40 Watt LED Emergency Tubelight Circuit Using 1 Watt 350 mA LEDs

The article explains a simple yet effective 40 watt LED emergency tube light circuit which can be installed at home for acquiring  uninterruptible illumination at the same time saving a lot of electricity and money.


You might have reads one of my earlier articles which explained a 40 watt LED street light system. The power saving concept is pretty much the same, through a PWM circuit, however the alignment of the LEDs has been laid in a completely different manner here.

As the name suggest the present idea is of an LED tube light and therefore the LEds have been configured in a straight horizontal pattern for better and efficient light distribution.

The circuit also features an optional emergency battery back up system which may be employed for getting an uninterruptible illumination from the LEDs even during the absence of normal mains AC. Due to the PWM  circuit the acquired backup can extend up to more than 25 hours on every single recharge of the battery (rated at 12V/25AH).

The PCB would be strictly needed for assembling the LEDs. The PCB must be an aluminum-back type. The track layout is shown in the below given picture. As can be seen the LEDs are spaced at a distance of about 2.5 cm or 25mm from each other for enhancing maximum and optimal distribution of light.

Either the LEDs may be laid over a single row or over a couple of rows.

A single row pattern is shown in the below given layout, due to lack of space only two series/parallel connection has been accommodated,  the pattern is continued further on the right side of the PCB so that all the 40 LEDs become included.



Normally the proposed 40 watt LED tube light circuit, or in other words the PWM circuit may be powered through any standard 12V/3amp SMPS unit for the sake of compactness and decent looks.

After assembling the above board, the output wires should be connected to the below shown PWM circuit, across the transistor collector and positive. The supply voltage should be provided from any standard SMPS adapter as mentioned in the above section of the article. The LED trip will instantly light up illuminating the premise with flood light brightness. The illumination may be assumed to be equivalent to a 40 watt FTL with power consumption of less than 12 watts, that's a lot of power saved.


Emergency Battery Operation

If an emergency backup is preferred for the above circuit, it may be simply done by adding the following circuit.

Let's try to understand the design in more details:



The circuit shown above is the PWM controlled 40 watt LED lamp circuit, the circuit has been elaborately explained in this article. You can refer it for knowing more about its circuit functioning.

The next figure shown below is an automatic under voltage and over voltage battery charger circuit with automatic relay changeovers. The whole functioning may be understood with the following points:

The IC 741 has been configured as a low/high battery voltage sensor and it activates the adjoining relay connected to the transistor BC547 appropriately.

Assume the mains to be present and the battery to be partially discharged. The voltage from the AC/DC SMPS reaches the battery through the N/C contacts of the upper relay which remains in an deactivated position because of the battery voltage which may be below the full charge threshold level, let's assume the full charge level to be 14.3V (set by the 10K preset).

Since the lower relay coil is connected to the SMPS voltage, stays activated such that the SMPS supply reaches the PWM 40 watt LED driver via the N/O contacts of the lower relay.

Thus the LEDs remains switched ON by using the DC from the mains operated SMPS adapter, also the battery continues to get charged as explained above.

Once the battery gets fully charged, the output of the IC741 goes high, activating the relay driver stage, the upper relay switches and instantly connects the battery with the N/C of the lower relay, positioning the battery in the standby condition.

However until AC mains is present, the lower relay is unable to deactivate and therefore the above voltage from the charged battery is not able to reach the LED board.

Now if suppose AC mains fails, the lower relay contact shifts to the N/C point, instantly connects the supply from the battery to the PWM LED circuit, illuminating the 40 watt LEDs brightly.

The LEDs consume battery power until either the battery falls below the low voltage threshold or mains power is restored.

The low battery threshold setting is done by adjusting the feedback preset 100K across the pin3 and pin6 of the IC741.

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40 comments

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Anonymous
November 27, 2012 at 5:18 PM delete

Hi, it is a good one, can we have the 12V smps circuit for this.

Housing this LED and protecting it from eyes is the catch here. is there a design detail about putting this unit in a housing. may be a Acrl glass sheet be used.

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November 27, 2012 at 8:13 PM delete

Thanks!

A readymade SMPS unit can be used here for simplicity, because the tube light part is itself quite lengthy and complex, we do not want to make the unit anymore complex.

Any standard readymade enclosure can be incorporated or simply the entire LEd strip may be directed toward the ceiling which will produce a reflected light from the roof, safeguarding the eyes of the residents.

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Anonymous
November 28, 2012 at 1:49 PM delete

OK, Sir, thank you, i shall make an enclosure and test it, if found to be good , shall share the same in this blog

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Anonymous
November 28, 2012 at 2:24 PM delete

do u have any circuit about measuring inrush current for lighting eq. ?

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November 28, 2012 at 5:24 PM delete

If you could explain your requirement a little more elaborately then probably I would be able to design it for you.

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Anonymous
November 29, 2012 at 4:36 PM delete

how much max wattage solar panel and max ampire battery can i use with circuit
and can u please modify and update this circuit with 10 amp battery and 100 watt max solar panel support http://ludens.cl/Electron/solarreg/solarreg.gif

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November 29, 2012 at 6:22 PM delete

The above circuit is not intended for solar panel, however if you incorporate a solar charge controller then you can feed the voltage to the SMPS points. Solar panel can be anything from 60 to 200 watts and the battery can be upto 50 AH.

The link diagram specifies a solar panel of 7Amp, which can never charge a 100 to 300 AH battery........in fact it's suitable for a 10 AH battery, just make the shunt transistor collector resistor to 2 Ohms each

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December 1, 2012 at 7:49 AM delete

Hi Swagatam,
Thanks for your prompt response to design a circuit which is inline to my requirements. Again I do have some queries.
1. Here you have mentioned to use 12v/25Ah batteries and they will last for 25 hours on a single charge. It is okay for me to have this setup give me 6-8 hours backup. Kindly help me in modifying the circuit where ever necessary.

2. Secondly, I plan to have this circuit built on 230v straight bypassing the battery part thereby using the above circuit for replacing the tube light with the PWM circuit as you have mentioned of the low power consumption.

Regards
Nagaraj

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December 1, 2012 at 8:02 PM delete

Hi Nagaraj,

As mentioned in the article, if the emergency part is not required the circuit may be powered directly through an AC/DC power supply 12V/3 amps, it may be an SMPS or a transformer type PS.

For backups you can use any 12 battery, the backup time will depend on the AH of the battery.

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Anonymous
December 8, 2012 at 5:31 PM delete

Hello, the second circuit dosent can u please help me, i cant calibrate it , i tried it withe a variable power supply when the voltage drops below 4.5 volts the relay shuts down and i dont know how to set the 10k presaet (charging) please help to calibrate it

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December 8, 2012 at 6:18 PM delete

10 preset is for high voltage cut off and the 100K preset is for the low voltage activation.

Apply 14.2 volts and adjust 10K preset so that the relay just activates.

Then reduce the voltage to 11.5 and adjust 100K preset such that the relay activates back.

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December 20, 2012 at 12:09 AM delete

Hi swagatam,

Can u tell me what will be power consumption of a circuit with serial connected leds.. (two leds are connected in serial, and a total of 10 strings)



Led type : white 8mm wide angle led (straw hat type)
Leds Forward voltage: 3.4
Current: 100 ma
No of serial strings : 10 (each Serial string is connected parallel to the power supply )

No of leds per string : 2

Total no of leds : 20
so.. how to calculate power consumption of this circuit.. !

How many watts ?





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December 20, 2012 at 9:18 AM delete

Hi Bibin,

Each string will consume current depending upon the series resistor value.

so please tell me what resistor you have connected with each series.

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December 20, 2012 at 9:55 PM delete

hi swagatam,

The power supply was 6v 5ah battery.. so i didnt connect any series resistor.. !

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December 20, 2012 at 10:00 PM delete

swagatam... led current is 30ma not 100ma .. sorry... !

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December 21, 2012 at 9:34 AM delete

Hi Bibin,

Please check the formula given in the following article, you may use it for finding current, resistance value and power consumption for any LED series.

http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-wire-led-lights-easy-clues.html

Regards.

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Anonymous
December 31, 2012 at 12:49 PM delete

Hai swagatam,

Thanx for ur great circuit.can I use 6v 4.5ah battery.if yes what are the modifications.

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December 31, 2012 at 2:59 PM delete

Hi Thanks very much!

6V will work but you would have to reduce the LED to one on each series, rest everything can be kept as it is. The series resistors now becomes around 7 Ohms

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Anonymous
January 1, 2013 at 10:45 AM delete

Thank u very much sir

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Anonymous
January 13, 2013 at 1:55 PM delete

Hi Sir Swagatam
can i use this into my motorcycle as an additional lighting accessories? Is there any changes in the circuit component? Thanks in advance sir.

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January 13, 2013 at 8:16 PM delete

Yes, surely it can be used....no changes would be required.

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January 21, 2013 at 5:57 PM delete

Swagatam
could u provided a 220v somewhere 60 to 90 led (3.5v) circuit diagram which look like a tube light type

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January 22, 2013 at 11:07 AM delete

You can try this circuit, connect all the 60---90 LEDs in series:

http://homemadecircuitsandschematics.blogspot.in/2012/04/how-to-make-led-bulb-circuit.html

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January 30, 2013 at 9:02 PM delete

Dear Swagatam,

In the PCB layout for the LEDs given above, I think there is a mistake. The power supply from the PWM circuit directly connects to the first LED and in turn the rest two LEDs are connected in series with the first one with the resistor in between. But in the circuit diagram, the supply is fed to the LEDs via the resistor. kindly clear my doubt.

Regards
Nagaraj

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January 31, 2013 at 9:21 AM delete

Dear Nagaraj,

Both the diagrams are correct, the resistor can be put anywhere in the line of the series.

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Anonymous
June 21, 2013 at 3:13 AM delete

Dear Swagatam,

I want to use 9 to 12 1 watt LED's and 4volts 1.2 AH batteries with a quantity of 3 Nos.
Please advice a circuit with uninterruptible illumination of LED Light in the presence and Absence of AC 220 V input supply.Also please let me know the DC powersupply output voltage to drive the LED's
what circuit will you advice me.
Thanks in Advance
Please reply me at (sohatechnologies@gmail.com)
Regards/Faisal Mateen

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June 21, 2013 at 12:13 PM delete

Dear Faisal,

A 1.2AH batt will support only 1 to 2nos 1 watt leds, so your idea won't be feasible.

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Anonymous
June 21, 2013 at 3:31 PM delete

Please advice a circuit with uninterruptible illumination of LED Light in the presence and Absence of AC 220 V input.
i can use 3 Batteries of 1.2 AH in series so i will get 12 VDC.
Actually these betteries are very low cost here so i want to use it.
And i only need a backup of 2 to 3 Hours .

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June 22, 2013 at 10:35 AM delete

you can try this circuit:

http://1.bp.blogspot.com/-I2zlapFq6RM/UML_NxUJy2I/AAAAAAAAB3w/27ZLDjK9C9g/s1600/simple%20modem%20UPS%20circuit.png

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September 18, 2013 at 1:56 PM delete

Dear Swagtam sir,
Can you tell me that by using 1 watt power led can i make led tube light of 20 to 25 leds which will work on ac supply. plz tell me required ckt.

yogesh

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September 18, 2013 at 7:00 PM delete

Hi Yogesh,

Yes you can do it but you will have to use a AC/DC converter power supply for driving them, direct AC supply will blow them of.

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Anonymous
December 11, 2013 at 9:38 PM delete

Pardon my being a novice who has been so much interested in electronics but has no way of having been into it. Please am so sorry to bother you with the following questions. I want to build the device urgently. So i will appreciate if you could kindly answer the questions all the questions for me.
Please could you kindly tell me what is SMPS unit/adapter?
What is PCB?
How many are the LEDs and how do i split the LED into 2 or 3 sections each?

In the second diagram, under Emergency Battery Operation: where would the 12volts negative and positive be connected?

Lastly, for the automatic under voltage and over voltage battery charger circuit , please what does the connection to the 12VDC from SMPS means. And the connection to PWM circuit? Wont the charger be connected to electric mains (220)

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December 12, 2013 at 11:40 AM delete

Here are the answers to your questions:

SMPS units are power supply units readily available in the market and are used for converting mains 220V or 120V domestic AC to the desired DC voltage such as 3V, 6V, 9V, 12V etc as per the specifications.

For our circuit we require a 12V smps.

These are also rated with according to their current limit specs...in our case we require a 2 to 3 amp smps (12V)

In the first diagram 3nos LEDs are connected in series with an individual resistor, for getting around 40 watt fluorescent equivalent illumination we need at least 10 to 12nos of such strings connected in parallel as shown in the the first diagram.

In the second diagram the smps positive input is connected to the relay N/C contact of the relay and the negative is connected to the line which joins with pin#4 of the IC 741.

As explained above the smps 12v DC output which is derived from the AC mains is connected across the indicated "SMPS input" points in the diagram.

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January 22, 2014 at 10:00 PM delete

Swagatam
i made this Low/ high voltage circuit i used for solar panel charger controller input with 12 volt 7.2 ah battery . still i dont tested because i have some question from schematic diagram because i want some changes like;
1: when input power from solar panel charger is active then load cut and charge continues
2: Input fails to charge then load contunies till discharge point.
my question is that ,
1: When led glow?
2:How to preset set for low discharge point.
mail me: ashokdhenge06@gmail.com

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January 23, 2014 at 7:10 PM delete

Please refer to the following post:

http://homemadecircuitsandschematics.blogspot.in/2013/02/make-this-automatic-10-watt-to-1000.html

Remove the transformer power supply and replace it with solar panel input

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October 29, 2014 at 7:04 PM delete

Sir,
What do you mean by aluminium back PCB .is it available in market.. I have knowledge of hard board or acrylic back PCB.
Why using PWM circuit. Wat is led rating.. Can I use SMD LEDs.

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October 30, 2014 at 9:30 AM delete

It's a PCB with an embedded aluminum base which acts like a heatsink for the soldered LEDs, it could be available readymade in the market as per individual preferences.

The PWM circuit is only for dimming purpose, may be eliminated if the dimming feature is not required.

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Anonymous
May 10, 2015 at 1:03 PM delete

Hi.. I really appreciate your efforts and commitment through this blog. I would like to include a battery backup either with nicd or 4v lead acid batteries in multiple counts to support a recently bought led tube light of 18w. I would like this to be concealed within the t5 fixture. Pls suggest a circuit design that auto charges and backs up lighting when power fails with no or minimal wiring change at home.

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May 10, 2015 at 8:30 PM delete

Hi, thanks!

I think the circuit shown in the following link will suit your application:

http://www.homemade-circuits.com/2013/02/make-this-automatic-10-watt-to-1000.html

the transformer power supply can be replaced with any standard 12V adapter followed by a 7805 IC for supplying the battery under charge.

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