I am new to the DIY audio.I am starting with my first amp, which is gainclone based on lm-3886.I wanted to know advantages of using toroidal transformer over sheilded EI type transformer.I am a student on budget and need help whether its worth the extra $$ for the toroid?
Also can some suggest good quality filter caps from Panasonic and Nichion as these two brands are easily available in my city.
Also can some suggest good quality filter caps from Panasonic and Nichion as these two brands are easily available in my city.
If rated appropriately the EI type has a lot going for it. I would be happy using one in a Gainclone.
As to the caps, you will be looking at 3300 uf to around 6800 uf for the main reservoir caps at a voltage to suit your supply so realistically you are looking at 63 volt caps.
If you can get these in genuine Panasonic or Nichicon then you won't go far wrong.
As to the caps, you will be looking at 3300 uf to around 6800 uf for the main reservoir caps at a voltage to suit your supply so realistically you are looking at 63 volt caps.
If you can get these in genuine Panasonic or Nichicon then you won't go far wrong.
Thread from 2003 toroid vs EI type
http://www.diyaudio.com/forums/parts/20484-transformer-toroid-vs-e-i.html
And a good article.
http://www.soundstage.com/maxdb/maxdb071998.htm
http://www.diyaudio.com/forums/parts/20484-transformer-toroid-vs-e-i.html
And a good article.
http://www.soundstage.com/maxdb/maxdb071998.htm
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one problem that can happen with any kind of transformer is if it is operated near it's rated power handling capacity then the core material can become saturated at the current peaks. that will cause a much bigger magnetic field outside of the transformer which can induce noise in nearby circuits. avoid this by using a "overspec'ed" transformer - rated for higher power than needed for your application.
also, in the thread RJM1 linked above, there was alot of talk about shielding. a copper shield will do nothing to contain magnetic flux from the transformer. ferrous material is needed for a magnetic shield, like mu-metal. copper shielding will only help with something like transient noise in switchmode power supply or RF.
as for caps, when I use electrolytics I always choose caps rated for 105degrees (centigrade) instead of 85degrees because the 105degree caps will last longer.
-Joel
also, in the thread RJM1 linked above, there was alot of talk about shielding. a copper shield will do nothing to contain magnetic flux from the transformer. ferrous material is needed for a magnetic shield, like mu-metal. copper shielding will only help with something like transient noise in switchmode power supply or RF.
as for caps, when I use electrolytics I always choose caps rated for 105degrees (centigrade) instead of 85degrees because the 105degree caps will last longer.
-Joel
Transformer saturation
“It is important to realize that the saturation problem is a function of the applied voltage and frequency only. It is NOT caused by the amount of current drawn from the secondary winding.”
Understanding Transformers: Characteristics and Limitations
This is why when you rewind a microwave oven transformer you have to add more turns to the primary winding to avoid core saturation at low power levels. At continuous high power levels the voltage drop across the primary winding prevents saturation.
You are right about the copper shield not shielding magnetic fields with an EI transformer, but you can mount the transformer so that the coil sides point up and down so that the escaping magnetic fields go vertically and not into your circuit.
“It is important to realize that the saturation problem is a function of the applied voltage and frequency only. It is NOT caused by the amount of current drawn from the secondary winding.”
Understanding Transformers: Characteristics and Limitations
This is why when you rewind a microwave oven transformer you have to add more turns to the primary winding to avoid core saturation at low power levels. At continuous high power levels the voltage drop across the primary winding prevents saturation.
You are right about the copper shield not shielding magnetic fields with an EI transformer, but you can mount the transformer so that the coil sides point up and down so that the escaping magnetic fields go vertically and not into your circuit.
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