Homemade Transformer

[Zero999]

Building a resistor is as simple as measuring with tester probes along a copper wire, stopping at desired value and cutting the wire. And that's a resistor! For bigger values, wind the wire on something which does not conduct electricity, but beware: this will increase the inductance.

Who said anything about building a resistor?

He wants to build a transformer, in which case the inductance needs to be at a maximum and the resistance minimum. I was talking about under short circuit conditions, the resistance being too high to allow enough current to trip the breaker but it will still be high enough to cause a fire.

[ipman]

To the comment about making my own resistor and capacitor, I do intend to at some point for the same reasons as this project. Am I going to build every capacitor and resistor I ever use? No. But I do wish to gain deep insight into the electromagnetic principles at play in our everyday devices.

Look at the quote above.

[Frangible]

You might want to get a microwave oven transformer (colloquially known as a MOT) and remove the high voltage secondary.  As stated earlier, these transformers are usually the type with the primary and secondary wound on separate bobbins.  This way there is very little chance that you will mess up the primary. 

You can hack out the secondary using a hacksaw or your favorite rotary tool.  At that point you can wind the secondary with different kinds of wire and experiment with it.  Winding without removing the laminations (which are usually welded together) will be a pain, but getting a MOT should be cheap if not free.

[gregariz]

Thanks for the info, do you have the link for the book? I searched through twelve pages of results after searching "books" on the website http://www.jaycar.com.au/index.asp and found nothing about transformer design.

http://www.jaycar.com.au/productView.asp?ID=BM2440&keywords=coils&form=KEYWORD

[Razrburn]

Sorry to do some grave digging here, but this topic came up in my Google searches, and it seemed to be far from completely answered. I choose to revive it because it's easy to find on Google already and might save some peoples time

I have a vintage outboard that is missing it's lighting coil
It's no longer I production and I've exhausted searching for nos and used all over the web. Short of looking at outboards on every sunken wreck I'm out of options. Outboard sat unused for decades, so I basically have a new vintage outboard, I'm not going to buy a new one 2k USD+, it runs like new. Which leads me to making a lighting coil. I came to this hoping to get information on making a core. I'm not working with anything crazy I'm aiming for no higher than 16vac at 6amps so I can rectify it to DC and filter out any spikes. I might just go with a car alternators regulator for simplicity
I know the best material is laminated electrical steel with the grain going the same way. The part I need is a bit like a curved bar. I know I'd have a difficult time finding the right size laminations to salvage from.
I don't seem to have any options then making my own coil, and laminations cause I doubt a company will make me about ten laminations to my specs.

I'm hoping someone has had a similar delema and found something that worked well for them. If I had more room under the engine cover I'd probably make a generator off the flyweel, but even if I did I'd loose efficiency to additional bearings spinning, and a little more effort to start.

I'll close this off by saying I have a decent amount of electrical experience, I've built circuit boards inside of ospreys and f35 joint strike fighters. I also am not short on tools, I have two oscilloscopes. My favorite being a NASA surplus unit used for the start of the apollo program development. I could waste my time trying to make a homemade core. I'm hoping someone might save me the grief and give me some hints on what might work decent as a substitute, or potential sources, that dont want a kidney.