part 2. The toy motor to generator project.?

Question

i asked a question regarding converting a toy motor into a generator. turns out it can happen and i got 10 volts AC from it. next question is this single phase and what would i need to charge up a 1.5 volt battery

Answer 1

Are you sure that it is ac? That seems unlikely. I presume it's a motor with a permanent magnet.

The quick arrangement for something like a NiCd cell would be a diode in series with a resistor. The diode stops the battery discharging through the generator when it is not being driven and the resistor chosen to limit the charging current to a suitable value.

Answer 2

The DC motor generator you have created should be outputting DC not AC. The commutator within the motor is switching the polarity of the generated voltage as the shaft of the motor /generator revolves. The voltage you are producing with a typical toy permanent 1.5VDC motor is single phase.

If you look at the output with an oscilloscope you should see a wave form identical to that of a full wave bridge rectifier. Because this pulsating DC ouput is unfiltered you can measure an AC component with a DVM. Simply putting a filter capacitor (a 25 mfd or larger electrolytic) across the output will remove a great portion of this AC ripple voltage from your generator output.


So far your 10V ouput is without a load . As you draw current from your generator you will most likely have a lower output voltage and you will also increase your load on the primary mover due to back EMF. This loading will also slow your generator down and further depress your voltage output.

You can try charging a set of batteries directly using either filtered or unfiltered DC. The use of a fullwave bridge rectifier will come with a voltage penality of 1.4v lost across the diode junctions. Also the diode will have to be rated to handle the current.

Rather than use a regulator you can alway charge the batteries in series to obtain a high voltage and discharge the batteries in parallel to operate the motor.

If you use a linear voltage regulator you will have a further loss as lenear regulators are inefficient, dumping the extra voltage in the form of heat. If a regulator must be used then consider using a switching regulator which is +90% efficient. (see link , available from digikey for under $10)

Answer 3

All you should have to do is pick up a
bridge at radioshack. to convert it to dc. Then a capacitor to clean up the current coming out. Then buy a 1.6 volt voltage regulator.
You can buy the 1.6 volt regulator at digikey.com or you can buy a "Adjustable-Voltage Regulator" At radio shack but you're going to have to buy all the resistor and capacitors that go along with it to set it to output 1.6 volts.


I'm just guessing at the 1.6 volts but most the time you over charge the voltage on a battery by a little.You're going to have to look it up to see.

Answer 4

If you are getting a.c. from this device the first thing you need is a transformer to convert from 10 to 1.5 volts( I am assuming that this is r.m.s. value) , then you need a rectifier bridge and an R.C. filter to smooth out the wave form.This device seems a little unusual as most of these gizmos are d.c.