an electrical current through a load such as an LED. You may try and put the shaft of the motor (if a small Direct current TOY motor) in the chuck of a drill motor and vary the speed of the motor. Connect an LED to the 2 wires coming from the motor. Make sure the polarity of the LED ('+' lead) is connected to the '+' lead of the motor or it won't have a chance of working. Hope this works for you