• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

transformer winding

Status
Not open for further replies.

Dr_Doggy

Well-Known Member
hi, just wonderin if i can wrap wire around a bar magnet , or do i need a doughnut magnet(closed loop) ,, also what kind of losses would I suffer from using cast iron as a core ?
 

Sceadwian

Banned
You don't use a magnets for transformers. Cast iron is probably one of the worst transformer materials you could use, what kind of transformer are you trying to make?
 

Mike_2545

Super Moderator
Its better to buy pre-made transformers, than to attempt to make your own. Unless its for a specialty project and you can't find the specific type you are looking for.
 
Last edited:

crutschow

Well-Known Member
Most Helpful Member
You need a closed magnetic loop for an efficient transformer. You need laminated soft magnetic steel for transformers up through the audio range and generally some type of ferrite material for frequencies above that. Any form of solid iron or steel for a core will give high eddy current loses in the transformer, which will generate heat.
 

tcmtech

Banned
Most Helpful Member
DO you have a particular need for one that you wna to build or is this a just for fun learning project?

If your just looking to experiment pick up some old battery chargers or microwave ovens. They are the simplest and easiest transformers to rewind and many have the primary and secondary windings side by side.
For HF rewinds the small toroid inductors from the line filters can work rather well with very little work involved in rewinding one of them. Or the ones you can find in most electronic devices can be reworked too!

But for application specific there are many variables that have to be acounted for before one can be hand built.
 

Dr_Doggy

Well-Known Member
lol, ya , i luv these flybacks, but its too big(volume), all i really want is the 2ndry coil and the core, but the blodys all glued together, so i can get the secondary out ok, but i keep shatterin the core, ,, i wanna actually set a few up in series on the same core, and form my own primary loop.


In another expirment i had a 57khz flyback(running off a 2n3055 + sine generator) , when i took the leads from the primary coil , and put them on the feedback loop , the resonant frequency went up to 420khz , and my voltage potential trippled, this also cut my current draw from 0.50 A (which is typical for flybackdriver circuit) to 0.08A, however i need to resort to plan b since im haveing problems with a 5-9v clock ringing that fast (iv used 555 timers and hex inverter clks)
 

Dr_Doggy

Well-Known Member
what about a car ignition coil, i just took one of em apart and its core was composed of straight metal plates!?!
 

Sceadwian

Banned
Are you sure that's an ignition coil? This is how 'normal' ignition coils typically look.
 

crutschow

Well-Known Member
Most Helpful Member
The laminated soft iron core does look like a stack of straight metal plates.
 

Dr_Doggy

Well-Known Member
thats the one!

ya thats it alright , but heres a pic of the core i extracted, to me they look like 1mm thick stainless steel rods, all stacked together, but again , doesnt the core need to be in a loop?
 

Attachments

Sceadwian

Banned
The core of an ignition coil is a solenoid (straight) That's why you can pick them up on an AM radio, the magnetic loop isn't closed. Proper manufacturing of a toroid or pot core ignition coil would be prohibitively expensive. You should have had a loop of wire around that coil. Maybe attached to the case itself.
 
Last edited:
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top