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pier
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Hi AG
Assuming the current drawn by each LED is 350mA . I have connected a 500mA transformer for the whole circuit . Now to make 5 LED's work together, Will it be good to put them in series with a transformer of more o/p voltage? Because the i/p to the regulator is maximum 40 volts i guess !! I am not sure. Will it be safe ? -
Thanks Ante I've got the Idea now .
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Hello AG
Philips has a certified a manufacturer for this http://www.polymer-optics.co.uk/Supa-Hex%20Range%20(Luxeon).pdf . -
Hi Ante
Do You mean the outer diameter of the knob should be big for lesser torque we apply, so that it goes smooth ? Can u give me a picture of the knob you use ? -
Hi AG
I've seen some lens specially made for luxion 1 watt LED's at
http://ledsupply.com/l2-op-025.php . What is your suggestion on this ? -
Thanks for the value AG but is it a standard value that we get ? . I feel ante's selection is a good one but do you call them a multiturn pot ? or does it have a specific name ??? ?
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Hi AG
So is the 100 Ohms pot fine for the fine tune . What should be the value if i need to get a fine tune of one volt ? -
hello esp1
Actually i just guessed with no practical calculations . But since u say its going to be fine i just have to try it out . But since AG said you should reduce the value of the existing pot as well, I am confused . -
Thanks a lot AG , I was about to wind up after shaftons reply . Will this changes be sufficient ?
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I have made the 0-30 volts lab power supply which is there on this site . I want to know if it was possible to add a FINE TUNE provision for accurate selection of the O/P voltage . Please help me .
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Hi AG
I connected a 11 Ohms resistor as the load . I noticed that the o/p voltage of the lm317 regulator was 3.6volts dc when the input voltage to the regulator was varied from 7.82volts dc to 17volts dc . The lm317 is cooler then before now . Is this enough AG ??? as the forward voltage for the led is 3.48 volts dc ? -
Hi AG
Then I will have to use a 9 volts 500mA step down transformer. Will that give enough voltage for lm317 ? -
Hello AG
The LED forward voltage i measured is 3.48volts . So it wont be sufficient na ? -
Hi AG
So I would have to use a 6 volts stepdown 500mA transformer,bridge and a filter which would give an o/p voltage of 8.64 volts dc across the filter capacitor to reduce the voltage to lm317 ? -
Hi AG
What should be the resistor value instead of 3.9 Ohms if i put only one LED ? -
Hello AG
Could these heat sink be sufficient for the regulator ? I first used PI49 and found the regulator over heating .
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Hi AG
Since i am weak in electronics i am getting confused . In the ckt the 3.9 Ohms is connected from o/p to adjust terminal so when the LED's are drawing 350mA current, then is the current flowing through the 3.9 Ohms resistor ? Or from where is it drawing current ? -
Hello AG
One more doubt before connecting the load, should the 3.9 Ohms resistor also be 2 watt ? -
Hello AG,
Can I put a 25 ohms resistor in instead of the led's to see the voltage across it ? If so should it be a 2watt ? -
Hello AG
The o/p of the lm317 is 15.45 volts(open voltage). Will it harm the led's . -
Hi AG
Which is the ideal resistor to be used in series with the LED to find out its exact forward voltage ? I have a 6volts battery as a source . -
Hi AG
Thanks a lot for that . What will happen if the input voltage rise beyond 230 volts, as i measure 17.3 volts at 1000uF capacitor . And what is the calculation for finding out the o/p voltage of the lm317 AG ? -
Hi AG,
So the value of the resistor is 1.2ohms ? -
Hi AG,
Your 390 ohms resistor reduces the LED current to only 1.25V/390= 3.2mA which is way too low. 3.9 ohms would regulate the current at 320mA to 330mA.
Should i take tho o/p at pin 2.
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