For the transformers you'll find the informations on the schematic (number of turns, number of windings) and for the inductors you have to find suitable ferrite cores and you can compute the number of turns acording to the folowing formula:
N^2=L/AL
where
L - is your inductance
N - number of turns
AL - is a tipical value taken from the datasheet of the core. [nH/sq turn]
Anyway if you don't know what core you have you can measure and compute the AL value by winding a number of turns on the core and measure its inductance with a LCR meter. (I use to wind 10 - 20 turns. The more turns you use for that the more precision you have in computing AL) Once you have measured that inductance use the above formula to compute the AL.
Ofcourse the tickness of the wire must be chosen acording to the current that flows thru the winding.
N^2=L/AL
where
L - is your inductance
N - number of turns
AL - is a tipical value taken from the datasheet of the core. [nH/sq turn]
Anyway if you don't know what core you have you can measure and compute the AL value by winding a number of turns on the core and measure its inductance with a LCR meter. (I use to wind 10 - 20 turns. The more turns you use for that the more precision you have in computing AL) Once you have measured that inductance use the above formula to compute the AL.
Ofcourse the tickness of the wire must be chosen acording to the current that flows thru the winding.
Just an FYI for anyone wanting to use original parts for T2 and T4 of K6 SMPS.
"T-QSE1" and T-QSE2 anr nor Mfr. part numbers.
"TQSE1" is part nr 486-082594, "TQSE2" is 486-060394. These are custom wound parts ordered by A&L Labs to QSE Inc.
QSE agreed to provide parts of this specification on the following terms:
(This is an email response to my quote inquiry)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hi Adrian,
486-082594
Mosfet Gate Drive Torroidal Transformer
100 - $14.48 ea
250 - $13.14 ea
500 - $12.28 ea
1000 - $11.69 ea
Lead time 8 weeks
***3 pcs would be minimum order of $500.00***
486-060394
100 - $25.23 ea
250 - $22.94 ea
500 - $21.44 ea
1000 - $20.42 ea
Lead time - 8 weeks
***3 pcs would be minimum order of $500.00***
Can I get your company address and fax number?
Thanks
Lori
QSE INC
PO BOX 360
WATSEKA IL 60970
815-432-5281
815-432-6179 F
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Looks like I'll have to start winding...
For T2, I'll have to get some ferrite toroid cores, since all the toroids I have are powdered iron, and that won't work at these frequencies.
Adrian
"T-QSE1" and T-QSE2 anr nor Mfr. part numbers.
"TQSE1" is part nr 486-082594, "TQSE2" is 486-060394. These are custom wound parts ordered by A&L Labs to QSE Inc.
QSE agreed to provide parts of this specification on the following terms:
(This is an email response to my quote inquiry)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hi Adrian,
486-082594
Mosfet Gate Drive Torroidal Transformer
100 - $14.48 ea
250 - $13.14 ea
500 - $12.28 ea
1000 - $11.69 ea
Lead time 8 weeks
***3 pcs would be minimum order of $500.00***
486-060394
100 - $25.23 ea
250 - $22.94 ea
500 - $21.44 ea
1000 - $20.42 ea
Lead time - 8 weeks
***3 pcs would be minimum order of $500.00***
Can I get your company address and fax number?
Thanks
Lori
QSE INC
PO BOX 360
WATSEKA IL 60970
815-432-5281
815-432-6179 F
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Looks like I'll have to start winding...
For T2, I'll have to get some ferrite toroid cores, since all the toroids I have are powdered iron, and that won't work at these frequencies.
Adrian
The guys from A&T labs sell components from that power supply separately.
link to the price list of the k6 power supply
So if you don't wanna wind transformers you can buy them directly from them, due to the fact that those transformers are not so easy to wind and are the most critical components from the power supply. I think that buying those transformers is an option.
82$ may not be the cheapest price but still is not a fortune.
Winding those transfomers is not easy due to insulation problems at the main transformer and leakage inductance + insulation at the gate drive transformers.
I remember that I built once a gate drive tranformer for a high power welding equipment and by mistake I scratched the wire.....
huh.....new year fireworks..... those offline power supply are not kidding when they blow......
So guys.... take care..... and happy winding....🙂
link to the price list of the k6 power supply
So if you don't wanna wind transformers you can buy them directly from them, due to the fact that those transformers are not so easy to wind and are the most critical components from the power supply. I think that buying those transformers is an option.
82$ may not be the cheapest price but still is not a fortune.
Winding those transfomers is not easy due to insulation problems at the main transformer and leakage inductance + insulation at the gate drive transformers.
I remember that I built once a gate drive tranformer for a high power welding equipment and by mistake I scratched the wire.....
huh.....new year fireworks..... those offline power supply are not kidding when they blow......
So guys.... take care..... and happy winding....🙂
I don't understand about T4 core type& What means 28:28CT? And what core needed to make T2 and Coilcraft's current sensor?
Thaks for your replies.
Thaks for your replies.
...And one more thing....in the K6 power supply...
They put a snubber in the primary of T4.... R13 the resistor from the snubber is a 22w resistor....in the picture i see that they mount a wirewound resistor wich is highly inductive.... In this case I am not so sure about the role of that snubber...
As far as I know power resistors for snubbers must be non inductive. I saw some thick film resistors at digikey that are suitable for that job....
TDH35P47R0J-ND
TEH70M47R0JE-ND
The price of the TDH35P47R0J-ND is comparable to the price of the resistor they used. But it may be get hotter than the original one due to the smaller case.
They put a snubber in the primary of T4.... R13 the resistor from the snubber is a 22w resistor....in the picture i see that they mount a wirewound resistor wich is highly inductive.... In this case I am not so sure about the role of that snubber...
As far as I know power resistors for snubbers must be non inductive. I saw some thick film resistors at digikey that are suitable for that job....
TDH35P47R0J-ND
TEH70M47R0JE-ND
The price of the TDH35P47R0J-ND is comparable to the price of the resistor they used. But it may be get hotter than the original one due to the smaller case.
Gyp5y said:
for T4
ETD49 is the core type and 28:28ct means that the primary has 28 turns and the secondary has also 28 turns but is center tapped (14+14 turns)
For T2
a good start is to find a toroidal core with similar dimensions with the original one (not necessarily same dimensions it can be bigger...
I usually build gate drive transformers on any ferrite core that comes in my hand at the time....
In one of my early post in this thread I put two links to pages with valuable guidelines on building gate drive transformers....
and finally about the current transformer
funberry posted the datasheet of the original current transformer...
in that datasheet you have all the information you need to build one.... secondary number of turns, secondary inductance...
you can make yourself an idea of the size of the toroidal core from the outline dimensions presented in the datasheet....
for choosing the core all you need is to compute the AL value (from number of turns and inductance) with the formula I posted early and if you have the AL value and some aproximative dimensions it's easy to find a core for that transformer
As funberry stated in post #60 you better know what you are doing there because building offline power supplies is not as easy as it looks and you need some specific equipments to debug that SMPS if it wont work from the first time (insulation transformer,circuit breaker, oscilloscope, diferential probes) and a LCR meter in order to be able to measure the inductances of the transformers you build. If you dont have those equipments i dont see how you can build the power supply...
Anyway blowing a power supply like this one may not be fun but is definetely spectacular.... as I said .... new years fireworks
cd-i, funberry
I'm just want to build this amplifier. I understand (little) in amplifiers and I really don't know much in such kind of power supplies. (I'm sorry for my level of english). I wanted to build this amplifier with simple power supply (Using torroidal transformer), but I havn't enough money to buy them (I don't say about price for capacitors). This power supply is much cheaper but I have problems with finding original parts in Ukraine. So your replies is very usefull to me.
Thank you very much for your help.
P.S. Sorry again for my english
(Russian and Ukrainian is much simplier to me 🙂 )
I'm just want to build this amplifier. I understand (little) in amplifiers and I really don't know much in such kind of power supplies. (I'm sorry for my level of english). I wanted to build this amplifier with simple power supply (Using torroidal transformer), but I havn't enough money to buy them (I don't say about price for capacitors). This power supply is much cheaper but I have problems with finding original parts in Ukraine. So your replies is very usefull to me.
Thank you very much for your help.P.S. Sorry again for my english
(Russian and Ukrainian is much simplier to me 🙂 )Don't worry. I have a such equipment (I suggest that i can get LCR meter from my friend 🙂 ) And I'll be very carefull, 'cos like I said I really don't know much in such kind of power supplies.
$82 is not an option for me. I cannot spend that kind of money for inductors.
After all, this is a DIY forum, for people who like to make things with their own hands.
I'm not concerned about winding T4; leakage inductance can be minimized with good , tight , symmetrical winding geometry. I may even wind one or all windings with copper tape. I've wound Tesla coils before, which require much more attention to insulation than this thing. And it doesn't have to pass CE logo requirements (most chinese transformers in computer power supplies don't either, even if they're labeled as such).
Obtaining the core for T4 may be a challenge. The ETD platform is probably one of the most expensive core+bobbin combination there is out there. The center post on the '49 is 16mm diameter, so 201 sq. mm. I think you can substiture any core with a center-leg cross sectional area similar to or greater than the ETD49.
If you kow the grade of material it's certainly better than if you don't. The K6 uses an Epcos N87 ferrite (Ferroxcube and Fair-Rite call this a 3C85) which is good from 40 to 400KHz. My rule of thumb is that if I'm going to use a core of unknown material to make an SMPS power transformer, I want a core that has served as an SMPS power transformer before.
T4 needs to be wound with the utmost symmetry. Each winding must span the circumference of the torroid, with turns evenly spaced, not bunched together on one side. Each secondary must be spread out evenly over the primary. Any assymetry here could cuase asymmetric gate drives on the MOSFETS, and a skewed transformer waveform. In worst case, the magnetization curve can be skewed sufficiently in one direction, to cause the core to slowly walk up to saturation, if the (small) dead-time provided is not enough to reset it.
If I have several toroids of unknown material I want to use for T4, I'll test them this way:
Make 2 windings of 10 turns each, insulated hookup wire. With the waveform generator, feed 100Khz square wave (through 20ohm resistor) into one winding. Load the other winding with a 1K pot ( and a 20ohm series res), and monitor waveform with a scope accross the pot. Vary the pot resistance from 1 K towards zero and write down output voltage under different loads. Repeat for all cores I have. Chose the core with the lowest drop on load in the secondary.
Adrian
Daniel,
Nice to hear from you.
I'm almost done building the K6 SMPS.
I have to work backwards, building the PS first, since I need it to test an amp during construction.
Adrian
Nice to hear from you.
I'm almost done building the K6 SMPS.
I have to work backwards, building the PS first, since I need it to test an amp during construction.
Adrian
hello funberry,
nice to hear that the K6 is almost done. Since I intend to build that SMPS too i'm very curios how it works. And one more thing...do you intend to use it "as is" or you intend to do some modifications in the output voltage? Because I intend to power 4 amplifiers of about 150w/ 8ohm from it. Right now i'm building the amp but i don't know it's exact power requirements (quasi's design).
quasi said that it should work at around +/- 50v but I prefer to build the amp first, see how it works and after that build the power supply. Anyway if quasi is right (and i don't see why not) i have to modify the power supply (increase a little the two 36,5k resistors R32 and R28).
Ok, enough talk for today....
I'm looking forward to hear that K6 SMPS is working well...
have a nice week-end
cheers
nice to hear that the K6 is almost done. Since I intend to build that SMPS too i'm very curios how it works. And one more thing...do you intend to use it "as is" or you intend to do some modifications in the output voltage? Because I intend to power 4 amplifiers of about 150w/ 8ohm from it. Right now i'm building the amp but i don't know it's exact power requirements (quasi's design).
quasi said that it should work at around +/- 50v but I prefer to build the amp first, see how it works and after that build the power supply. Anyway if quasi is right (and i don't see why not) i have to modify the power supply (increase a little the two 36,5k resistors R32 and R28).
Ok, enough talk for today....
I'm looking forward to hear that K6 SMPS is working well...
have a nice week-end
cheers
I've tested the K6 so far at 400W output, and without feedback loop (a PWM control potentiometer temporarily spring-clipped onto the UC3525 to vary duty cycycle). Works well, and the mosfets stayed at around 65 deg C -- with no heatsink. I'm running out of good dummy loads at these powers. Next load will have to be a 1000W space heater.
The switching node waveform is not very square, owing to the poor drive capability of the controller IC. The IC can drive about 400mA peak, per output, but since both outputs are in series here, that's 400mA total, for all 4 MOSFETS. (and they all have to be driven simultaneously, 2 on, 2 off, drawing 4 simultaneous drive currents from the controller)
The high capacitance and gate charge of these devices require ample drive current (4A + per device) to produce fast switching waveforms. I'll eventually re-build this circuit with TC4422 gate drivers for each mosfet.
The IRFP450's have an obscenely high gate charge of 150nC. You can do much better than this if you go outside the IR series.
I've tried replacing them with Fairchild FQA16N50 ( 60nC gate charge), and the latter run less hot. (they switch faster, preserve a sharper waveform, and spend less time in the linear conduction region.)
Another improvement I've made was to increase the Vcc to the controller from +12V to +20V, to get more output drive. At the same time, I've decreased the turns ratio on the gate drive XF from 1.17:1 to 1.55:1. The net result is more voltage to the gate (12.9V instead of 10.25V) AND more current capacity.
I could post some pics and waveforms if others are interested in building this thing.
Adrian
The switching node waveform is not very square, owing to the poor drive capability of the controller IC. The IC can drive about 400mA peak, per output, but since both outputs are in series here, that's 400mA total, for all 4 MOSFETS. (and they all have to be driven simultaneously, 2 on, 2 off, drawing 4 simultaneous drive currents from the controller)
The high capacitance and gate charge of these devices require ample drive current (4A + per device) to produce fast switching waveforms. I'll eventually re-build this circuit with TC4422 gate drivers for each mosfet.
The IRFP450's have an obscenely high gate charge of 150nC. You can do much better than this if you go outside the IR series.
I've tried replacing them with Fairchild FQA16N50 ( 60nC gate charge), and the latter run less hot. (they switch faster, preserve a sharper waveform, and spend less time in the linear conduction region.)
Another improvement I've made was to increase the Vcc to the controller from +12V to +20V, to get more output drive. At the same time, I've decreased the turns ratio on the gate drive XF from 1.17:1 to 1.55:1. The net result is more voltage to the gate (12.9V instead of 10.25V) AND more current capacity.
I could post some pics and waveforms if others are interested in building this thing.
Adrian
hello Adrian,
I agree with you on increasing the gate - source voltage on the power mos-fets, I personally go with a voltage of around 15-17 volt on gate source. But I don't know how you intend to insert the TC4422 drivers in the circuit. They have high curent capability but they are low side drivers - you can not drive the high side mos-fets, and what about the galvanic insulation between the power mos-fets and the rest of the circuit? From my point of view it's easyer to insert a buffer between the SG3525 and gate transformer. A small buffer made from 2 transistors tied emmiter to emmiter and base to base (NPN and PNP) for each leg of the primary winding should be enough.
I agree with you on increasing the gate - source voltage on the power mos-fets, I personally go with a voltage of around 15-17 volt on gate source. But I don't know how you intend to insert the TC4422 drivers in the circuit. They have high curent capability but they are low side drivers - you can not drive the high side mos-fets, and what about the galvanic insulation between the power mos-fets and the rest of the circuit? From my point of view it's easyer to insert a buffer between the SG3525 and gate transformer. A small buffer made from 2 transistors tied emmiter to emmiter and base to base (NPN and PNP) for each leg of the primary winding should be enough.
The MOSFET drivers would go before the GD transformer. And I would probably want to use 4 transformers, one for each gate. Many drive configurations could work, both integrated and discrete; I just happen to have the 4422's from an auction bulk purchase.
The transformer would not constitute an unusual load for the 4422's, since it reflects the heavy capacitive load from the gate to the primary.
The design as it is runs very well, and I'm sure it would perform exactly as it's designers intended, given the right heat sink and fan cooling. I just think we can get this thing working with no fan and a smaller heat sink, if we can speed up the rise/fall times on the switching node. I've measured 1us rise times with the original design, brought down to about 0.5us with higher gate voltage and lower Qg switches.
I'm definitely completing this board as-is. The 4422's will require a PCB redesign, wich will come in the next build.
Adrian
The transformer would not constitute an unusual load for the 4422's, since it reflects the heavy capacitive load from the gate to the primary.
The design as it is runs very well, and I'm sure it would perform exactly as it's designers intended, given the right heat sink and fan cooling. I just think we can get this thing working with no fan and a smaller heat sink, if we can speed up the rise/fall times on the switching node. I've measured 1us rise times with the original design, brought down to about 0.5us with higher gate voltage and lower Qg switches.
I'm definitely completing this board as-is. The 4422's will require a PCB redesign, wich will come in the next build.
Adrian
what is your sound character
I suggest you build american character If you like to hear
Rap, Rock and Metal
But if you like jazz, orchestra and more specific music you must
build europian character
For me anthony e holton is more than enough is very excellent
maybe you can visit him at the website
http://www.aussieamplifiers.com/index3.htm
regards,
jeffry_widjaja@yahoo.com
I suggest you build american character If you like to hear
Rap, Rock and Metal
But if you like jazz, orchestra and more specific music you must
build europian character
For me anthony e holton is more than enough is very excellent
maybe you can visit him at the website
http://www.aussieamplifiers.com/index3.htm
regards,
jeffry_widjaja@yahoo.com
transformer
You can look plitron transformer
http://www.plitron.com/ssa.asp
it is excellent
regards
Jeffry
You can look plitron transformer
http://www.plitron.com/ssa.asp
it is excellent
regards
Jeffry
Hello guys
After almost two years since I started this topic I'm back.
Unfortunately I was very busy in the mean time and I did not had the chance to finish the amplifier i started to build back then. I saw that Quasi made a lot of improvements on his schematic and the thread is unbelievably long.
Anyway on last friday I finally managed to test the amplifier and like all the guys who built it I am very happy with the results. Until now I only tested it with the signal generator and the oscilloscope but the plots look very promising.
But as I stated at the beggining of this thread I need a power supply to feed the beast. My choice is still the K6 SMPS.
Anyone who finished that power supply has any opinions about it?
Today I ordered the cores to a local supplier and until I get them I could use your experience with the board.
cheers
Daniel.
After almost two years since I started this topic I'm back.
Unfortunately I was very busy in the mean time and I did not had the chance to finish the amplifier i started to build back then. I saw that Quasi made a lot of improvements on his schematic and the thread is unbelievably long.
Anyway on last friday I finally managed to test the amplifier and like all the guys who built it I am very happy with the results. Until now I only tested it with the signal generator and the oscilloscope but the plots look very promising.
But as I stated at the beggining of this thread I need a power supply to feed the beast. My choice is still the K6 SMPS.
Anyone who finished that power supply has any opinions about it?
Today I ordered the cores to a local supplier and until I get them I could use your experience with the board.
cheers
Daniel.
- Status
- Not open for further replies.