transformers
- Thread starter kpasa
- Start date
martin clark
pinko bodger
Quick summary:
Toroid advantages:
More compact for same power capacity; more efficent magnetic 'cicuit' means lighter weight and a minimum of external field; lower impedance at the same current capacity; slightly lower internal losses; wider frequency response due to coupling efficiency. Disadvantage is ease of 'saturating ' core leading to buzzing and harmonic-generation issues.
E-I core advantages:
Easy to arrange exceptional voltage isolation/ a minimum of capacitance between primary and secondary windings by means of using 'split bobbins'; more tolerant of core saturation effects (due to lower magnetic efficiency) - i.e. less prone to buzzing on noise-ridden mains. This also can be extended to the ability to engineer an optimal magnetic 'gap' to avoid saturation with a standing DC bias current - which is essential to use in many valve output transformers, and why toroids are rarely used here. Ease of custom winding (bobbins are wound before core is interleaved.).
Toroid advantages:
More compact for same power capacity; more efficent magnetic 'cicuit' means lighter weight and a minimum of external field; lower impedance at the same current capacity; slightly lower internal losses; wider frequency response due to coupling efficiency. Disadvantage is ease of 'saturating ' core leading to buzzing and harmonic-generation issues.
E-I core advantages:
Easy to arrange exceptional voltage isolation/ a minimum of capacitance between primary and secondary windings by means of using 'split bobbins'; more tolerant of core saturation effects (due to lower magnetic efficiency) - i.e. less prone to buzzing on noise-ridden mains. This also can be extended to the ability to engineer an optimal magnetic 'gap' to avoid saturation with a standing DC bias current - which is essential to use in many valve output transformers, and why toroids are rarely used here. Ease of custom winding (bobbins are wound before core is interleaved.).
kasperhauser
pfm Member
Which sort was Optimus Prime?
cubastreet
Espresso Fiend
I want to know more, please elaborate
lostintheozone
Cabin Boy
its anorak time
When Transformers are mass produced , they wind them , then they force the bonding material in by using vacuum technology. This is an attempt to bond all the wires together so they dont move. Unfortunately they inevitably have small voids , so some part of the winding is able to move slightly. In operation this is a problem , as when AC is passed , a magnetic field is generated around the wire. Any part of the winding not properly bonded will vibrate as it is repulsed by the field of neighbouring wires (winding) , this movement will generate its own AC voltage , which manifest itself as electrical noise. To make a electrically silent transformer involves hand winding. Place a layer of bonding material on the bobbing and wind the first layer , more bonding material , another layer of winding , until finished , this removes all chance of voids and produces an electrically quiet tranformer. This makes for a quiet power supply and this leads to a better sounding amp, pre amp etc
When Transformers are mass produced , they wind them , then they force the bonding material in by using vacuum technology. This is an attempt to bond all the wires together so they dont move. Unfortunately they inevitably have small voids , so some part of the winding is able to move slightly. In operation this is a problem , as when AC is passed , a magnetic field is generated around the wire. Any part of the winding not properly bonded will vibrate as it is repulsed by the field of neighbouring wires (winding) , this movement will generate its own AC voltage , which manifest itself as electrical noise. To make a electrically silent transformer involves hand winding. Place a layer of bonding material on the bobbing and wind the first layer , more bonding material , another layer of winding , until finished , this removes all chance of voids and produces an electrically quiet tranformer. This makes for a quiet power supply and this leads to a better sounding amp, pre amp etc
Darth Vader
From the Dark Side
Mr Diode,
this is exactly what I helped my dad to do as I kid. In those days we also had T and U laminations.Can't remember the whys and wherefores of these vs E and I.
All our kit was bought from goverment surplus 'radio' shops - they were like Aladdins cave or junk shop as my mom would say. So everything was bespoke modded ex MOD stuff manufactured by the top electronics companies. Hey I still have an unused 19 set!
Nostalgia.
Cheers,
DV
this is exactly what I helped my dad to do as I kid. In those days we also had T and U laminations.Can't remember the whys and wherefores of these vs E and I.
All our kit was bought from goverment surplus 'radio' shops - they were like Aladdins cave or junk shop as my mom would say. So everything was bespoke modded ex MOD stuff manufactured by the top electronics companies. Hey I still have an unused 19 set!
Nostalgia.
Cheers,
DV
PigletsDad
My intelligence test came back negative.
E and I laminations are normally used because they can be punched out of a sheet with less waste than U and T. There is a special shape (known as waste-free), which is very economical - imagine an E and back to front E facing one another. The two bars that are left can be used as the Is.
kasperhauser
pfm Member
hifienthusiast
Vintage by heart
I have read an interview of YBA in the Stereophile magazine that YBA makes their own transformers and pot the transformer in a resin under vacuum.
lostintheozone
Cabin Boy
On the subject of transformers (I'm really thinking about toroids) is it essential to bolt them down - apart from stopping them slipping around in the box? I was just wondering about mounting them more compliantly on foam or similar. This started because I was thinking about the possibility of a stack of toroids in a tube separated and surrounded by a softish material - no great plan here just bike ride musings.
Guy
Guy