I Linear generator prototype

[Micheal_Leo]

i want to just test a linear generator with galvanometer , the magnet is N28 and the wire (Cu) is of 0.6mm thikness and 10m long , but galvanometer dont show anthing ,

The core is PLA material (3d printed)

The magnet size if 28mm * 10mm * 5mm

 

[.Scott]

Use a voltmeter (with an open circuit).

 

[Baluncore]

What pole orientation does the magnet have?
How is the wire wound on the core?
What type of galvanometer, with what current range?

The flux through the core must change when the magnet is moved.
Have you considered measuring voltage, since V is proportional to the rate of change of flux.

 

[Micheal_Leo]

Use a voltmeter (with an open circuit).

can i use oscilloscope?

 

[Micheal_Leo]

What pole orientation does the magnet have?
How is the wire wound on the core?
What type of galvanometer, with what current range?

The flux through the core must change when the magnet is moved.
Have you considered measuring voltage, since V is proportional to the rate of change of flux.

the magnet is rectangular in shape so core is also in recatngular

 

[Baluncore]

can i use oscilloscope?

Yes.

the magnet is rectangular in shape so core is also in rectangular

When you slide the magnet through the core, the field does not reverse, so you get no voltage induced.

 

[Micheal_Leo]

Yes.

When you slide the magnet through the core, the field does not reverse, so you get no voltage induced.

so kindly how can i do , i should not use core , just coil and magnet ?

 

[Baluncore]

If the magnet is a bar with N-pole at one end and S-pole at the other, then to test the generator, turn the magnet, end for end, outside the coil, while watching the coil voltage.

 

[Micheal_Leo]

i just did one small experiment ,i think PLA is not good for voltage induced
i test coil and magnet direct


https://www.veed.io/view/5b0fe9d6-a.../tools/video-hosting/video-upload&panel=share

 

[Baluncore]

You might try glueing two magnets together, NS+SN, to make a longer magnet, then drop them together through the one coil.

Alternatively, wind two coils in series on the same former. Wind one forwards and the other backwards. Space the coils apart by the length of the magnet.

 

[.Scott]

With an oscilloscope set to the mV range and to trigger on any dV, rapidly swiping the N or S pole across the outside of (but close to) the windings should cause a trace. If it doesn't, get a powerful magnet (like what is used in hard data storage disks) and try again.

 

[Micheal_Leo]

You might try glueing two magnets together, NS+SN, to make a longer magnet, then drop them together through the one coil.

Alternatively, wind two coils in series on the same former. Wind one forwards and the other backwards. Space the coils apart by the length of the magnet.

Perfectly got it. In linear generator i have seen that on galvanomter i get + and - mv. I would like to consider only positive current and use it for my charging purpose. So how can i do that
Thank you

 

[Micheal_Leo]

With an oscilloscope set to the mV range and to trigger on any dV, rapidly swiping the N or S pole across the outside of (but close to) the windings should cause a trace. If it doesn't, get a powerful magnet (like what is used in hard data storage disks) and try again.

Yes same i did and it is working
Thank you

 

[Baluncore]

I would like to consider only positive current and use it for my charging purpose. So how can i do that

You can use a diode bridge to rectify the current so both the positive and the negative currents flow into the battery in the same direction.
https://en.wikipedia.org/wiki/Diode_bridge

You might consider a voltage doubling circuit, but winding more turns, moving the magnet faster or using a stronger magnet are alternatives.
https://en.wikipedia.org/wiki/Voltage_doubler

What voltage will the battery be charged to ?
What voltage does your generator make ?

 

[Micheal_Leo]

You can use a diode bridge to rectify the current so both the positive and the negative currents flow into the battery in the same direction.
https://en.wikipedia.org/wiki/Diode_bridge

You might consider a voltage doubling circuit, but winding more turns, moving the magnet faster or using a stronger magnet are alternatives.
https://en.wikipedia.org/wiki/Voltage_doubler

What voltage will the battery be charged to ?
What voltage does your generator make ?

i have basically 4 linear generators , two on left two on right
i have selected N28 magnet and 0.65mm Cu wire(5m)
but galvanometer show no current at that stage

Generator video

 

[sophiecentaur]

can i use oscilloscope?

Very much so. Your Galvanometer needs to register a small positive and a small, equal amplitude negative spike as the magnet passes through the middle of the coil. If the needle is slow to react, it may be making a tiny twitch which you may not see. A 'scope will have a much greater bandwidth and should ;pick up much smaller and faster voltage variations.
This sort of experiment is often described in books (and by people who have never tried it) which fail to tell you practical details. For instance, if you let the magnet fall from half way down the coil, there will be only a positive (or negative) peak which a low spec meter could follow. What is the sensitivity of the meter? Are the 100,200,300 markings in mA? You could test the meter with another low voltage sourc. 'Dab' a 1.5V battery across it and see what happens.
PS Have you tried connecting across the G terminal and the black?