looking for high power regulator  - Page 1
Forum section: electronics / projects

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 09, 2012, 10:02:28 am
content: hello well , I am looking for 40W regulator , but it's a bit tricky ,I need it to go all the way down to 0V ( actually , I am looking for something like the LT3080 )I am building a 75W power supply (in fact 4 of them) now . each one will be isolated (IE floating ) and I am designing a versatile power supply total power rated of 300W , (yes . allot of power is gonna be dissipated here )as Dave said " you can never have too many power supplies "well, thank you in advance for any replay !

author: T4P
author_rank: Super Contributor
timestamp: March 09, 2012, 10:20:37 am
content: Use a external NPN pass transistor , or roll your own regulator and use a better npn pass transistor .But 40W sounds like a lot ! ( i'll give you a example of what a heatsink looks like for 50W .. I think 1C/W or 0.5C/W ? )

author: Ajahn Lambda
author_rank: Regular Contributor
timestamp: March 09, 2012, 10:23:54 am
content: Check out the attachment. It's a part of the LT3080 data sheet that might help you realize higher output current, while using the same chip, plus a pass transistor.

author: Psi
author_rank: Super Contributor
timestamp: March 09, 2012, 10:28:51 am
content: If you want something exotic you could use a 5-10A opamp like a OPA549You'd probably need a +/- supply to get down to zero output though.But you'd get a power supply that can both source and sink, which is cool

author: grumpydoc
author_rank: Super Contributor
timestamp: March 09, 2012, 10:29:50 am
content: If you're aiming to build an 0-30V 10A power supply have a look how the commercial ones are built - some googling will get you schematics.The one I've just fixed (0-30V, 20A) has a pretty straightforward design - a couple of 741 op-amps driving a set of parallel 2N3055's (via a Darlington plus another intermediate 2N3055 to get enough base current).Their approach to keeping dissipation low - i.e trying not to have to get rid of at least 250W of heat if you set the output at 5V, then draw 20A from it - is to have multiple windings on the transformer and a set of meaty relays which switch them in and out so that the unregulated supply approximately tracks the output.Obvious, once I'd seen the design.

author: T4P
author_rank: Super Contributor
timestamp: March 09, 2012, 10:49:17 am
content: http://www.microsyl.com/index.php/2010/03/31/bench-power-supply-0-25v-0-5amp/Relays and multi-taps is a good idea , switching supplies are common for 10amps onwards .There's no point of a high power opamp , a external 3080 is cheaper considering you can use a offtheshelf opamp and decide which pass transistor you want .But a switching supply or relays and muli taps is a better one .

author: Psi
author_rank: Super Contributor
timestamp: March 09, 2012, 11:14:47 am
content: wow, you're not kidding, i just checked the price of the OPA549.I was given an entire tube of them and i just figured they were worth a few dollars, but they're NZ$31 each!!It makes me want to build something with them even more now

author: T4P
author_rank: Super Contributor
timestamp: March 09, 2012, 11:37:58 am
content: Quote from: Psi on March 09, 2012, 11:14:47 amIf you didn't know alreadyHigh power opamps are definitely a pain in the arse to have , it's so expensive !

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 09, 2012, 11:58:37 am
content: well thank you for the fast replay'smy idea was 4 power supplies , each goe's up to 75W15V@5A each ,now I have "re wound" 2 microwave oven Transformer's , and they both capable of about 1000W (500W each)so that was the primary coil , now I'll do 4 winding's , 15V@5A each (well , actually I think that I need about 20V-no load in order to get 15V stable output, but I guess you'll tell me so ) .the power supply will be big , I know , and heavy either , but I'll get use to it ,as instrument I already have 2 fluke's meter's ( the legendary -87V and the 287 )I am just beginning with building up my lab , so power supply is extremely importantand I know it isn't the topic , but I am buying a HP-3478A , do you think it's a good idea ?I thought to use him as sort of calibrator , IE do a side by side comparison's in order to tell whether my meter's are out of spec's or not ,well , back to the topic , I need the total cheap to be something like 10~20 (to-220 pack's )because of the size of the heat sink (17.5 by 13 centimeter's ) and yes , he's passive one . therefor I attached nice 120 fan , and last time I have checked (based on cheap thermometer ) that was about 47C with 250W load and ambient of 31C . IE . 0.064C/w or so .then ^T will be 19.2C (above ambient ) at 300W (but that's will be the heat sink temp , not the to-220's packages ,thank you in advance !

author: Ajahn Lambda
author_rank: Regular Contributor
timestamp: March 09, 2012, 01:56:41 pm
content: Quote from: eevblogfan on March 09, 2012, 11:58:37 amImportant, yes. But do you truly need such output current? It's not terribly high, relatively speaking, but 5 A for just starting out seems a bit much to me. The higher current drives up the requirements of everything else, e.g. transformers, heat sinks, pass elements, etc.Just my opinion and experience, but it'd be much more useful to have a stable, clean, hassle-free and easily-adjustable power supply, rather than one capable of high current (UNLESS there is aspecific needfor it).If you could possibly be happy with a 3A current output,look at the LT3083. It is basically the same as the LT3080, but with a 3 A current limit, which is more than enough to cause some damage.Do you have a design for mains filtering yet?QuoteAgain, paralleling the LT3080/3083 is easiest, but an external pass element affords more flexibility in current handling. It's up to you to determine the best 'bang for the buck'.Personally, I'd go with one or two of those LT30xx chips in parallel. Cheap, simple, and it works.** EDITED part numbers -- accidentally used "LM3083" instead of the proper "LT3083". Bad habits die hard.

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 09, 2012, 03:32:20 pm
content: hey , thank you for replay meI know what 5A are , the whole Idea was to put all my Needs into one bulky box , later on I'll be able to parallel either series combination for all of these 4 internal unit's , I didn't really understand , the LM3080 cant work with 75W (either 37.5W each ) . I need something more serious , yes , external transistor is capable of perhaps infinite power dissipation , the question is either it can be as stable as the lm3080 itself ,if so , way shouldn't I get chopper amp and set it up like Dave's power supply circuit ?well perhaps it will not be stable at all (it will , but just for limited range or so )what I end up with, is either 4 unit's (15V@5A each ) or 8 unit's (15V@2.5A each )well in terms of power dissipation it's the same , but the 8 unit's idea is more versatile indeed ,well , assuming I'll go with the 8 unit's idea , the lm3080 cannot work with perhaps more then 1.7W or so , it not getting close to 37.5W , therefor , I have asked for high power regulator , perhaps as high as 40W or so ,and I didn't mention , though I am beginner , I have started electronics since 2009 ,but all I had was batteries , therefore I decided that power supply will be much better [I find out that batteries doesn't have CC mode, ask my dozen silicon IC's who tosted like nothing with the 400A (for 10 sec ) and about 1200A(250 uS , based on the pick voltage in my fluke 287 and not that accurate 1mOHM shunt) ]well ,I hope I didn't missed any point , thank you allot !

author: T4P
author_rank: Super Contributor
timestamp: March 10, 2012, 04:22:07 am
content: You really should be designing a switching supply , a little complicated and it might seem expensive at least you save big bucks on heatsinks and large caps .Mind you per ampere that you want to draw means 1000uF which means what ? 200,000uf combined capacitance ? WOW .

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 10, 2012, 06:06:36 am
content: hey well , unfortunately I don't have any experience with SMPS ,the big Buck's spending is perhaps behind me (I have already got the heat sink and the transformer ) about the capacitance , way should I do such a huge bank of cap's ?I know we need the capacitance , but way not use the regulator either ?maybe I'll build a filtering circuit (low pass filter ) but hey , I am not that on focus (I just woke up , ) so please , you do the decision , I am really "drunk" now ........BTW , I don't have any scope ,(I decided to wait with it , I don't know what competition will be after rigol's new scope's or so)thank you for you're replay's !

author: T4P
author_rank: Super Contributor
timestamp: March 10, 2012, 07:23:02 am
content: Quote from: eevblogfan on March 10, 2012, 06:06:36 amThat's with a regulator , not with a regulator .You need to build a external LM3080 ( sub with a better , bigger transistor ) If you want to put out 75W but remember you need 4 of themAnd 5000uF each ( sorry i meant 20,000uF )

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 10, 2012, 07:53:47 am
content: well , good newsI have 10 P's of 2200uF@63(WV) >? umm , I assume it's V , but written WV , what is that suppose to mean ?and , yes , 4400uF will be for each power supply , I guess it will do (If not , I'll buy 4X600uF ) either take out of old power supplies .I haven't check each individual one (since the'r all in the nylon)but I'll check them later on (I haven't LCR meter, but I do have the fluke 287 abillity with Capacitance , If memory serves me right It can measure up to 100mF , so no problem)now the main subject , I have 4 IRFP064N's , I thought to use them ( each one can Handel easily 40W with the to-220 , but I have 4 of them with TO-247AC , they will be goon enough perhaps 2 per power supply will be "over kill ")but can we do this with mosfet's ?and what will be the shunt's resistance ?what will be the shunt's Amp? either diff one or low offset chopper one (maybe in diff configuration ? )BTW , assuming we done with the power supply , is someone can design it for me and produce the circuit (I'll pay for the bill's and for the job )I am saying that since I don't have any experience with PCboard's and ficoese not with manufacture them .... all I got is this copper ring's board . lame ! though fast

author: T4P
author_rank: Super Contributor
timestamp: March 10, 2012, 08:30:11 am
content: Do not use protoboard with this high power stuff , you'd either need a HUGE mass of solder or your pad needs to be very thick .In any case , i'm not sure if mosfets can be used or not . And i'm not sure if you want current control or not .But in any case , it's TO-3P package and it's 0.008ohms ESR make it very desirable .At 5 amps the VD is only 40mV and 40mV*5 = 0.2W extra heat .75W + 0.2W = 75.2W ...

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 10, 2012, 08:52:39 am
content: heydid you ment for the IRFP064N ? if so , on menual it says TO-247ACor the classic 2n3055 (To-3p) but , transistors doesn't have ESR (IE , Rds-on)and yea , 0.2W extra either 0.8W total , umm , I think the bridge rectifier will not suffer that and explodes on my face ><"now , as I mentioned be-for , the transformer sec isn't wrapped yet , therefor I can do anything all the way up to 1000W perhaps continues , so even If I'll need an extra 200W for some bizar reason , I'll be able to ,BTW , I haven't thought about it , maybe I'll do fixed 5V and fixed +/- 12 either 15V output (perhaps 1A at the +/- one and 5A on the 5V one , IE. extra 55W or so )BTW , I did topic on the panel meters I wanted to buy , well I recently got 2 of them , they was about 0.2% out , but I calibrated them and now they're about 5 Digt compare to my 287, perhaps they'll need cal every month or so . but it's not that critical for 20,000 meter ,thank you i advance for the great support you're giving me here!

author: T4P
author_rank: Super Contributor
timestamp: March 10, 2012, 01:54:49 pm
content: 247 is the same as 3P , 3P is the larger brother of the 220 .0.2W is nothing extra really so it's all good , so it's all fine , i love LED panel meters5V 3amps to be like the offshelf products and 5 adjustable +15/0/-15 5A and a +12/0/-12 1Amps .Many devices , but the two other ones can be accomplished using 7812 and 7912 and a 3083 configured for 5V ( but it should also come off another 3083 configured for 9V )

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 10, 2012, 02:35:04 pm
content: heythanks for replayI am trying to focus on the major thing in this project , the power supply ,now just for the record , assume I need to build only one -75W 15V@5A PS ,what will be the regulator ?what chip can Handel that power ?can I do this with my IRFP064N's ?if yes , what would be the circuitry >? (because of the non linearity, and the high voltage gate recommendations ) -I prefer from -1~2V (Rds-off) and 12~14.80V (Rds-on )will I need some inductors? (I am asking because I don't have any LCR meter , but I have allot of ATX PS and computer motherboards )thank you in advance !

author: T4P
author_rank: Super Contributor
timestamp: March 10, 2012, 03:46:59 pm
content: You don't need an inductor , but an LT3080 output that turns on the IRFP064N .LT3080 because that's what you know , and i'm working on using a LM723 turning on a MOSFET or a BJT , but anyway , i would use/design a switching supply .(I do electronics engineering on power engineering at home , while i have basically nothing to do at school (I'm 18 and in a pre-polytechnic) but i have one massive robot to build)

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 11, 2012, 09:55:00 am
content: hey , sorry for delay (I am Ill )well , I really wish you good luck with you're plans , BTW . I am 2 years older then youI cant find the lm8030 within the LTspice . can someone help here ?thank you in advance !

author: Bored@Work
author_rank: Super Contributor
timestamp: March 11, 2012, 10:16:42 am
content: Quote from: eevblogfan on March 11, 2012, 09:55:00 amAttention to detail, please. It is not the lm8030, it is not theLT8030, it is the LT3080.

author: Ajahn Lambda
author_rank: Regular Contributor
timestamp: March 12, 2012, 12:06:09 am
content: Quote from: BoredAtWork on March 11, 2012, 10:16:42 amI'll take some blame for that. I used the LM prefix instead of the proper LT in my own posting, but I've corrected it, and left a note at the bottom indicating the change. Sorry for any confusion I may have caused.

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 12, 2012, 03:55:35 pm
content: well , perhaps that is the last day I am ill (I have no heat anymore ! )maybe today I'll start with the schema , yesterday I felt horrible while staring the LCD ,thank you in advance !

author: williefleete
author_rank: Regular Contributor
timestamp: March 16, 2012, 03:56:31 am
content: make one. i've gutted out a sixties era adjustable supply and gave it some modern stuff. LM324, LT431 as a 2.5 volt ref, voltage follow that and use that to supply the adjust pot. and use one (or two if you want the gain set on another opamp and have the driver as a volt follower) to drive a burly darlington transistor, bit of noise on the 0 volt setting and not too sure of no load zero volt offset but i've made something similar and it works ok, with around 50 odd mV noise and reasonable regulationpower transistors should be easy to come by or rip one out of a TV and use a smaller power transistor from the opamp out to drive the bigger ones base

author: Rerouter
author_rank: Super Contributor
timestamp: March 16, 2012, 06:52:55 am
content: like has been said before, for that level of wattage, it would probably be wise to use a switching pre-regulator, then you could just as well get away with an op amp and a big pass transistor like a 2n3055t to stabalise it and remove most of the noise of the switcher, while keeping your wattage down to near nothing,i say op amp instead of a LT3080 or similar being how you can easily manage a small negative tap for each rail, so can manage down to 0V without issue, just would need a op amp able to supply a few hundred mA, or with a darlington arrangement, just a stock standard quad op amp package, so you could even play with constant current, and making the switcher track the linear output,though if you want the negative rail trick can be used just as effectivly with any other LDO regulator to pull down its set pin to offset its dropout voltage, and make a minimum load much simpler,

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 16, 2012, 09:31:16 am
content: heythank you for helping me .are you talking about 300w ? or 75W ? either of them . I need the power supply to be linear not half switching (I saw the "tracing pre regulator" ) .I also need it to be made out of mosfet's ( I am working on the circuit but from some reason I cant make the simple "linear Dave's power supply" on the LTspice .I also notice that changing the sort of opamp give's me whole another result . if so . what opamp should I chose for that purpose ( the simulation only . ) ?I think the 75W should be dissipated by 2 IRFP064N's (TO-220) , perhaps each one can Handel about 40W simultaneously . so two will be able to Handel 75W no problem ,since I am newbie , I'll ask , what is the difference between "LM" and "LT"( linear tec ) and lm ?and I'll ask . why do I need to use transistor (current controlled and not so much efficient ) instead of mosfet (voltage controlled . very efficient, in terms of Vd at full load . )thank you in advance !

author: T4P
author_rank: Super Contributor
timestamp: March 16, 2012, 09:57:00 am
content: Quote from: eevblogfan on March 16, 2012, 09:31:16 amALL Transistors are voltage controlled .http://amasci.com/amateur/transis.htmlLM is by national semicon and LT is by Linear Tech .75W is a shitload of heat to get rid off, you can have a switcher and then a linear after that, less heat to get rid off , less money spent on a massive heatsink .

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 16, 2012, 10:36:19 am
content: heythank you ,I know that they're not really "current controlled" but with mosfet's you can put only 200uA or so in order to fully open the gate and with transistors you really can't , ( much higher current ) .the reason I am not buying a power supply is because all of the costy stuff are here on my desk (IE . power transfromer , and big heat sink, and 2X4.1/5 20,000 count panel meters ,now I "only" need the circuit design and circuit manufacture and I finish ! (I know , it's much more harder)now , on the begining of the power supply series , dave sais that he can also do that with mosfet's but he will not explain , would someone explain me how to ?I know that the "usual" opamp+mosfet/transistor CC either CV circuit is so noisy , please tell me you have some chip either some sort of circuit who can fit here. even a 30W one ( I'll build 3 of them in order to handel the ammount of power needed ,)thank you in advance !

author: T4P
author_rank: Super Contributor
timestamp: March 16, 2012, 11:39:00 am
content: Quote from: eevblogfan on March 16, 2012, 10:36:19 amWith that sort of stuff , i give the thumbs up to go true linear ! How big is it actually ? 20,000 counts panel meters ! Where did you get it ? You must have paid a bomb if it wasn't free !

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 16, 2012, 11:47:34 am
content: heysarcasm ? either serious ?BTW , 20,000 count meter isn't as costy as big 300W either 1KW power transformer , or big nice heat sink ,thank you in advance !

author: Rerouter
author_rank: Super Contributor
timestamp: March 16, 2012, 11:48:35 am
content: The half linear design is simply so you can get away with small thermal considerations, if the linear only needs to handle 1-5w in place of the full 75w per rail.as for the MOSFET to regulate with them means operating them in there linear region, just below the rated voltage for rson, however mosfets are not ideal for a supply as they have gate capacitance delaying there response to transients unless driven quite hardAs for op amp regulators being noisy its is partly correct was just throwing up the option any regulator with a set pin can function adequately pulling it below zero with some pissy little milliamp rated winding is all thats required, and allows an output voltage down to zero, with how much voltage just being the net offset voltage of the regulator and the pass element

author: Rerouter
author_rank: Super Contributor
timestamp: March 16, 2012, 11:56:22 am
content: Even though you have the giant heatsink I wouldpersonally prefer to not have a piece of metal close to or exceeding 100 degrees in my lab, but if you wish to go linear then by all means sounds like you have the pieces to do it. As a secondary throught if you went with full linear how would you isolate you few thousand uF capacitors from boilingI don't mean to sound pushy just been jumping through these hoops myself recently

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 16, 2012, 12:13:50 pm
content: heyyes . I do have bearskin( I indeed get burn regularly and it "stops" been hurt)BTW , 100C with 0.064C/w heat sink will need about 1250W (with ambient of 20C )so it's kind of allot powerassuming I do want this 75W power supply be linear , and I do want to get burn , will you help me figure out the circuit needed ?thank you in advance !

author: T4P
author_rank: Super Contributor
timestamp: March 16, 2012, 12:50:35 pm
content: I can figure out how my largest heatsink is extremely inferior to your heatsinkI believe all you need is to use BJT's instead , controlled by a LT3080 .Let the others help you out , i'm not too good at this area yet .

author: A Hellene
author_rank: Frequent Contributor
timestamp: March 16, 2012, 01:06:59 pm
content: eevblogfan,hereis a couple of suggestions on how to use the LT3080 to drive a 300++ W power stage. Q2 is a (low saturation voltage) current amplifier that drives two (or more) forced air cooled 150W (or more) power transistors. Of course, to fully utilise the LT3080 capabilities you might need faster power transistors than the 2N3772/2N3055 shown at the drafts.Quote-George

author: Rerouter
author_rank: Super Contributor
timestamp: March 16, 2012, 01:19:10 pm
content: sorry about that, combination of overlooking the junction and iphone "auto-correct" still as for a mosfet, i am really struggling to find a design that responds to wide variations in loads,however this seems to be one you can play with simulating,http://cdn.head-fi.org/9/91/1000x500px-LL-91977a40_mosfet-voltage-regulator-circuit-diagram.PNGif uses a voltage doubler arrangement to get enough voltage to properly drive the mosfet, though you could well just use another puny winding to get a higher one,as for the actual transformer, i assume you know the number of windings in the primary and how to calculate how many you will need on the secondary, if not just post the number on the primary, and the gauge of wire your using, (will be a voltage drop in the windings that needs to be compensated)to go furthur into that circuit, it would seem that the higher voltage is being fed in and being pulled down for control. with some feedback off the output, then fed into an adjustable voltage reference to keep it accurate and stable,

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 16, 2012, 02:01:28 pm
content: heyI cant really tell you what is the winding count , because I didn't really count it . I just winded ><"well I ran a little experiment , and the result are :no loadV input : 223.4VRMS (the 87V says)V output: 4.355VRMS (the 287 says)now with loadV input : didn't cheked ,V output : 3.62VRMS (with 50W 12V halogen lamp )A lamp : 1.93A (the 87V says)number of windings on the secondary :5 ( 9m'm wide cable)I hope it will help .thank you in advance !

author: T4P
author_rank: Super Contributor
timestamp: March 16, 2012, 02:15:25 pm
content: You most certainly have to rewind ... 15VAC is the target .

author: Rerouter
author_rank: Super Contributor
timestamp: March 16, 2012, 11:43:39 pm
content: (4.355-3.62)x1.93 equals about 1.42ohm of impedence on the winding, almost 1cm thick seems a tad crazy to think of unwinding,now just at a guess, i am going to guess your going to remove that and wind on your own with thinner gauge wire, if so, count the number of turns, at the moment the ratio is somewhat close to 52:1 primary to secondary, however you will need to bring that close to 13.5:1 to get it able to handle 16V under a 5A load, 16V as you will have some drop out voltage,as for the guage of wire, i would say something close to 2.5mm CSA, or AWG10, you can get away with less, this is just trying to keep the temperature increase in the windings down, any neagtive or positive biasing windings can be as low as AWG30 as its milliamps,

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 17, 2012, 10:45:05 am
content: heythank youthe "big transformer" is 2 "E" core out of 2 microwave transformers , and they re held together with a"hand held vise " , so in order to "rewind" I just have to release the vise and then pole the windings out of itand the winding will be as easy as needed ,BTW :I measured the size of the transformer .the S of the winding area is (1.4X5X6.5)=45.5CM squared (for each side )the H is 5CM and the W is 1.4CM and the D is 6.5CM (each side )is that help ?BTW , I don't have 10AWG winding wire , and I remember someone has told me that as the thickness of the winding wire goes low , so as the loss of the copper goes low , is that true ?if so , I think I have like 150 meter's long 18AWG or so , is that better one ? I mean, 18AWG can pass about 8A no problem (http://www.geocities.com/CapeCanaveral/Lab/9643/awg.htm)so that's the wire I was going to wind with , am I wrong ? IE , 10AWG can pass 32A , isn't is crazy ?oh and I don't know If I am right , the Resistance of 10m 18AWG is 0.214ohm , so the max short circuit current is 16/0.214=74.76A ?if so , the max current of 10m 10AWG will be : 0.0334ohm , so 16/0.0334=479A .almost any diode will die with that sort of current , huh ? . well I hope I am wrong with that calculation ( I don't understand transformer's calculations , and I know you've got the inductance and impedance that should be count either ,)oh and BTW , is the usual schottky rectifier diodes (in ATX power supply ) will be good for that purpose ( IE , full wave rectifier built by them )if so , I have so many , I can build a welder rectifier out of themthank you in advance !

author: Rerouter
author_rank: Super Contributor
timestamp: March 17, 2012, 11:25:53 am
content: the other stuff i will have to wait till tommorow to have a good think about, as for AWG10 it was soley a reccomendation, being how the nature of bunched up windings mean they get a little hot from any losses,i wasnt working of theoretical maximum current, just peak capacitive loading, and keeping your temp and by such losses a little lower, AWG18 still feasable.as for diodes, aim for high current, the large value cap will on start up try sucking down all it can get, that was why i aimed for such high currents, up to 50A for ~ 1/15th of a second on switch on,still i will say knowing exactly how many turns on that output instead would make it much easier to spit out a value for you to wind to, but by tommorow i might have remebered something to work off the measurements,

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 18, 2012, 09:28:52 pm
content: heybased on the ratio , I calculated the number of turns on the primary coil . it was 260turns,now , the coil is "super heavy " heat shield, IE , very thick isolation . besides the usual Emile isolation . it has some yellow ( I don't know what is that stuff , but it keep leaving good with nearly 300C )and he is about 1mm thick (18AWG)so , I'll ask , the heavy shielding causes loss in terms of room inside the core , I'll ask if I can wind another primary , this time out of my 18AWG coil . how many windings should I do ? (I haven't measured the bias current taken while without any load , but I assume it's allot ,less winding then 260 , will rise the given voltage achieved by one winding on the secondary coil ,while more then that will lower it , assuming the lowest voltage will be 203VRMS , and the highest will be 234V. at 50Hz ,thank you in advance !

author: T4P
author_rank: Super Contributor
timestamp: March 19, 2012, 03:43:40 am
content: You mean "quiescent current" don't you ?

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 19, 2012, 11:36:55 am
content: heyI was tier when wrote this , please forgive me for any silly mistake , I ment the current that the transformer takes from the wall while ther's no load ,thank you in advance !

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 19, 2012, 12:41:15 pm
content: heyI ran a simulation :and the results :can someone tell me where I am mistaking ?thank you and sorry for double post .

author: A Hellene
author_rank: Frequent Contributor
timestamp: March 19, 2012, 03:06:51 pm
content: Quote from: eevblogfan on March 19, 2012, 12:41:15 pmHello eevblogfan,If you are addressing me, the author of theorignal designyou have modified and posted above, I expect that you have already taken into account my numerous remarks about:1. The very long overload/saturation recovery times the vast majority of the Zero-Drift op-amps suffer from. For example, the LTC2050 input overload recovery time is 2ms, which makes the device too slow to participate in such a fast (>100kHz * 2..10) feedback loop.2. The response time and the stability of the LT6105 current sense amplifier, especially at that high amplification gains (20 V/V), where noise becomes an issue.3. The original design beinga draft, which means that there are several oversights or omissions. For example, the LT3080's operating current of a few milliampers is directly fed into the load, bypassing the current monitor circuitry.Finally, that I posted the design asa draft, in order to suggest a couple of possible solutions for a low voltage op-amp that drives a high voltage load, and not as a design complete and ready to be implemented.This is hardly a finished design; it is just a proof-of-concept model.-George

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 19, 2012, 04:26:37 pm
content: thank you GeorgI assumed he isn't finished yet , I assumed the LTspice suffer from few disadvantages either . so I post the circuit as I thought it will fit my own needs . I haven't read all of the topic , yea I missed up here ....anyway, I presume I'll make a new drift ,here drift :and here result :BTW . I wind 20 windings and the ACvrms was 17.4V or so , the DCv was 22V all of this without a load ,now with 5.4A load , I had about 17VDC !but the strange thing is , way the transformer take 3.9~4Aac no load . and 4.3~4.45Aac with 93W load ! ? ! ?it's like 892W no load and 992W with 92W load ! ? ! ?edit:with overkill config , I literally "kill" the transformer ,I'll go and rewind the primary againe ..what is the number of winding I need to do in order to achieve about >/= to 1A of current (no load )the coil will be made out of the same 18AWG usual emile wier ,the data I have is :with about 260 windings I get 3.9~4A (no load )and with another coil I added ( another 220 windings but 10 ohm in series , IE total of 13 ohm , it draw 0.3A and it was very quiet , no noisy buzzing anymore)in order to achieve 4X15V taps and end up with quiet transformer , since I dont know transformer's theory , I am asking you to tell me way is the number of winding (I dont know what difficulties are hidden after this question , so please consider that )Wat's wrong now ? ( I really don't know )thank you in advance !

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 22, 2012, 08:06:53 pm
content: heyI just try some formula I thought about ,mains V /R (coil resistanse) = /(mains freq) times crest factorso220/1.45= 151.72151.72/50=3.343.34*1.3=3.9448 (about the same current the transformer draw )is that formula real ? is this ok ?thank you in advance !

author: eevblogfan
author_rank: Frequent Contributor
timestamp: March 24, 2012, 07:37:19 am
content: heyI found and "mark" this power supply schema :It's Agilent E361XA 30W power supply ,I would like to ask you people , how can I modefie this power supply for my needs ( E.g higher power pass transistors+upgrading the driver circuit , or so ... )I am sorry for my 3'rd post in raw ,thank you in advance !