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About dracu_n_dulap

  • Birthday 04/05/1990

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  1. Thank you very much for your answer. My, lenghty, question was: for wich inductance do i select the size of the core? For the 7µH resulted from the calculation?
  2. Hello everybody! I have a question about coupled output inductor design. Reading this paper from unitrode, i undestood the physics behind it, but not completely... In the example a forward converter is given with 2 outputs, one is 5 volts 20 amp ( 100 watts ) and the other 15 volts 5 amp ( 80 watts ). For the calculation of the inductance the turns ratio of the transformer secondaries is defined ( as the turn ration on the inductor need to be the same ), then the 15 volt is normalized to 5 volt with a 15 amp and then combined with the other one and herein on treated as a sigle output of 5 volts 35 amp ( 180 watts ). Then the inductance needed is calculated as 7µH, then it's beeing told that since the first output is only 20 amp you have to reduce the area of the conductor and then wind the other output wich will have three times more turns because of the turns ratio. Now the question is for what inductance do i design the windings? I mean do I have to split the inductance between the outputs in such a way that it gives me a 3:1 turns ratio and select the core for a 7µH inductance? Or I make a 7µH winding for the 5 volt output then wind the second 15 volt winding with 3 times more turns and the calculate the resulting inductance then add it to the 7µH from the first output and select the core for the total inductance? Sorry if i am not making any sense but i am asking your help after i have read all the unitrode documents, 3 other separate documents and a thesis about this topic and the info in my head looks like it was in a blender. Thank you in advance!
  3. I hate this type of kits too. They try to maximize they're profit by making you buy another preprogrammed PIC if something happens to the one in the kit. They also have Do It Yourself in the name of the site, it should be Buy It Yourself. I will try to write one my self, see what comes out ;D And if my topic somehow infringes some copyrights , i will ask a moderator to delete it.
  4. yes, you're right. you have to buy the kit, but it is a bit expensive. :( i thought that someone has read the pic and has it ;D
  5. Does anybody has the hex file for this project http://electronics-diy.com/lc_meter.php ?
  6. I have modified the schematic and the part list. It now has R22 at 1/4W, then i gave names to the emitter resistors and put their values in the parts list, the same with the 10v zener and D7. Hope no one minds. :P
  7. Hi! I've built this psu and it works great :D but I was wondering why is R22 (in the latest schematic) a 1W resistor? ??? From my standpoint is just a current limiting resistor for the led, isn't it? and are 2W resistors enough in each power transistors emitter ? i've put 5w to be sure.
  8. 7 A..............i understand a bit expensive to order but ok i made a mistake writing the 2x30 i was thinking about something else and it doesn't have anything to do with electronics ;D was a way for me to say that i have 2 psu tanks! good luck! :D
  9. so.... i'm back again to be annoying ;D to turn my psu into the 5A variant the transformer has to be 2x30V at how much amperes.
  10. ;D yes allready found it and the ic too i will place an order as soon as posible. thank you.
  11. Not another planet, just another continent, europe. From romania. To be honest i still have two places to ask for the opamps, but i asked for epuivalents to have a better chance at finding one of them and finnishing the psu, or even better ones, i mean some that have a higher max voltage for a better safety margin.
  12. hello. ;D could you please tell me if there are any other equivalents to opamps used in the final version of the schematic? because i could not find tle2141 or mc34071 thanks
  13. hi! i want to build an ammeter with icl7107 for my variable power supply (the one on this site) but i ran into a problem with this schematic because one of the inputs is tied to the ground and i cannot use it at rhe same time with this voltmeter. but the schematic on this site has floating inputs and i would like to use it. so if you couuld please tell me how turn it into a ammeter. what i know so far is that i have to add a low value resistor on wich the voltmeter will measure the voltage. that value will be in amperes. so how can i calculate the power resistor on wich the voltage is measured. i know so far that is Ohm's law, is there a specific value for the ic that you have to konw? ??? thanks.
  14. just the question i wanted to ask. is the data recoverable? :(
  15. Hello Could you please tell me what's the value of the trimmers? because in the pdf schematic of the final version they have no value. Those are the only parts that i have left to buy, and i can't wait to get this psu working.
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