Automatic 40 Watt LED Solar Street Light Circuit Project - Part-2

In the previous article we discussed the charger controller, the battery high/Low controller and the light sensor sections of the proposed 40 watt automatic solar street light system circuit. This page will show you the making procedure of the PWM controlled LED module circuit.


The circuit shown below represents the LED lamp module consisting of 39 nos. 1 watt/350 mA high bright power LEDs.

The whole array is made by connecting 13 number of series connections in parallel, consisting of 3 LEDs in each series.

The above arrangement of LEDs is pretty standard in its configuration and does not focus much importance.

The actual crucial part of this circuit is the IC 555 section, which is configured in its typical astable multivibrator mode.

In this mode the output pin#3 of the IC generates definite PWM wave-forms which can be adjusted by setting the duty cycle of the IC appropriately.

The duty cycle of this configuration is adjusted by setting P1 as per ones preference.

Since the setting of P1 also decides the illumination level of the LEDs, should be done carefully to produce the most optimal results from the LEDs. P1 also becomes the dimming control of the LED module.

The inclusion of the PWM design here plays the key role as it drastically reduces the power consumption of the connected LEDs.

If the LED module would be connected directly to the battery without the IC 555 stage, the LEDs would have consumed the full specified 36 watts.

With the PWM driver in operation, the LED module now consumes about 1/3rd power only, that is around 12 watts yet extracts the maximum specified illumination from the LEDs.

This happens because, due to the fed PWM pulses the transistor T1 remains ON only for 1/3rd of the normal time period, switching the LEDs for the same shorter length of time, however due to persistence of vision, we find the LEDs to be ON all the time.

The high frequency of the astable makes the illumination very stable and no vibration can be detected even while our vision is in motion.

This module is integrated with the previously discussed solar controller board.

The positive and the negative of the shown circuit needs to be simply connected to the relevant points over the solar controller board.

This concludes the whole explanation of the proposed 40 watt automatic solar LED street lamp circuit project.

If you have any questions, you may express them through your comments.





Assembled prototype available for INR 5000/- All Inclusive, with all part numbers intact.

Parts List

R1 = 100K
P1 = 100K pot
C1 = 680pF
C2 = 0.01uF
R2 = 100 Ohms
T1 = TIP122
R3----R14 = 10 Ohms, 2watt
LEDs = 1 watt, 350 mA, cool white
IC1 = IC555

In the final prototype the LEDs were mounted on special aluminum based heatsink type PCB, it is strongly recommended, without which the LED life would deteriorate.




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181 comments

comments
October 3, 2012 at 9:41 AM delete

hi,
great circuit, which consumes 1/3rd power.can we further reduce power consumption by varying P1 without affecting vision?or is the max? can we substitute 2W resistor with appropriate diodes for reducing heat loss to some extent?
thanks & regards
vineesh kodambattil

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October 3, 2012 at 10:37 AM delete

Hi, Thanks!

I had used a fixed 39K resistor in the prototype, but i think P1 would enable a zero to max power to the LEDs.

Since the battery voltage is not fixed, resistors are better suited instead of diodes.

Regards.

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menanti
October 19, 2012 at 11:29 AM delete

Hi,
I like it. Just one question, it is possible to reduce or add the led? If yes, it is need to change the circuit?
Thanks,


Regard

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October 19, 2012 at 12:35 PM delete

Hi,

You may reduce the number of series for reducing the number of LEDs, no change would be required in the circuit.

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Menanti
October 19, 2012 at 2:28 PM delete

Thanks, i'll try. The component ready, but could not find aluminium base heatsink pcb....I just have 9 led with heatsink,
so no need to that one. Thank for you fast reply...

Regards,

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Menanti
October 21, 2012 at 6:31 PM delete

Hi, i've done with it. It works, thanks a lot.
I have few questions,
1. How much the current and the voltage value before connected with resistor and the 3 series led?
2. It is possible to use lower voltage? i.e. 6 volts? If yes, which components should change/modify?
3. Is this design more efficient than the design you've made for emergency light?
4. If its more efficient, can you made a design of automatic emergency light using this design?
Thanks for your kindness, GBU.

Regards

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October 22, 2012 at 10:32 AM delete

1) sorry, I did not understand your first question.

2) with 6 volt supply you will need to connect a single LED in each series, rest everything will remain as it is.

3) This design is more efficient because it's PWM based.

4)This design may be simply integrated with my previous emergency light circuit for improving it.

Regards.

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October 24, 2012 at 4:44 PM delete

Hi, Dear Mr. Swagatam . I have 19.5v/4.5A SMPS - How can I connect 2X5W LEDs with 555 and TIP 122 system

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October 24, 2012 at 8:24 PM delete

Hi Dear Kapila,

19.5 will be too high for a 555IC so you will have to add a 7812 IC for dropping the voltage then use the above circuit just as it is shown.

The LEDs may be connected in series with a 10 Ohms resistor.

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October 24, 2012 at 10:27 PM delete

Thank you dear Swagatam.

Now I have 2 problems
1-is your 1 Watt joule thief LED circuit, If LED will takes 350mA when it's working... what is the fully discharge time for 1.2V/2000mA NiMH battery?
2. I have too many Batteries, cos I'm a Photographer. So I need make some pro: type LED portable Studio lights. I have 100pcs 1 watt LED-cool white. Otherwise using 6V/6A sealed type lead acid battery. I have both. Please Help me.
Thanks and Regards.

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October 25, 2012 at 8:15 AM delete


Hi Kapila,

In the joule thief circuit the LED is not consuming 350mA, rather may be only 100mA and even at this rate the cell may become flat within 10-15 minutes.

Using 6V/6ah battery would be good, you may make the circuit shown in the above article. You will have to make many series of a single LED with a 15E/2watt resistor each, and connect them all in parallel.

Regards.

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October 25, 2012 at 9:15 AM delete

Hi,Dear Mr Swagatam
Thank you so much


Regards

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Anonymous
October 27, 2012 at 12:49 PM delete

Dear Swagatam,

Very good job. I tried & got success. Now i have a question

If I want to drive it on 230VAC (transformer less) then what type of modification is to be needed.

Ray

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October 27, 2012 at 1:10 PM delete

That's Great!

This circuit will require at least 1amp current so a 12v/3amp SMPS power supply would be the only option for operating this circuit.

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October 29, 2012 at 11:56 AM delete

hi
smps's power supply has 12v out put .can we use this 12v directly to leds with proper resisters.i mean excluding ic555 and transister.?
an if we use then whats will be the benefit

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October 29, 2012 at 12:25 PM delete

Hi,

yes, you can do it by connecting the shown LED bank common points to the respective positive and negative outputs of the SMPS power supply.

The smps should be rated at 3 to 5 amps.

There will be no benefit, rather there will be loss of power.

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Anonymous
October 31, 2012 at 11:24 AM delete

Thanks for your reply...

Please provide the simple LED Driver/SMPS circuit which can run both AC and DC....

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October 31, 2012 at 5:26 PM delete

You may try the following circuit:

http://homemadecircuitsandschematics.blogspot.in/2012/03/how-to-make-simple-12-v-1-amp-switch.html

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Anonymous
November 15, 2012 at 8:26 PM delete

can i connect this to a 7amp 12v battery ?

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November 26, 2012 at 2:06 PM delete

Hi Swagatam,

Is the above PCP shown in your construction "aluminum based heat sink type PCB"? if not how will it look like. please help.

Regards
Nagaraj

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November 26, 2012 at 2:43 PM delete

Hi Nagaraj,

No it's an ordinary PCB, see the pic here you will find the heatsink type pcb with mounted LEDs:

http://4.bp.blogspot.com/-CCBvWrOXAaM/UGsbaQHJP_I/AAAAAAAAAxM/dIzHEuF9uwY/s1600/40%20watt%20solar%20street%20light%20prototype.png

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November 28, 2012 at 2:59 PM delete

hi swagatam,

1.)shall i directly plug this circuit with 12v/7amps battery or i have to include any diodes, or resistors or any other else?
2.)i bought a NE555N IC as IC1 is it correct?
3.) and please recommend me a battery charging circuit for 12v/7amps battery by 12-012v/3amps transformer with overload protection.

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November 28, 2012 at 5:29 PM delete

Hi Deepan,

Yes you may plug the circuit directly with the battery but be carsful of the polarity, wrong polarity will instantly damage the IC.

NE555 is OK.

You may refer the second circuit in this article for battery charging:

http://homemadecircuitsandschematics.blogspot.in/2012/11/making-40-watt-led-emergency-tubelight.html

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November 30, 2012 at 8:32 PM delete

Hi swagatam, today i purchased this circuit's parts with some changes, is it OK?
1)INSTEAD OF C1 = 680pF I BOUGHT 2A682K POLYSTER
2)T1 = TIP122 IS NOT AVAILABLE IN MY LOCALE MARKET. SO, PLEASE RECOMMEND ME AN ANOTHER ONE INSTEAD OF THIS.
3)R3----R14 = 10 Ohms, FOR THIS YOU RECOMMENDED ME(150 OHMS INSTEAD OF 10 OHMS ) IN MY OLDER COMMENT, BUT I BOUGHT 180 OHMS INSTEAD OF 150 OHMS BECAUSE OF NO STOCK.

DO I NEED TO CHANGE ANYTHING??

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December 1, 2012 at 5:26 PM delete

Hi Deepan,

I am sorry you'll have to use the parts just as shown in the diagram, any other equivalent might not give proper results.



I am not very sure what 682K means, I'll have to confirm it.

For 1 watt LEDs you will have to use 10 Ohms only.

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December 7, 2012 at 10:14 PM delete

Hi Swagatam,
While making the list of components to be purchased, i came across C2 = 0.01uF, here i need to know what is the voltage of the capacitor need be. I am getting confused on the value. is there any alternate to this value.

Please help.

Regards
Nagaraj

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December 8, 2012 at 9:31 AM delete

Hi Nagaraj,

It's a ceramic disc capacitor rated at 50 volts.

It's also called 103 capacitor. There's no alternate replacement for it, sorry.

Regards.

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December 19, 2012 at 12:35 AM delete

dear swagatam, what is C1 = 680pF??

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December 19, 2012 at 12:45 AM delete

dear swagatam,
how to fix the P1?
100k pot has 3 pins, i connected the pin1 with R1 and Pin3 with C1 and where i have to connect the pin2?

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December 19, 2012 at 9:57 AM delete

Dear Deepan,

C1 is a disc ceramic capacitor.

Join the center pin of the pot with any one of the outer pins....

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December 19, 2012 at 7:19 PM delete

Dear Swagatam,
I had purchased one white LED strip and used a portion for my fish tank. The remaining strip, i would like to use it as normal lighting purpose. so as it has its own resistor, i would like to use the above PWM circuit attached to it. I have cut the strip which has 9 LEDs each in 14 bits and pasted it in a card board. i can use them either in series or in parallel connection as i have not connected the ends. So kindly help me with any modifications to accomodate the strip LEDs.

Regards
Nagaraj

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December 20, 2012 at 8:47 AM delete

Dear Nagaraj,

You shouldn't have cut them, you could have used the whole strip in a straight line over your rooms wall.

anyway, you may now restore the connections back by joining the strips by wire pieces, join them from where you cut them. You will find two copper dots after each series of 3 leds, connect wire from these dots and join all the strips in parallel with their respective copper dots.

Regards.

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December 20, 2012 at 3:30 PM delete

Dear Swagatam,

My request was that what modifications in the above PWM circuit should be done to accommodate the strip LEDs i have.

Regards
Nagaraj

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December 20, 2012 at 8:27 PM delete

No modifications will be required, connect the strip across the shown points, i.e across positive and the collector of the transistor.

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Anonymous
December 30, 2012 at 5:11 PM delete

Hai swagatam,

hai sir can I use tip112 instead of tip122

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January 2, 2013 at 9:55 AM delete

Hi Swagatham,

Happy belated New Year greetings.
I just got one doubt. can i use the normal 5 mm LEDs with the above circuit. Because of the principle stated above, I thought that i can utilize the above circuit to power normal LEDs and get more output by drawing less power. Kindly suggest any modifications if any in the above circuit. also with this how many LEDs can be connected (maximum) and how.

Regards
Nagaraj

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January 2, 2013 at 7:26 PM delete

Hi Nagaraj,

Wish you the same!

Yes you may 5mm LEDs, you will only have to change the series resistors to 150 Ohms, no other modifications would be required.

You can connect upto 399nos 5mm LEDs

Regards.

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January 10, 2013 at 10:22 PM delete

Hi Swagatam,

Regarding the strip LED, I got one more query to be clarified. As stated above, I have cut the strip LEDs consisting of 9 LEDs series and connected parallel consisting of 14 strips and pasted it in a card board. Now i need to know as to what power will it consume without using the above PWM circuit.

Regards
Nagaraj

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January 11, 2013 at 2:16 PM delete

Hi Nagaraj,

Normally in strip LEDs, each series is made of 3 LeDs and a resistors, these series are then connected in parallel over the entire strip.

9 LED means, 3 series strings connected in parallel.

if we assume 20 mA for each series, one 9 led strip will consume 60mA.....and 14 of them in parallel would consume 60 x 14 = 840mA

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January 21, 2013 at 10:05 AM delete

dear sir ,
how many LEDs can we connect while using 12v 7.5 ah battery

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January 21, 2013 at 1:37 PM delete

dear jabert,

around 20 leds (1 watt) ideally...

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January 27, 2013 at 8:49 PM delete

Dear Swagatam,
Nagaraj again here. Construction of the above circuit went well with one hitch (instead of C2 = 0.01uF ceramic capacitor, I have put in place polyester capicator of the same value 103/50v). will this hinder the working of the circuit?. Next, I am planning to use aluminium plate instead of aluminium based PCB as suggested. Then, I am getting only 10 v at the output. Is this ok. or what might be wrong. Also the resistor R2 gets heated up very fast.

Kindly suggest me the necessary measures so as to make this circuit functional.

Regards
Nagaraj

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January 28, 2013 at 9:09 AM delete

Dear Nagaraj,

any type 103/50v will be ok.

I didn't understand how you would be using an aluminum plate for mounting the LEDs???

what is power supply...a 12V or 10V???

R2 should not become hot, only the LED resistors might become a little hot.

Regards.

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January 28, 2013 at 5:52 PM delete

Dear Swagatam,

To test with, initially I am using the above said strip LEDs. So the power supply is 12v 2A power supply.

Also, due to non availability of heat sink based PCB, I am planning to mount the LEDs on to the aluminium plate duly tied to the plate. I already have soldered the LEDs on to a readymade heat dissipator aluminium plate (small one which was given to me when purchasing the 1 watt LEDs) then these will be tied to the aluminium sheet. Will forward the photo of it when finished. I am going to use the SMPS of 12v 5A as suggested by you.

Now coming to my above query, kindly help me in finishing this project.

Regards
Nagaraj

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January 28, 2013 at 8:51 PM delete

Dear Nagaraj,

if you do everything as suggested in the article, nothing should go wrong and the LEDs should light up brightly immediately.

The voltage at pin#3 will vary in response to the pot adjustments.

R2 in any case should become hot.

Regards.

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January 28, 2013 at 9:06 PM delete

R2 should NOT become hot in any case....

for getting maximum light, you can eliminate the 555 circuit and connect the smps directly to the LED board assembly.

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January 29, 2013 at 11:49 PM delete

Dear Swagatam,
I really tripple checked the diagram and my construction and they are one and the same. If I omit the 555 circuit, then the purpose of me constructing this project itself is shelved. my intention of going for this project is your comment on the working (With the PWM driver in operation, the LED module now consumes about 1/3rd power only, that is around 12 watts yet extracts the maximum specified illumination from the LEDs.)

I need to know what should be the voltage at the collector of the transistor T1. Based on your reply, this project will be ready in a day or two.

Regards
Nagaraj

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January 30, 2013 at 9:25 AM delete

Dear Nagaraj,

I did not measure any voltages in my prototype, everything worked perfectly as intended. Only the transistor was getting hot so I mounted it on a suitable heatsink.

As mentioned earlier the output voltage would vary in response to the position of P1.

Regards.

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February 3, 2013 at 3:11 PM delete

Hi Swagatam,
As asked by one of the followers above for reducing the number of LEDs and for that you have said that one can reduce the LEDs, my query is can we reduce the amperage of the power supply. I am planning to have around 12 LEDs with the above circuit, so can I have the power supply of 12v and 2A?

Regards
Nagaraj

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February 8, 2013 at 5:18 PM delete

Hi Swagatam,

I have constructed the circuit as per the instructions mentioned above. Now the LEDs are not lighting up. I have checked all the connections and they are fine without any mistakes. kindly help me to troubleshoot the problem. The power supply used is 12v 5A with the PWM circuit and 39 1 watt LEDs.

Regards
Nagaraj

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February 8, 2013 at 8:42 PM delete

Hi Swagatam,

Nagaraj again. I have checked the voltage across the resistors and it showed 12v and again when I checked across the collector of transistor, I am getting 11.5v. Also the wiring are perfect as per the diagram and still once again I checked all the connections of the PWM circuit but in vain. Every thing is perfectly done. But still the LEDs are not glowing. On the comments above, one person has been successful in building this. can I have his mail ID so that I can request him to check out the voltage at various points. Somehow I need to solve this mystery.

Regards
Nagaraj

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February 8, 2013 at 8:52 PM delete

Hi Nagaraj,

It would be difficult for me to troubleshoot because my unit worked perfectly at the first instant.

short the collector/emitter of the transistor temporarily, and check if the LEDs iight up or not.

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February 9, 2013 at 12:07 PM delete

Hi Nagaraj,

short the collector/emitter of the transistor temporarily, and check if the LEDs iight up or not.

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February 15, 2013 at 11:59 AM delete

hi swagatam

can we use 10 led's instead of 40

and in part one of this project, what is watts of solar panel??

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February 15, 2013 at 9:07 PM delete

Hi Rajavardhan,

9 leds can be used, because the figure should be a multiple of 3.

a 100 watt panel would do.

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March 2, 2013 at 1:44 PM delete

Dear Swagatam,

At last I have made it. Actually there was dry soldering at one point. Now as per your suggestion, the LEDs are glowing after shorting the collector and emitter. Now, my query is of the functioning of this circuit. will it work as per the above theory. will it save power as stated above. or is it just glowing in the normal way. And is it possible to keep the collector and emitter in short for long time. kindly help me.

Also I am not sure whether we can post the photos of the projects for any clarification or not in this site and that is why I had to get in touch through mail.

Henceforth, my sincere request to you is that kindly keep some points for all your upcoming projects/circuit ideas in case of any necessary troubleshooting if required so that everyone will be benefited from this.

Regards
Nagaraj

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March 2, 2013 at 9:24 PM delete

Dear Nagaraj,

My assumption was wrong, don't incorporate the circuit because though it will reduce current consumption, it will also result in some loss of brightness.

Connect the led along with its resistors directly to 12V supply.

And yes, you may need to reduce the resistor values to 6 ohm for optimum brightness.

Your shown heatsink size looks inadequate to me....you might need a lot bigger than that....because the LEDs will get very HOT.

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March 2, 2013 at 9:26 PM delete

you can upload the pics to www.imageshack.us and give me the link, i'll do the rest:)

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March 3, 2013 at 11:24 AM delete

Dear Swagatam,
I, once again highly appreciate your prompt reply.

The main purpose of me building this circuit is only because of the reduced current consumption. I do not mind about the loss of brightness (hopefully not much) when compared to loss of current. So please suggest me how to go about it from here as I have briefed about the problem in detail( the circuit works only when I short the collector and emitter).

I will have a bigger heatsink as suggested by you.

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March 4, 2013 at 10:22 AM delete

Dear Nagaraja,

The 555 circuit is absolutely correct, as you can see in the given image it has been tried by me successfully, and the prototype sold to one of the interested customers.

Check the output of your circuit, it should generate variable voltage when the pot is turned.

Or may be your TIP122 transistor is faulty.

check these you will definitely be able to trace out the hidden fault.

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March 4, 2013 at 10:25 AM delete

pin#2 of the IC is connected to pi#6 only, and nowhere else....

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Anonymous
March 7, 2013 at 1:20 AM delete

On October 21, 2012 Menanti (above) asked if it was possible to use 6 volts to operate this circuit and what modification is required.
And if this design is more efficient than the design you've made for emergency light?
You answered that 6 volt supply one need to connect a single LED in each series, rest everything will remain as it is. So would it be okay if I connect a solar panel Rated volt 9v, Open circuit volt 11V, short circuit current 0.38A) as input volt?
You also mentioned that this design may be simply integrated with my previous emergency light circuit for improving it. Could you please elaborate how to integrate this design to your emergency light design? Simply remove inductor L and connect leds to 10ohm 2Watt resistors? Or what else do I need to change?

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March 10, 2013 at 7:08 PM delete

Dear Swagatam,

I have started to reconstruct the above circuit from the begining and now, I need your help to clarify me with a few points as below:
1. If I am right, the center tap and one end of the pot is to be shorted and connected to pin 6 of IC.
2. As you have stated in your reply above, should I reduce the values of the resistors (R3-R14) to 6 ohms instead of 10 ohms?.

Regards
Nagaraj

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March 10, 2013 at 9:29 PM delete

Dear Nagaraj,

1) yes, that's correct, also pin2 and pin6 must be shorted.

2) to get 100% illumination, you may reduce them to 6 ohms 2 watt

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Anonymous
March 12, 2013 at 7:19 AM delete

Second part calculation is the part I don't get it....How did you calculate 10 ohms in the first place and now 6 ohms?? Could you explain this to me, please? Thank you. I understand how 2 watts came from.

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March 12, 2013 at 9:06 AM delete

10 ohms is actually not correct, but it will give relatively good illumination with lower heat generation.

6 ohms is optimal value, it will give very high illuminations but will also generate a lot of heat, and will necessitate bigger, finned type heatsink.

watts = 9.9 x .3 = 2.97watts, however a 2 watt does the job

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March 20, 2013 at 3:11 AM delete

Hi Swagatam, I have a 12v 5amp SMPS and going to connect this circuit (bypassing your part 1 section) but I would like to make the lights auto turn on at dusk and off at dawn. Probably LDR is the way to go but where do I connect the LDR in the circuit above or do I need to modify the circuit? Please help.

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March 20, 2013 at 3:41 AM delete

hello Swagtam,
I am trying to build a project which automatically control the lighting of a room, and i planned to use led's for that in combination of ldr sensors and ir sensor and powering it with a solar panel using a rechargeable lead acid battery as i am new to try this in practical can you help me my project. its my final year be project

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March 20, 2013 at 7:27 PM delete

Hi Maya, you can eliminate the 555 section in the above circuit design.......use only the LED strings with the resistors, and connect the assembly to the smps supply via the relay contacts of the LDR sensor circuit that's shown in the below given link:

http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-light-activated-day-night.html

The LDR circuit in the above link should be also powered from the same SMPS suuply

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March 20, 2013 at 7:36 PM delete

Hello Rachit,

Please provide your requirement in full details, write the stages elaborately,.....I'll surely design it for you, and also help you to build it successfully..

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April 2, 2013 at 3:47 PM delete

Hello can i use br circuit for 12v dc instead of smps

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April 2, 2013 at 8:57 PM delete

any DC 12V source at 3 amp can be used for operating the circuit.

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April 6, 2013 at 2:15 PM delete

Hi Swagatam ,you have got one more fan ,

I have one 20 Watt led(Operates on 12V) What would you recommend should i directly connect it to a 12V , 2amp adapter or use this circuit.....

I have observe by connecting two 10watt led parallel with 12V , 2amp adapter it works smooth but problem arises that the heat sink become pretty much hot , and consume the rated power....

I think your circuit for PWM is much useful and exactly the same, one i was looking for ,perhaps it reduce the power loss by allowing only 1/3rd of the power so that the heat sink will remain in moderate temperature and the led will work saturated.......

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April 6, 2013 at 5:05 PM delete

Thanks banoo!

Initially I thought that we could fool our eyes by illuminating the LEDs via a frequency, which would allow only half the consumption, and yet due to persistence of vision create an impression of full illumination, but later I understood that it wasn't feasible , our eyes can detect the difference, and a directly connected LED would produce better results than a PWM light.

So the over all response would be the same.

I would suggest you connect them directly to the power supply via a current limiting resistor. Add adequate heatsink along with a current controlled circuit which would prevent the LEDs from a run away situation.

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April 7, 2013 at 9:37 AM delete

Hello Swagatam,
Thank you kind sir, for posting this very useful circuit design. If you could find the time to answer, I do have a question. I would like to modify your circuit to utilize four 1w leds, in two series of two. I would also need to vary the frequency from around 5-100hz. This frequency range is an estimate and not crucial at this time. Could you please suggest an appropriate modification and component values? Thanking you in advance.

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April 7, 2013 at 11:47 AM delete

Hi SSBlade,

Thanks!

with two leds, you would require 18 ohm 1 watt resistors in each string at 12V.

use 0.22uF for the capacitor, that's all, no further changes would be required.

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April 7, 2013 at 11:15 PM delete

Swagatam,
Your timely response is much appreciated, and your skill is very evident. I will make the suggested modifications. My purposes for this, is to build a small, yet bright stroboscope for monitoring moving parts. I require a short duty cycle for clarity. Will I need to modify the value of R1 to obtain this?
Regards, SSBlade

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April 8, 2013 at 8:53 AM delete

Thanks SSBlade,

R1 can be replaced with a fixed 10K resistor and P1 with a 100 pot, this would roughly give you 50 to 100% duty cycle control.

The frequency may be adjusted by altering the capacitor value as per the required specifications.

Regards.

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April 9, 2013 at 1:33 AM delete

AS I DRIVE A LOAD OF 3WATT CONSISTING OF 25 PAIR (2 LED IN SERIES),EACH 1WATT LED,USING 6V 4.5AH BATTERY.
1.HOW CAN I INCOPERATE THIS CIRCUIT ACCORDING TO MY SPECIFICATION.. WHAT VALUES SHOULD I HAVE TO CHANGE..?
2.MY LED LIGHTS UP VERY BRIGHT IT TAKE AROUND 9 HOURS TO GET OFF. HOW CAN REDUCE THE BRIGHTNESS OF LEDS. HOW CAN INCREASE THE EFFICENCY OF CIRCUIT.. SO IT WOULD EXTEND UPTO 12 TO 14 HOURS..

REPLY ASAS
THANKYOU

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April 9, 2013 at 8:44 AM delete

so many LEDs will not work with 6v 4.5ah battery.

reduce the number to 10, (5 strings with 2 leds in each string)

no modifications would be required, use the same circuit as shown in the above diagram.

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April 9, 2013 at 3:41 PM delete

Can i control the brightness of leds with ldr and please give me link also
thanks

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April 9, 2013 at 7:17 PM delete

i'm sorry the led is not 1watt its a straw hat white led 3v,20ma rating around
1/4watt. so if i connect two led in series it will not require any resistor in series(practically)..
thankyou very much for early response.

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April 9, 2013 at 9:00 PM delete

with 20mA it would be possible to add 25 strings of 2 each.

yes no resistors would be required.

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April 10, 2013 at 1:04 PM delete

Please provide full description of your requirement.

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April 12, 2013 at 10:21 PM delete

I am little confused now...maybe much more confused b/c one of your article on how to calculate how many leds to use suggests the voltage should be 25% higher than Leds Vf and if jp8rock wants to use 6V battery (Vs), how can you even have 2 leds (6.6Vf) in each string since high power led has average 3.3v (Vf) that already makes higher (not considering extra 25% for the full brightness) than Vs. Let's say you are considering not full brightness, first does it even lit the led with under volt? Second, if there is no modification what about the 10 ohm resistors in your original circuit, doesn't that even impact to operate?
I thought you calculate the required resistor:
(Vs-Vf)/If = (6-(3.3x2))/0.7 (if it is for 3W led)
That doesn't add up 10 ohm!! I am lost right here.

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April 13, 2013 at 8:03 AM delete

The 3.3V is not a fixed parameter, a white LED would start illuminating even at 2.6V where it will be quite dim, and may be extended upto 3.6V where it will super bright. So it depends on the user how much light he wants to derive from it.

At 3V also an LEd would produce good amount of light, at 3.3V it would be still better, after that it starts getting risky, and that's why we introduce a resistor.

When I said 25% more it was referred to the level where the LED just begins illuminating that's around 3V.

At 6V two LEDs can easily share 3V each with reasonable illumination and because the voltage is within the safe forward voltage limit of the LEDs we won't require a current limiting resistor, the formula would give you a "zero" result, meaning no resistor required.

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April 21, 2013 at 8:09 PM delete

Hi Swagatam,
Nagaraj here again. As i had requested above regarding the strip LEDs, after connecting them to my fish tank, now I have small bits of them, from one strip (3 LeDs and a resistor)to maybe 5-7 strips. So now i need to know as to what is the supply voltage they require to illuminate. Should i still use 1 amp power supply or can i reduce the amperage of the supply. I intend to use them in small rooms so that they are not wasted. If possible, can you help me with the power supply without using transformers.

Regards
Nagaraj

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April 22, 2013 at 10:05 AM delete

Hi Nagaraj,

you may keep increasing the strips, keep a watch on the DC supply voltage, once it begins dropping below 12V would mean it has reached its limit and it wouldn't be good to connect anymore LEDs to the adapter....if you still want to increase the LEDs you could go for a higher rated power supply.

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April 22, 2013 at 10:08 AM delete

sorry i didn't read you question carefully, i thought you wanted to use a single power supply for all the LEDs....for small bits, you can go for 500mA adapter........don't worry about power wastage it won't happen because the LEDs will only consume what it requires not more than that.

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May 3, 2013 at 4:28 PM delete

Hi Swagatam

My Question is related to same project i discussed previously on this comment page...
as I Incorporated PWM controlled LED module circuit in my solar controller circuit with an efficiency(high) 80%.
1.How can i calculate the Power consumed by led(3watt).
2. i'm charging my lead acid battery 6V 4.5AH with a 3 watt panel(Voc = 10v and imax = 0.370amp)
which will theoritically takes around 9hours for charging the battrey full..
but in my circuit i'm using the direct charging of the battrey through solar panel via schottky diode 1n5408(3amp diode) with a charging indicator led..

problem is that on full sun day i measured the volatge around panel with circuit connected is 7.2V but the volatge after the diode drops to 6.4V.. which means it will not going to charge battery full in this case so my question is that if i want to replace this 3amp diode with some safe value which will be capable of protecting panel then it would be what value.. so that voltage should not fall below 7.2V(ie the charging volatge) or should i replace the panel with 5watt panel as it will decrese the charging time by 3 hour or you tell tell me the solution for the problem..

reply asap
Thankyou


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May 4, 2013 at 9:34 PM delete

Hi JP8rock,

the power can be calculated by measuring current consumption and then multiplying it with the LED operating voltage.
The current can be checked with a multimeter set at DC current range and in series with the positive of the supply.

schottky diodes are the most efficient and drop minimum voltage, so I am afraid there isn't any other device which would replace it.

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Anonymous
June 24, 2013 at 11:27 AM delete

Hi Sir Swagatam
Many many thanks for circuit, But I have a question
can U explain how convert this circuit to use for 3v 20mA LEDs.
thank
I,m Aruna

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June 24, 2013 at 8:56 PM delete

Thanks Aruna,

For 3V 20ma LEDs make all the LED resistors to 150 ohms, 1/4 watt and the transistors can be changed to 8050 or 2N2222.

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Anonymous
June 26, 2013 at 6:50 PM delete

Hi,i have the following questions.

(1)I would like to have the LED lamp's brightness that equals to the brightness of a fluorescent lamp, what power and current ratings of the LEDs i need to get?

(2)Does the 555 timer IC needs to be put on a heat sink too?

(3)I am using a 12VDC,40Ah car battery to run the lamp so the voltage might spike to 15V. Can the lamp handles 15VDC?

Thanks alot.
SunBoy.

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June 27, 2013 at 11:30 AM delete

Make the LED/resistor bank as given in the above article and connect it directly to a 12V 2amp smps, IC555 stage won't be required.

The LEDs will need a very good heat based PCB.

However for current control and voltage protection you use the following circuit:

http://1.bp.blogspot.com/-Q2nCJ3sN8eg/UKkQ-9SL_sI/AAAAAAAABeM/yykjA1N8GDg/s1600/3%20watt%205%20watt%20led%20driver%20circuit.png

the 400 ohm will need to be changed to a different value.

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Anonymous
June 28, 2013 at 10:47 AM delete

Hi, can i make this on a normal stripboard?

Can use thicker wires to connect the LEDs so it works without heatsink?

Thanks.

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June 28, 2013 at 3:25 PM delete

No that won't work, the LEDs will generate a lot of heat so a heatsink is very much essential.

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July 11, 2013 at 4:42 PM delete

hey,

let me know is the output voltage and current remain same if input is 10vdc to 14 vdc?

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July 11, 2013 at 7:48 PM delete

No! what are you trying to make?

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Anonymous
July 17, 2013 at 9:05 AM delete

very nice that you are sharing wonderful information. well done.

Your circuits are customized therefore requires customized PCBs also.

Can you also help to get the PCB that you have mentioned in your blogs.


Regards
Neeraj Mehra

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July 17, 2013 at 11:19 AM delete

Thanks!,providing pcb layouts would make things difficult and time consuming for me....so I am sorry....

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August 28, 2013 at 8:39 PM delete

Hi Sir, if I do not have solar panel. Is it possible to use this circuit on direct 220VAC? What component do I need to change or what modification is required? Kindly advised. Thanks a lot.

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August 29, 2013 at 9:30 AM delete

Hi Unknown, yes it would be possible but only after dropping and rectifying the mains voltage to 30V.

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August 29, 2013 at 10:28 AM delete

Hi Sir, thanks for the explanation. Would it be possible to include a schematic how to do it as I am pretty much a newbie in electronic and are still learning. I want to use the circuit above to power up some of the 1W led bead that I have using AC cause I do not have a proper place for solar panel here.

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August 30, 2013 at 10:43 AM delete

I am sorry it should a 12V DC input that's required, not 30V.

You can simply buy a 12V 2amp SMPS unit and connect it with the above circuit.

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September 6, 2013 at 9:03 PM delete

Helo sir,
Can we put 2n3055h in the place of tip122.
I had a smps having 18v 3amp output can it is used to increase the no of leds in each string with adding 7812 for ic vss

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September 6, 2013 at 9:58 PM delete

Helli sir,
Can 2n6292 transistor work in place tip122

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September 7, 2013 at 2:26 PM delete

Hi Avijeet,

2N3055 will work, not sure about 6292, you can compare the datasheet with TIP122 to confirm.

Yes the trafo will be ok, use 7812 for the IC555, and connect the bridge output directly to the LEDs but only after calculating the no of LEds in the strings and the individual resistors appropriately...I hope you know how to do it.

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September 7, 2013 at 6:15 PM delete

Thanks for ur reply sir,
I had checked datasheet i think it can be applicable. i m posting the link
http://www.alldatasheet.com/datasheet-pdf/pdf/2497/MOSPEC/2N6292.html

Please take a look on it
Thanks

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September 8, 2013 at 9:43 AM delete

Yes it will do, I have checked it.

Thanks!

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October 2, 2013 at 11:48 PM delete

when i connect the led lamp directly to a 12 v power supply at first the led glow at full brightness for a second. but then becomes dim. if i bypass the 10 ohm resistor then they glow at full brightness. what could be the problem. could it be the limited supply of current from my power supply (may be less than 350mA). please help

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October 3, 2013 at 9:58 AM delete

The resistor in the above diagram is well calculated, so you shouldn't have bypassed them , that would cause weakening and damage to your LEDs.

I have mentioned in the artice that you would need a 2amp smps as power supply, did you use a 2amp supply??

If not then it might be due to low current.

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October 3, 2013 at 5:03 PM delete

thanks. problem solved. my supply was not upto required rating.

i have one more question. i connected led lamp directly to the 12 v battery without 555 timer module. current consumption was 1.24 A that makes 1.24 * 12 =14.88. what is the purpose of pwm circuit if current consumption without it is 1.2 A max? and can i connect 4 or 5 LEDs in a row without any change in led lamp circuit??
thanks.

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October 3, 2013 at 7:15 PM delete

Great!

No problem, you can connect them directly also. The 555 circuit only provides an option of dimming and power saving.

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October 4, 2013 at 7:58 PM delete

if i use a 100 watt led, connecting every 10 led in parallel (as you have connected 3 led in parellel per column). is it possible? if yes then what changes should be made. if not then what no. of max led can be used with this cirruit(i mean lm338 providing 4 Ampere max) thanks.

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October 5, 2013 at 10:18 AM delete

In the above circuit, 3 LeDs are in SERIES in each string.

LM338 will not support even a single 100 watt LED, you will have to use the following design for it:

http://homemadecircuitsandschematics.blogspot.in/2011/12/make-hundred-watt-led-floodlight.html

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Suny
October 10, 2013 at 8:33 PM delete

Hello Swagatam,
how can I use the scheme to feed 10 pieces 5w cree diodes at 1300ma?

Thanks!

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October 11, 2013 at 10:32 AM delete

Hello Suny, please refer to this article, if you have doubts you can get them clarified under the article:

http://homemadecircuitsandschematics.blogspot.in/2013/05/cree-xlamp-xm-l-led-datasheet-highest.html

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Neelesh
October 12, 2013 at 1:53 PM delete

Hii Swagatam,
Can you suggest me the power supply rating's, if i want to power this led panel directly from the power source. And it would be great if you give me the equivalent circuit for that power supply. Plzz explain me the working of P1 in the circuit.

And you are doing great job for all the hobbyist's and all the circuit's you gave are very useful. Please continue doing this.

Thanks!

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October 12, 2013 at 7:09 PM delete

Hi,
I want to connect multiple 1W LED to my 12V/4.5Ah or 12V/7.5Ah battery then the ckt given will remain same or change???
What is the voltage and current consumption of this ckt??? For how many hours will i get backup??????

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October 12, 2013 at 9:47 PM delete

Thanks Neelesh,

P1 is for varying the intensity of the LED.

You can try the following smps circuit for powering it:

http://homemadecircuitsandschematics.blogspot.in/2013/10/12v-24v-1-amp-mosfet-smps-circuit.html

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October 13, 2013 at 10:20 AM delete

please refer to the following link, you can use this circuit for your application:

http://homemadecircuitsandschematics.blogspot.in/2013/07/making-led-halogen-lamp-for-motorbike.html

current and backup will depend on the number of leds included.

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November 21, 2013 at 9:24 PM delete

sir i need 12w led street light circuit please

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Anonymous
December 2, 2013 at 12:39 PM delete

sir i need to extend this circuit for 60 small LED s. so how can do this

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December 2, 2013 at 8:01 PM delete

You can use the same circuit, no changes would be required

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Anonymous
December 7, 2013 at 4:05 PM delete

can i use this circuit in my car? for eg indoor lamp!

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Anonymous
December 9, 2013 at 5:12 PM delete

thanks, one more question - what is the least number of led's i can use in this circuit i.e. can i use only 3 leds or can i use 6 leds?
regards

mandar

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December 10, 2013 at 12:06 PM delete

divide the supply voltage with 3.3, it will give you the exact number of LEDs (in series) which can be accommodated, ...........ignore the decimal place

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January 20, 2014 at 1:45 AM delete

it is not working in the simulator software....please help

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January 25, 2014 at 1:55 PM delete

dear sir,my circuite and 1w led strip distance is 10m .this is effect to led brightness.please help

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February 18, 2014 at 1:03 PM delete

can i connect this to a 60ampn12v battery ?

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February 18, 2014 at 2:08 PM delete

i want to use this circuit as a normal tube light, with no solar. i want to use only 12v dc. what parts i need to remove?

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February 19, 2014 at 10:15 AM delete

you can use only the LED/resistor bank and connect their respective positive and negative wires to the 12V DC source.

The circuit does not have a current control stage, so make sure the voltage never exceeds it's predetermined mark, and more than adequate heatsinking is provided to the LEDs.

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March 22, 2014 at 11:17 AM delete

Hi Sir,
I want a led driver circuit for 40*1w led with the power supply of 12v car battery.Please do help with it sir.

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March 23, 2014 at 9:02 PM delete

Hi Vinu,
you can use the LED/resistor configuration shown in the first diagram in between the collector of the transistor and the positive.
Use it directly with the battery supply. make sure to use a large heatsink for the LEDs.

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March 24, 2014 at 11:40 AM delete

Hi sir,
I'm a mechanical engineer...interested in electronic works too......i tried the above circuit b4 and after your reply....i felt only the led glows with help of TIP122 not because of the 555 timer.....please do help me with it.....i'm totally collapsed sir.....if not will u help me with 40*1w led( 20*1w led + 20*1w led) separate separate circuits with same full brightness of the led throughout.....

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March 24, 2014 at 9:51 PM delete

Hi Vinu,

the 555 stage is for dimming purpose, you can remove if the feature is not required.
As suggested earlier, you can use the LED/resistor configuration shown in the first diagram in between the collector of the TIP122 and the positive line.
Use it directly with the battery supply. make sure to use a large heatsink for the LEDs.

Use 40 numbers for 40 watt and 20 nos for 20 watt

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April 3, 2014 at 10:31 AM delete

Hi Sir,
I want a circuit such as input 12v /35A from a automobile battery to 12v /1A as output it should be a constant current circuit.

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April 3, 2014 at 7:13 PM delete

Hi Vinu,

you can use the first circuit from this link:

http://homemadecircuitsandschematics.blogspot.in/2013/06/universal-high-watt-led-current-limiter.html

use R1 = 1.25 ohms



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April 4, 2014 at 11:04 PM delete

Hi Sir,
i tried the above circuit using that LM317 still the high power leds didnt get the full brightness...

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April 6, 2014 at 8:32 AM delete

Hi Vinu,

Replace LM317 with LM338 and calculate R1 as per the LED current requirement.

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June 12, 2014 at 11:14 PM delete

Hi sir,
i made this LED light using 3 led in series & 6 line parralel. I check amp & voltage accross connection i used one dumped battery it show 11.79 v & 0.41 amp i calculate watt is(p= V* I) 4.89 watt = 11.79 v * 0.41 amp.
so above calculation shows that it consume only 4.89 watt. But 1 watt led are 18 no. that means it has consume 18 watt power right so ?
any calculation problem?
Can we calculate consumption of battery AH & time for discharge?

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June 13, 2014 at 10:12 AM delete

Hi Ashok,

did you connect resistors in series with each string??

If not then your LEDs might be gone and dead.

If you have included the resistor then it clearly indicates that the battery has no power in it to support the LED.

Instead of the battery you may use a 12V, 2amp SMPS for testing the assembly.

don't forget to include 6 ohms/1watt resistors with each of the 3 LED string.

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June 13, 2014 at 10:15 AM delete

...battery back -up with respect to AH can be calculated only with brand new batteries, for old/used batteris it may be difficult due to their unknown "health" conditions.

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June 13, 2014 at 11:23 AM delete

yes i use 6 ohm 2 watt resistor in series of 3 led as per your design. As you stated battery has no power, battery gives power 11.79 volt & LED also glow but my question is about power consumption only. I share only data collected after LED glow that is Amp & voltage.

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June 13, 2014 at 1:35 PM delete

check with a 12V 2amp ac/dc adapter power supply to confirm the results

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June 14, 2014 at 1:52 PM delete

Mr.Swagatam

thank u for the circuit its working...

bt i have to use this ckt for aquarium and for that i will use only 10 led each to a resistor .... and i worked in that fashion ...the resistor of 2 watt is going very hot after just 5 sec of use so could u tell me which resistor to use ............ or any modification required

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June 15, 2014 at 9:22 AM delete

Hello Chetan,

How did you connect the 10 LEDs, surely they will not work in series with 12V??

and in parallel with 3 in series would produce 9 LEDs total, so I am confused how you might have connected them??

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August 5, 2014 at 4:31 PM delete

In that case, If i am using a 5v dc supply, then is this ckt valid for 1 led(1w)?
thank u in advance...

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August 5, 2014 at 4:42 PM delete

Hello Mr.Swagatam

I have some doubts:
1. can we use this ckt for single 1watt led?(I want to make lights with one 1watt led...can u help with the circuit.)
2. if the ckt is connected as per your design(the whole 39 leds)...what is the total power consumption, in watts?
3. I would like to make a 3W, 5 W, 7W etc..lights....for house hold purposes...can your circuit be helpful?
4. I have an LED which is of size of the big almond(assume round)...I am unaware of how to rate its wattage...can u please help?

thank you....

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August 6, 2014 at 10:29 AM delete

Hello Mr. Krishna, here are the answers:

1) for 1 watt LED use only one 1 watt led at the transistor collector with a 22 ohm 1 watt series
2) the wattage will depend upon the pot position, it could be anywhere between 2 watts to 30 watts
3) please specify the voltage specs of the individual LEDs for the calculations.
4) without checking it practically it would be difficult to specify the ratings of the LED correctly.

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August 6, 2014 at 8:22 PM delete

Hello Mr.Swagatam...

I am very happy for your timely responses....

1. with the issue regarding 3W,5W,7W etc lights....I would like to have the circuit with 220V mains, and also with 6V and 4.5Ah/1Ah DC supply.....I am just doing this to light my house so that I can save wattage consumption and save electricity bills....and here I am having only 1W leds in my house.....so I would like to build those 3,5,7 Watts bulbs....

2. well to give you clarity of that led that I have..I will send you the link which is containing the pic.....the last one in pale yellow color.....

http://www.google.co.in/imgres?imgurl=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F9%2F9e%2FVerschiedene_LEDs.jpg&imgrefurl=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FLight-emitting_diode&h=1193&w=3392&tbnid=gnMMC7_VDec9SM%3A&zoom=1&docid=rpWfim4m9Naq7M&ei=Zj3iU5LrEoWwuASRoYKAAw&tbm=isch&ved=0CC4QMygCMAI&iact=rc&uact=3&dur=2909&page=1&start=0&ndsp=15

and also please if you find time share the links of different LED projects especially in home lighting....

thank you so much.....and waiting for your reply....

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August 7, 2014 at 10:19 AM delete

Thank you Mr. Krishna,

From the image it looks like an ordinary 30mA or a 50mA, 8mm type of LED, it's surely neither a 3watt nor a 5watt LED.

For acquiring higher wattage outputs, you can connect 1 watt LEds in series or in parallel and use it with your 6V battery.

With a 6V supply you can connect two 1 watt LEDs in series and connect it directly across the battery terminals, no resistors would be required. For more power you could probably make another string of two and connect it in parallel to the above...this will give you 4 watts of output.

A 6V/4.5AH will not tolerate beyond this, so please do not exceed above 4 watts.

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August 7, 2014 at 10:21 AM delete

....here are some LEd circuits that could interest you:

http://homemadecircuitsandschematics.blogspot.in/p/led-driver-circuits.html

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August 8, 2014 at 7:31 PM delete

Thank you Swagatham..........
I am really glad for your help..........i will contact you if I had any doubts in mid of the work.......
thank you once again......

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August 24, 2014 at 4:00 PM delete

Swagatam Majumdar sir i am your fan on doing simple with your help comments
i want to know
1 we are playing badminton on my friend lawn for lighting we are using halogen 500 watt
2 which consumes more .can you suggest any idea like making 200w led circuit from
ac power supply
3 making making same or greater luminasence circuit

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August 24, 2014 at 7:47 PM delete

Hi Karthik thanks!

You can try any of the following design as per your preference for making 100 watt LED lights, a couple of these could be made for getting 200 watts:

http://homemadecircuitsandschematics.blogspot.in/2011/12/make-hundred-watt-led-floodlight.html

http://homemadecircuitsandschematics.blogspot.in/2014/07/capacitor-based-led-tubelight-circuit.html

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February 11, 2015 at 12:32 AM delete

Please brother make some high watt a.c LED driver circuit with transformer or without transformer. Such as for 50 watt (32-35v, 1750 mA), 30watt (32-35v, 900mA), 20watt (32-35v, 600mA), 10watt (9-12v, 900mA). Moreover please make those circuit using multiple of the LEDs. Like 3 or 4 numbers of 10 watt LEDs, 2 numbers of 20watt LEDs. Looking forward for your effective replay.

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February 11, 2015 at 11:14 AM delete

Hi Rajib, here's one circuit which you can try for any 32V high watt LED....single or in parallel:

http://homemadecircuitsandschematics.blogspot.in/2014/09/32-v-3-amp-smps-led-driver-circuit.html

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April 1, 2015 at 12:34 PM delete

Respected Sir,
I would like to know the reason behind the selection of R1=100k P1=100k and C1=680pF

my mail id : hansdcruz@gmail.com

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April 1, 2015 at 5:48 PM delete

Hi Hans,

R1 and C1 basically enables to produce a frequency for the LEDs, and P1 becomes responsible for adjusting the duty cycle (ON/OFF time) of this frequency.

Here R1 and C1 ensure sufficiently high frequency so that the LEDs run smoothly without exhibiting any flicker, P1 is selected such that the range of the dimming can be achieved from minimum to maximum or as much as feasible.

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July 21, 2015 at 12:41 PM delete

How to connect this circuit with previous circuit and how to design led street light circuit of 16wtt,18wtt,24watt,36watts.plzz Sir help me.can you provide the circuit diagram for these

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July 21, 2015 at 5:04 PM delete

connect the supply lines of the above circuit with the points indicated as "To LED lamp module" in the previous circuit

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December 26, 2015 at 10:35 AM delete

Sir, can i use 12v led?? Which is readly avilable??? It has limiting resisitor alredy connected in the led board

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December 28, 2015 at 11:39 PM delete

Hi sir swagatam !!!
i am going to make police flasher with 555 and 4017 ic but i want to use one watt leds(R,B)
2 red and 2 Blue...Is it possible with 9v battery ?? is any resistance required ?

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December 29, 2015 at 10:29 AM delete

Hi Asif, a 9V PP3 battery will not work....you'll need a 9V 2AH or bigger AH battery.

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December 29, 2015 at 10:33 AM delete

resistor will be required.

use this formula
R = 9 - total LED voltage in series / 0.3

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January 20, 2016 at 12:01 AM delete

Hi dude I have doubt that if voltage of battery downs to 10 from 12 v means.does there will be change in brightness of led ?

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January 20, 2016 at 8:16 AM delete

Hi dude, yes obviously the LED brightness level will also change from high to low.....

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