pier

Hi AG My multimeter measures 17.3 volts across the 100/25 capacitor. What will be the o/p of the LM317 ? Hows the circuit now ?

Hi AG I could find an lm117 as a current regulator circuit in the datasheet (application notes) 317 is used as a voltage regulator and a reference with voltage regulator . Is this the same way i should do to the lm317 (picture) ?

Hi AG How about this circuit, and the current regulator you suggested me . If correct what could be the value of r3 ?

Hi AG, Sorry for the 7805, it was supposed to be 7808 . On the projects Q/A forum, the lm317 thread you have put up a circuit using 78xx series for current regulation . Shall i follow that ? One doubt : Assume when two leds(3.5v each) are connected in series the current(each led = 350mA) through both is same. So, is the total current drawn from 78xx series(to220) is the same as the flowing current(i.e, 350mA) ?... ???

Hello AG I bought 2 new 1watt white led (lumileds), Its specifications are 3.5volts DC 350 mA Since it is a costly one , As you suggested before i would like to use a isolation transformer(9 volts, 500mA), Bridge rectifier(w10m) a good filter(1000uF/16v) . For the 3.5 volts I dont know what to do . My idea was to use a 7805 with good heatsink and a voltage divider for 3.5volts DC and put the 2nos of 1watt LED's in series . Is this correct ? Or I have found a link http://www.national.com/webench/ledrefdesigns.do Should i use something from this Ag . Please Suggest me . Thanks Pier .

Hi AG I removed the led light from the roof top to put a better heat sink and when i touched the track side i got a good shock, The capacitors were still charged . Should i put and resistor across the capacitor bank so that they get discharged as soon as it is put off ? If so which would u suggest the value to be and its wattage ? thanks & regards.

Hi AG Thanks for the circuit. Actually I am not building the circuit for 6 led's but i wanted to know the calculations for deciding the number of led's used for certain voltage available because i read somewhere in the web that u can use leds in series provided the voltage across the led string should not exceed 0.9 X Vcc volts.So As i asked in the topic before as per my assumation i took 3.5volts per led and voltage available is only 21 volts , 6 led's take the entire voltage(21 volts), so i was confused if it was right to do so ????The other circuit u gave me for 49 leds is still working excellent on my roof top :D :D . Regards Pier.

Hi AG Now suppose i have only 21 volts dc at the o/p of the power supply and i have to connect led's in series . Assuming the forward voltage is 3.5volts, can i connect 6 in series so that the total forward voltage reaches 21 volts dc ? I dont know the exactly how to calculate the number of led's to connect in the circuit . Can u please help me in this ? Regards Pier.

Hi AG I made a board of 72 X 24 mm in size and the same size for the heatsink with a thickness of 3mm . Would this be a sufficient heatsink for a continious operation . I want to isolate the transistor from the heat sink and screw it up (Heat sink)on the roof of my room . Thanks Pier .

Hi AG The circuit was on test for 3 days continiously and working fine . People are asking me how much power it consumes from the mains . Bulbs consume 60Watts as written on it when we purchase it here . Do we have to connect an Ampere meter in series with the live mains i.e.230/250 volts AC to measure its current and calculate its power ? Thanks Pier.

Hi AG Its right as u said . The voltage across the 22ohms resistor is 0.6volts when the mains voltage reaches 345Vdc . The 13005 is getting very hot and i 've put a bigger heatsink now . I will put it under testing and let u know the result after 1 or 2 days . Thanks a lot for ur co-opeation in helping my project AG . :) Thanks Pier

Hi AG I connected 22 ohms . Now the voltage across is 0.58 . How about reducing the resistance little more ? Thanks Pier.

Hi AG I am such a fool, I forgot to connect the 3904 in reverse when i corrected the 13003 properly . Now its fine . The voltage across the 27ohms is 0.56 volts. I dont understand AG how are u able to find faults without seeing the circuit I connected . Thanks a lot AG . as i said is 0.56volts across 27e ok ? Thanks Pier

Hi AG There is no voltage across 27 ohms resistor when i measured it ? what could be the reason ? Thanks Pier

Hi AG Ur great!!!!Thanks for pointing out my mistake . The collector and emitter was in reverse . Now it is very bright and i have a little doubt will it blow off !!! Where do u measure its current AG . I am in front of it now . Thanks Pier

Hi AG I apologise for electrocuting myself :-X . I measured the voltages at different parts of the circuit : across 27 ohms resistor : 0 volts (no voltage) at the base of 13003 with respect to gnd : 14.25 volts across the 10k resistor : 0.59 volts at the collector of 13005 with respect to gnd : 152.22 volts All this voltages was measured when the input voltage was 300 volts DC. No components are heating up . Thanks pier

Hi AG The circuit works fine now, but no brightness . Before with high wattage resistor it was really bright . But now it is less . I forgot to tell you AG that I am using 49 white leds . What could be the reason ? Thanks Pier.

Hi Ag I am still searching , I've asked a shop owner for the same and he said he will let me know in 2 days . By the way AG hows 13003 for the small one ?

Hi AG Thanks a million :D.The circuit works!!!!!!!. The 13005 is warm with a heatsink . I tried till only 280volts dc . I have to look for a high voltage transistor of to92 package (400volts as you said) for testing till the higher end of voltage . Mean while if you find some part numbers please let me know AG . I will look for it, if it is available here . Thanks :) Pier.

Thankyou so much AG, I am using MPSA42 as the small high voltage transistor . No problem naa ? Thanks Pier .

Hi AG Thanks a lot for the circuit . I will build the circuit today itself and test it, but one doubt (must be a dumb one, dont feel bad : i am weak in electronics) as u said before should i connect a high watt resistor as per previous calculations for the led's in series ?!!! Thanks Pier

Hello AG I tried , there are only 80 to 100 volts available (darlington) .I found a bu808 on the net but i dont get it here. Can we do it with a 13005 ? . Thanks Pier

Hi AG, How do i do that ? do you have any circuit for that ? and till what voltage can we regulate ? . Wont that be tough AG to regulate such high voltage!!!! Thanks Pier .

Hi AG I am sorry for asking that question . I looked into the datasheet only after posting my question, But I would still like to know the element Which is used as a reference . I am interested to build it and test it AG if you give me the values . I dont mind if it takes some time even . Thanks Pier .

Hi AG The circuit looks complicated but it is of interest to me . I dint understand what is that reference (200mV) you mentioned .