Hi everyone,
Eva thanks for explanation I have try to changed the wire size but use more and the result is positive the drop get lower, but still big 20 %.
if you dont mind to answer my second question here :
What is benefit or lose when we rise the freq of PWM osc let say from 33Khz to 48Khz with same parts ........
Eva thanks for explanation I have try to changed the wire size but use more and the result is positive the drop get lower, but still big 20 %.
if you dont mind to answer my second question here :
What is benefit or lose when we rise the freq of PWM osc let say from 33Khz to 48Khz with same parts ........
I gave you a clear reply 
Try reading again, if you can't find it then you would not understand it anyway 
To nitrate: Yes, skin effect causes instantaneous resistance of the wire to be high at the beginning of each cycle and to progressively drop until it approaches the value of DC resistance after a few microseconds. Losses are higher and less current is transferred during this period, so the less current reversal events per second the better.
But it's not only skin effect, according to some papers and figures that have been posted recently, this increased AC resistance is also dependent on the way the wires are laid out on the core, being the lower leakage inductance solutions also the ones that tend to achieve the lowest AC resistance. I think that this is called proximity effect. You may read the "100khz primary winding" thread on the power supply forum (and please ignore the off-topic content).
Try reading again, if you can't find it then you would not understand it anyway To nitrate: Yes, skin effect causes instantaneous resistance of the wire to be high at the beginning of each cycle and to progressively drop until it approaches the value of DC resistance after a few microseconds. Losses are higher and less current is transferred during this period, so the less current reversal events per second the better.
But it's not only skin effect, according to some papers and figures that have been posted recently, this increased AC resistance is also dependent on the way the wires are laid out on the core, being the lower leakage inductance solutions also the ones that tend to achieve the lowest AC resistance. I think that this is called proximity effect. You may read the "100khz primary winding" thread on the power supply forum (and please ignore the off-topic content).
This thread "100khz primary winding" pretty much asks the same questions as i have to ask. It clears a lot up and makes this thread pretty redundant but just one more thing before i accept the limitations of this technology:-
1. What is the actual limiting factor in how much power one can transfer through a switching transformer ( when increasing the load does not result in any appreciable rise in power transfer).
2. I think i've asked this previously but just to clear up, does the physical size of the core really not have an influence on the amount of power the transformer can transfer? And why?
Thank you all for your patience, like i said at the beginning i really have had NO experience with the ferro-magnetic side of electronics and i still find things a bit mythical around this part of the woods.
Regards
Leigh
1. What is the actual limiting factor in how much power one can transfer through a switching transformer ( when increasing the load does not result in any appreciable rise in power transfer).
2. I think i've asked this previously but just to clear up, does the physical size of the core really not have an influence on the amount of power the transformer can transfer? And why?
Thank you all for your patience, like i said at the beginning i really have had NO experience with the ferro-magnetic side of electronics and i still find things a bit mythical around this part of the woods.
Regards
Leigh
eBay Auction #: 200268309289
These cores are F-material OF-43615-TC from Magnetics inc.
I purchased these cores in a previous auction and wound one 1:4 (4+4 on the primary - each primary consisted of two strands of 14g - 16 total primary windings). In an amp with 6+6 FETs in the supply and two TIP35Cs and two TIP36Cs per channel bridged to 4 ohms, the amp produced ~49v RMS across the 4 ohm dummy load at clipping. The supply was running at 30kHz (measured at pin 10 of the TL594).
This was done only to determine what the supply would do with this core and this winding ratio. The outputs couldn't have survived for long at that power level. There wasn't enough copper to produce this power level continuously (although it may be sufficient for music)
The power supply was regulated to approximately ±49v. It dropped to approximately ±39v at clipping but the input voltage had dropped to 12.6v.
The output was probably slightly less than you required but at least you know what the core can do.
These cores are F-material OF-43615-TC from Magnetics inc.
I purchased these cores in a previous auction and wound one 1:4 (4+4 on the primary - each primary consisted of two strands of 14g - 16 total primary windings). In an amp with 6+6 FETs in the supply and two TIP35Cs and two TIP36Cs per channel bridged to 4 ohms, the amp produced ~49v RMS across the 4 ohm dummy load at clipping. The supply was running at 30kHz (measured at pin 10 of the TL594).
This was done only to determine what the supply would do with this core and this winding ratio. The outputs couldn't have survived for long at that power level. There wasn't enough copper to produce this power level continuously (although it may be sufficient for music)
The power supply was regulated to approximately ±49v. It dropped to approximately ±39v at clipping but the input voltage had dropped to 12.6v.
The output was probably slightly less than you required but at least you know what the core can do.
Hi Perry,
I Calculate that to be about 75W through the core. Just as in my case the core is dropping quite a lot of voltage. I'm gonna try and spend a little time very carefully winding a core to ensure good coupling as this seems to be the key here. Up to now i have wound for even distribution across the core ( looks neat ) but i think i have to wind primary and secondries right along side each other to maximize coupling. Hopefully this tactic will produce better regulation.
Thanks for your report on the lash up amp,
Leigh
I Calculate that to be about 75W through the core. Just as in my case the core is dropping quite a lot of voltage. I'm gonna try and spend a little time very carefully winding a core to ensure good coupling as this seems to be the key here. Up to now i have wound for even distribution across the core ( looks neat ) but i think i have to wind primary and secondries right along side each other to maximize coupling. Hopefully this tactic will produce better regulation.
Thanks for your report on the lash up amp,
Leigh
Rails were +/-39V for each channel with load, but with typical 4V rail losses, resulting in +/-35V output from each side. This translates into +/-70V output because the load is bridged, which correspond to 49V RMS (*.707)
Doubling the strands on each primary to four could make an improvement, particularly because the transformer becomes 2 *4 *4 to 2 * 1 *16 so there would be exactly one pair of secondary turns for each pair of primary turns (PA1-PB1 SA-SB PB2-PA2 SA-SB PA3-PB3 SA-SB PB4-PA4 SA-SB... be creative )
Doubling the strands on each primary to four could make an improvement, particularly because the transformer becomes 2 *4 *4 to 2 * 1 *16 so there would be exactly one pair of secondary turns for each pair of primary turns (PA1-PB1 SA-SB PB2-PA2 SA-SB PA3-PB3 SA-SB PB4-PA4 SA-SB... be creative
)
??????
+/-39V per channel
with loses we can say +/-35v at the output ( 70Vac )
70Vpk-pk / 1.42 = 49.29V rms
49.29 / 2 = 24.64Vdc
24.64 / 4R = 6.16A
24.64 * 6.16A = 150W rms
This must be approx the same as what is being transferred through the transformer is it not? or have i got somthing wrong here??
Leigh
+/-39V per channel
with loses we can say +/-35v at the output ( 70Vac )
70Vpk-pk / 1.42 = 49.29V rms
49.29 / 2 = 24.64Vdc
24.64 / 4R = 6.16A
24.64 * 6.16A = 150W rms
This must be approx the same as what is being transferred through the transformer is it not? or have i got somthing wrong here??
Leigh
Looking at the core on e-bay that was used it seems i have two very similar cores. Don't know what material they are made from but the dimensions are the same. I'll try winding them and see what happens. 600W will be plenty for my application. The wire you used seems slightly thick for this application in terms of skin effect however your obviously having more luck than me. I'm gonna try doubling the thickness of my wire. I wonder if the skin depth chart i'm using is inaccurate. Apparently at 40KHz the thickest wire i can use is .4mm
Leigh
Leigh
Perry,
Was the transformer under PWM control or did you run it up unregulated? If it was unregulated a ten volt drop at 600W is just right for my application and i should be able to produce a regulated supply if i apply PWM control. P.S Forgive yesterdays ramblings about power calculations, i was half asleep all day LOL
Regards
Leigh
Was the transformer under PWM control or did you run it up unregulated? If it was unregulated a ten volt drop at 600W is just right for my application and i should be able to produce a regulated supply if i apply PWM control. P.S Forgive yesterdays ramblings about power calculations, i was half asleep all day LOL
Regards
Leigh
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