Iron Core (1 Viewer)

[gnrlies]

Hi, we have an assignment for Physics where we have to build a transformer and i am trying to find a good iron core to use for it..

Does anybpdy have any suggestions???

I was thinking of buying a cheap transformer from dick smith and then ripping it apart, but i am woried that i will get market down for that...

Anybody ahev any ideas and i will be really greatefull!

 

[Affinity]

Any iron core would do as long as it isn't too thin(recommend 2 cm diameter), if you don't need anything above 60% efficiency. Would be great if you can get laminated ones though. If your school has an industrial arts faculty you might want to talk to the teachers there, they usually know what to do and have the materials.

Don't be lazy with the coils(wind more) and make sure it is done neatly ie, the primary and secondary coils should be parallel!

 

[gnrlies]

should it be done like over the top of each other??

oir should it be spread out??

hang on, look at this pic...

http://users.bigpond.net.au/gnrlies/diagram.gif

 

[Affinity]

keep them closer -> better, compare the fields that's produced by the two ways of winding( think carefully, don't use the simplified description textbook gives). But it would make your job more difficult than spreading them out, because you would have to ensure each layer is "saturated" with coils

You should wind one of the coils on top of the other, again think about the magnetic fields.

If you can, check out induction coil for some inspiration.

 

[Affinity]

Btw use thick wire for the primary coil

 

[gnrlies]

cool

what about the secondary???

and would you recomend using the wire that isn't insulated? (like in the properly made transformers)? or does the insulated wwork just as well?

 

[Affinity]

Those used in proper transformers are insulated (coated with enamel)

Think should use these. Dicksmith sells them, costs about $6-8 a spool. (use to be $4 )

by the way, thick wire for coil with less turns, not neccessarily the primary coil, (I assume you were making a step up one when I posted the last message)

Maybe 0.8 mm and 0.25 mm for the coils again this depends on things

 

[wogboy]

The best idea is to buy a toroid (which is just a donut shaped piece of iron) to use as an iron core in a transformer (toroidal cores are used quite often for small transformers since they're quite efficient for their size) Something like this type from Jaycar should be just fine (they come in varying sizes):

http://www1.jaycar.com.au/productVi...xxx&pageNumber=&priceMin=&priceMax=&SUBCATID=

Wrap some insulated copper wire around one half of the toroid, and wrap another piece of insulated copper wire on the other half. These two coils now are your primary and secondary windings.

In your diagram, method B works more effectively than A (better magnetic linkage between coils), but using a toroid would be better than both.

 

[Affinity]

A torus would be great, better still if you have it in half because the small space in the middle is really annoying when you try to wind the coils around, make sure you take these factors into consideration

 

[gnrlies]

well basically the thing dont have to work at full efficiency.

All ive got to do is to demonstrate how a transformer can step up, or step down a voltage.

i am only going to use a light bulb to show the effect by means of brigtness and will only use a few volts.

some of this equipment may be hard to get is all im worried about

 

[Affinity]

Wire: dicksmith, $14 buy two different thickness wires (unfortunately quite expensive, there should be cheaper sources, but I don't go around much so can't help you there)
core: torus or just one piece of iron.

Primary coil 100+
secondary experiment with it you should need more coils than the theoretical number to acheive desired voltage



idea:
You can also make a transformer with one coil only.
have 3 leads, one connected somewhere in between the two ends(somewhere in the middle of the coil). the two ends will act as one pair and one end with the center lead will act as another. I think this is more efficient in a way, but never tried.

 

[jayz]

Affinity, u should be an econocrat on shopping and a production worker making transformers in dick smith!

(ROFL)

 

[Affinity]

Jayz, you must have some expertise to offer on this topic , why not share it with us.

 

[Ragerunner]

out of topic but didn't want to create a new thread.

since we are in the topic of pracs, where do u buy/get magnets from?

for the prac where you make a simple motor

 

[Affinity]

just use electromagnets, works better. with the only drawback being a drain on power, which I suppose won't affect you much

 

[Lazarus]

Originally posted by Ragerunner
since we are in the topic of pracs, where do u buy/get magnets from?

for the prac where you make a simple motor

There are various wholesale warehouses around... do a few searches on yellowpages.com.au. I'm on the northern beaches and I obtained mine from a place in Warriewood (near me).

You caaan use electromagnets (and they're always funky) but be prepared to go through a lot of batteries.

 

[Affinity]

Just use the transformers/powerpacks at school

 

[gnrlies]

Originally posted by Affinity
Those used in proper transformers are insulated (coated with enamel)

Think should use these. Dicksmith sells them, costs about $6-8 a spool. (use to be $4 )

by the way, thick wire for coil with less turns, not neccessarily the primary coil, (I assume you were making a step up one when I posted the last message)

Maybe 0.8 mm and 0.25 mm for the coils again this depends on things

which one is 0.8 mm???

the primary or secondary??

(and which one is 0.25??)

thjanks heaps, youve been a great help

 

[Affinity]

as a rule of thumb the one with more current -> thicker
so the coil with less turns.
Primary if you are steping up,
Secondary if you are lowering the voltage.

 

[gnrlies]

Where should i wind my primary and secondary coils to get maximum efficiency?

I was thinking of doing on on either side as in on on each side of the bend (see my iron core as below), but i dont know if it would be more efficient to do it right next to each other