The following post explains a simple circuit diagram of an automatic emergency lamp using 36 nos. SMD LEDs. The circuit has been presented in response to the following request sent by Mr.Ali Adnan.
Circuit Request for SMD Emergency Lamp
"Hi,How r u Bro?? I Hope you are enjoying Good and Healthy life. Bro I've 36 SMD LEDs(Side View Type), I Extracted them from my Broken Laptop's LED LCD screen. I tested them with multimeter and found all LEDs in working condition.
Now I want to make some useful from them like an emergency LED lite. I'll remove all 36 LEDs from strip and mount them on a PCB (will be Tough JoB Mounting SMD's) once you will design a circuit for me to drive them.
I don't know much about SMD LEDs so that's why I am bothering you. I googled for data sheet for that type of LEDs and I think I found right data sheet for this LED, please also compare the pictures of LEDs and data sheet.
I am attaching actual pictures of LEDs that I have and also attaching data sheet, please check and help me with a simple circuit with simple parts. and just for information I've not found the IC ZXSC310 (that you used in your 1 watt LED circuit) here in Lahore Pakistan 🙁 and I am too sad for this.
Waiting for your Reply.
Best Regards,
Ali Adnan Khan"
"Hi Bro,
What kind of emergency light do you want to make? Automatic AC/Dc operated or just direct on battery?
The datasheet and the pics are OK.
Best Regards,
Swagatam"
"Hi, thanks for your reply bro. Automatic AC/DC operated with battery backup."
OK, here's an automatic ac/dc emergency light circuit using the proposed 36 SMD LED lights which is easy to build, cheap and yet reliable.
CAUTION - THE CIRCUIT IS NOT ISOLATED FROM AC MAINS, UTMOST CARE MUST BE OBSERVED WHILE TESTING THIS CIRCUIT IN UNCOVERED POSITION.
ALTERNATIVELY YOU MAY INCORPORATE A 12V, 500MA DC ADAPTER ACROSS THE ZENER DIODE INSTEAD OF THE SHOWN TRANSFORMERLESS POWER SUPPLY FOR AVOIDING THE ABOVE CAUTION.
The Design of a an Automatic SMD based emergency lamp is shown below, as per the above request specification:
Parts List
All resistors are 1/4 watt, 5%,
R1 = 1M
R2 = 1K,
R3---R14 = 56 Ohms
C1 = 2uF/400V PP Capacitor
C2 = 100uF/ 25V
D1, D2 = 1N4007,
D3, D4 = 1N5402
T1 = TIP127
Z1 = 15V 1 watt zener diode
Battery = 12V/2AH
LEDs = SMD, 3V white, 20 mA
DYNAVISION says
Automatic ac led lamp to operate when ac fail and it will go to dc battery circuit digram
siddharth sharad srivastava says
hello sir,
sir i want to use two 6v 1aH BATTERIES in series with the circuit,so what modification would be required.
Swagatam says
Hi Siddarth, you can use the same circuit as given, no modifications would be required,
siddharth sharad srivastava says
sir the batteries i am using are 6V1aH li-on battery, Will that suffice ??? also the led smd i have with me has 84 units in it so any modification would be required???
Also i want to add a feature of IR control, so what should i do??
Swagatam says
Siddharth, 6V 1ah is OK for the circuit, but it won't support 84 LEDs, it would get discharged very quickly.
for IR control you can try the following method
https://homemade-circuits.com/2012/02/how-to-make-simple-infra-red-remote.html
siddharth sharad srivastava says
sir,
i want to use two 6v 1AH batteries in series. So what modifications would be required.
Siddh says
Hii.i want 220ac to 22volts dc 2.5amps circuite with out transformer.
karthik kanna says
sir how much time does take for full charge??
Swagatam says
70mA 12V
Arun Kumar says
This circuit how many output voltage & amps
Arun Kumar says
I used 12v realy this circuit out voltage & amps please tell me sir
Swagatam says
use a 12V relay with 300 ohm or 400 ohm coil resistance
Arun Kumar says
I used ac supply working time LED OFF MODE I used relay what volt realy used sir please tell me sir
Swagatam says
relay coil voltage should match the zener voltage….
Arun Kumar says
Iam add in 12v 2 amps Battery Two Battery parller
Swagatam says
ok will do.
Arun Kumar says
I want one 12v 4.5amps battery any modifications circuit diagram please tell me sir
Swagatam says
no modifications would be required
Arun Kumar says
Thanks you sir
Arun Kumar says
How to converted battery zener series
Or parller connect please tell me sir
Swagatam says
connect the black line of the zener with the battery (+) terminal and the other side of the zener with the battery (-) side…use a 14V 1 watt zener
Arun Kumar says
How to Stop over charging this circuit
Swagatam says
connect a 14V/1watt zener diode right across the battery terminals, this will do the job for you.
Arun Kumar says
I used 12v 4.5amps this circuit
Arun Kumar says
I used 6v 4.5 amps this circuit diagram
Swagatam says
you can use the second circuit from the following article:
https://homemade-circuits.com/2014/06/flashing-led-battery-status-indicator.html
use only a single 5mm red LED with the last transistor
Arun Kumar says
How to fixed charging indicate led ?
I used 2 12v 2 amps battery parallel how to modify circuit?
This circuit support 6v 4.5 amps battery used?
Swagatam says
Connect a resistor in series with D2, and connect an LED parallel to this resistor, as long as the battery charges this LED will glow and will gradually shut-off as the battery reaches full charge.
the resistor value could be anywhere between 2 and 10 ohm….you will need to experiment the right value
if possible connect a 47 ohm resistor in series with one of the LED lead for safeguarding it
Arun Kumar says
How to fixed charging LED please send me sir
Swagatam says
I did not understand?
Arun Kumar says
How converted in to 12v /7AH battery used this circuit please tell me sir
Swagatam says
this circuit cannot be used for charging a 12V/7AH battery.
karthik kanna says
I am having transformer 12v 2Amps. i replaced it, the whole night it took, but Battery backup didnt increase.. The system works (when the AC is on, DC off). the transformer is also so Hot….
Swagatam says
your battery could be internally damaged….put an ammeter in series with the battery and check how much current it is taking in…if it shows zero will indicate a faulty battery.
karthik kanna says
the circuit works well but it charges slowly in my 12v 5amps bike battery. how to charge fast pls help me
Swagatam says
for quicker charging you will need to remove the transformerless supply stage consisting C1, R1, Z1, and replace it with a 12V 1amp AC/DC adapter input
karthik kanna says
i am having 12v 5amp Bike battery, it has 8.5v. it charges slowly… how to recharge fast
Please help me
jithin says
Sir
Your circuit ideas are valuable and useful.So many people are taking advantage of it
You are rendering a great service to the world.
Best regards
Best regards
Swagatam says
thank you Jithin!!
Syed Arham says
Sir can you provide me any schematic or give any idea about the 2 watt led blinker with strobe light.(i will use two 1 watt led in parallel)..
The circuit should work in this manner…When we press the button the led will glow continuously and the second press will make the led to Blink. and finally the third press will turn off the led.
I have seen similar feature in Cree led torch ..
Sir please guide me…
Swagatam says
Syed you can try the circuit that's shown in the following link with a few external modifications:
https://homemade-circuits.com/2013/08/single-push-10-step-selector-switch.html
Remove all the relays and connect the LEDs at the collector of the pin2 and pin4 transistors, use TIP122 for the transistors.
Connect pin7 with pin15 through a 10k resistor instead of pin10 and remove the transistor stage at pin7 because we don't need it.
Now make a 555 PWM circuit and integrate its pin3 VIA a DIODE 1N4007 to the base of pin4 transistor…diode anode to base, cathode to pin3 of 555.
That's it your circuit is ready.
Kimberly Grumo says
we haven't use a bridge rectifier sir. may i know what diodes to use? thanks a lot sir.
Swagatam says
Kim, you can use 1N4007 diode for making the bridge or simply connect the transformer wires directly across the anode of D1 and ground in the circuit that's shown in the above article.
remove C1, R1,Z1 these are not required.
Kimberly Grumo says
thanks for the help sir. we will try changing it and tell you the results.
Kimberly Grumo says
thank you very much sir.
its like the AC is giving it power because you can notice the light flickering. im sorry sir but im new to transistors but I know that it can act as a switch.
I can see that you changed the position of D3. we haven't tried that yet.
I also measured the voltage across the base and emitter. when the AC is off, it has voltage and when it is on, the voltage is zero. but I connected it to D3 in the old diagram where it is directed to the LEDs. Is it wrong?
Swagatam says
thanks Kim,
yes I have made a slight change by putting D3 at the emitter of the transistor, just to make the results more accurate.
By the way did you use a bridge rectifier for rectifying the transformer voltage to DC before applying to the circuit?? otherwise the LEDs won't shut off correctly.
You can try changing the position of D3 as shown in the new diagram and check the results.
Kimberly Grumo says
we are using an 18 volt transformer with 750ma
we love your work a lot and we think that it is amazing. but sir we are having a problem now. thank you very much for your help.
Swagatam says
with 18V at the base of the transistor it should completely cut of….
the transistor may not be OK, or some other issue could be there.
Kimberly Grumo says
Good day sir,
May I ask if it is okey to put an 18V/750mA transformer instead of a transformer-less AC supply? and change D3-D4 to 1N4001 or 1N5401?
Also, whenever I connect the AC supply, the LED are still giving light. What could be the possible problem?
Your kind response wuold be greatly apprecieted. Thanks.
Swagatam says
Good day Kim,
yes a transformer power supply could also be used
use 1N4007 for D1,D2, 1N5401 for D3/D4.
if LEds are not shutting off at mains switch ON, indicates a faulty transistor or incorrectly connected transistor.
Kimberly Grumo says
yes sir. we are already using those diodes on our circuit. On a tip127 transistor, is the base on the left most pin, collector on the middle pin and lastly emitter on the last pin?
and we are using two 6volt batteries in series with 4aH each. whenever we connect the AC source, the led's just dims.
and lastly, we are using a ready made led sheets with 3 SMD leds per sheet that is intended for cars. does these have to do with our problem?
please sir, you've been a great help. thank you very much.
Kimberly Grumo says
the leds dont shut down but it dims its light sir.
Swagatam says
Kim, increase the value of R2 to 10K, or 22K, or 33k until the LED shuts off completely while mains is present.
please remember that the base voltage (or the supply voltage from the transformer) to the transistor must be slightly higher than the battery voltage otherwise the LEDs will keep glowing even if R2 is increased to any level.
Kimberly Grumo says
we already tried to increase to R2 to 10K but the transistor heats up and the leds wont light. the leds only light up when we use 1k resistor on R2.
is it okey to remove the transformer?
thank you very much sir 🙂
Swagatam says
measure the voltage across the base and emitter of the transistor with transformer supply ON, and also everything else connected.
It should be around 0V to make the leds shutof.
if not, check and make sure the rectified voltage from the transformer is higher than the battery voltage….
if still it doesn't work, your transistor could be faulty.
or you can opt for a NPN transistor design circuit as shown at the extreme end of this article:
https://homemade-circuits.com/2011/12/how-to-make-efficient-led-emergency.html
Dhanusu AR says
Sir iam using 12v 5amp bike battery with 40leds. Brightness is low. If I directly connect leds to battery brightness is good. I used 6.8ohms resistors R3-14. Please tel how can I modify circuit to get more brightness. Thanks.
Swagatam says
dhanusu, please provide the wattage of the LEDs so that i can calculate it correctly.
Dhanusu AR says
If I Give 12v supply through transformer 15v zener is needed in circuit or shall I remove zener. Pls tel.
Swagatam says
you can remove the zener.
Raja Banerjee says
need a ckt to drive Chinese led torch (4 led in parallel with only one limiting resistor to the bank, operate on 4 v rechargeable battery) from a 12 v bike battery without any power loss. thanks
Swagatam says
use a 7805 IC in between 4V batt and 12V batt.
Sameer Ali says
hello dear sir,
i want to make an automatic AC/DC led light switch with transformer less supply.
when AC supply on the led,s should be on and when AC fails then it should be shift to battery back up .
i want to run only 5 LED,s of 1 watt each.
i shall be very thankfull to you for this.
best regards.
Sameer Ali
Swagatam says
Hello Sameer,
you can try this circuit:
https://homemade-circuits.com/2011/12/how-to-make-efficient-led-emergency.html
use TIP127 instead of the shown transistor.
you will need a transformer power supply for driving 5 watt leds as shown in the first figure.
Anonymous says
can i use 1 x 1 watt led?
Swagatam says
yes…
Anonymous says
hai sir i have a 6v 4.5ah battery.what are the modification required in this circuit and how many led's can use
Swagatam says
You can try the following circuit….you may remove the three collector diodes, they won't be required:
4.bp.blogspot.com/-ZCs8Ry6l_nE/T12Li7DXPDI/AAAAAAAAA64/8JHMz9lAeUw/s1600/led%20emergency%20light%20circuit%20diagram.png
The LED resistors may be selected as 100 ohms.
aimal daud khan says
sir i want to know that why u used a R2 in parallel how supply voltage offs and blink led on battery through R2
stemsa89 says
it transistor can change with another model?
pp says
Hello…Instead of 36 LEDs..How many of 1 Wtt LEDs will require in this particular schematic??
Regards,
Swagatam says
Hello PP,
The above circuit won't support 1 watt LEDs.
august10 says
sir, can i use 5mm led instead of smd?
Swagatam says
yes
Anonymous says
dear sir,
i want to use 100 led with your circuit. is it possible or what i have to change.
thanks
Swagatam says
use 12v/7ah battery
Anonymous says
how could i improve the output ampere
Swagatam says
make this:
https://homemade-circuits.com/2013/02/make-this-automatic-10-watt-to-1000.html
Ramalingam K says
Can we give 12V, 500 mA connection in the place AC input or should we need to give only 230v AC?
Swagatam says
you can replace the given capacitive power supply with a 12V/500ma AC/DC adapter input, it will work.
Ranjit Sur says
I have learned lots of circuits from your blog.
I want to use a 4v 0.5 amp battery.
How many LED can I use and what modifications are needed to this circuit.
Swagatam says
it will allow only single leds in each chain, may be four in parallel, resistors won't be required with the leds.
Ranjit Sur says
should I use a 3 volt or 4.7 v Zenor or 12v as it is?
for a 4v 1 amp battery 24 led can I use?
can I use a n5408 diode instead of 2 1N5402?
I am not able to find 5402 in my area.
Swagatam says
use a 6v zener diode.
24 leds will not work, you may use around 5 to 6 of them (5mm type).
don't use any diodes, simply connect the transistor collector directly with the LED chain
marc says
Good day Sir..
what other values of capacitor that i can use to replace 2uF/400V PP Capacitor because it's not available in our market
Swagatam says
use two nos. 105/400V in parallel, that will become equal to 2uF.
Tazz says
i m talking about to increase the voltage and current which we have to supply the battery what changes should i do please tell me thanks in advance.for eg i ve to charge 16 volt 5 amp battery.
Swagatam says
Increase the value of the zener diode to 20V, and make C1 = 2uF/400V
Tazz says
i ve tried this circuit and its working fine.how can i increase the current and voltages using the same circuit.
Swagatam says
You can do it by upgrading the battery, and the input capacitor accordingly.
mefan says
hi and thanks for circuit
please let me know
is this circuit can stop charging after battery is full and stop battery over load charging or not?
Thnx again
Swagatam says
Hi,
No this circuit will not disconnect the battery when it's fully charged.
mefan says
how can i add this function to this circuit?
Swagatam says
add a 13V zener across the battery points, it will prevent the battery from getting overcharged.
mefan says
thank you very much bro
I'll test it
and report you the result
Museums Information says
Sir, I have changed the R2 to 15K, now the problem was solved. But brightness seems to be low, how can i increase the brightness of led's without changing the battery or decreasing the led's. If I change R3-R14 resistors to 10E, LED'S will bright higher. Please tell sir.
Swagatam says
I have answered it above….
Anonymous says
Dear sir If 12v battery removed from the circuit can i get out put 12v from there? how much amphere can i get from there? i mean as a transformerless power supply? jayanathranasinghe3@gmail.com
Swagatam says
you will not get 12V from the transistor collector if the battery is removed….if you are looking for a transformerless power supply then you may try this circuit, max amp will be around 70mA.
https://homemade-circuits.com/2011/12/cheap-yet-useful-transformerless-power.html
Museums Information says
Sir,
I have two doubts: 1.Can i use 12v 5a.h amco bike battery.
2.If AC is on leds will turn off or not.
Swagatam says
Yes it can be used, with input AC the LEDs will be OFF…..
Museums Information says
Sir, Circuit working fine. But R2 transistor is getting heated when AC power off and led off mode. Also battery is getting drained thru this R2 resistor. Charged supply is getting drained. In AC off mode LED's is lighting brightly only for 20 mins. Please guide sir. How to increase the back up and how to prevent battery get drained in AC off mode. I am using 12v 2.5AH AMCO bike battery and 12v transformer of 1 amp to charge the battery.
Swagatam says
Increase the value of R2 to 10K or more and see what happens, this should solve both the problems.
Museums Information says
Thanks sir, I changed R2 to 15k. Now my problem solved. How can i increase the brightness of led's without changing battery voltage and number of led's count. If I reduce R3-R14 to 10E, will increases brightness??. Please tel sir.
Swagatam says
yes reducing R3-R14 will increase LED brightness, but the value will depend on the type of LED used, if it's not calculated correctly might damage the LEDs.
Deepak says
Hi,
nice one, In this project i required one modification.My hobby is to create such circuits and i like it to do but no detailed information about circuits designing so i am requesting you for circuit diagram for this modification.
In this emergency light i Want to charge battery with the solar panel also with a one switch button, that means when i switch to AC supply then battery charge with AC supply (which normally requires in rainy season) and if Switch to Solar panel then battery should charge with solar energy. I have solar panel of 12V 320mA.(if we can increase mA so that required current will maintain.)
Thanks in advance.
Swagatam says
You can do it with the help of a DPDT switch which has three terminals. The center terminal will go to the battery positive, out of the other two terminals one will go to the solar panel positive and the other will go to the ac/dc adapter positive. All the negatives of the three systems should be joined together which will form the negative line.
Deepak says
yes yes, DPD switch can use here. But i need something to enhance energy getting from solar panel 12v 320mA, is it enough to charge 12V 7.2AH battery?
Once i tried also but current is flows in back direction towards solar panel immediately i removed the connections. so any circuit for enhancing solar power.
Thanks.
Swagatam says
The voltage and current from the solar panel will depend on the sun ray intensity, it cannot enhanced artificially. You may have to use a bigger solar panel, or connect two in parallel.
Use a 1N5402 diode in between the solar panel positive and the battery positive, this will stop reverse current flow from battery to panel.
Dhananjay Ganvir says
hi there…
Can i use only 30 leds instead of 38 ?
thanks
Swagatam says
Yes, you may do it.
Dhanushka Agalakada says
Dear Sir,
This is a very nice project. And please let me know, is the battery is charging during the mains supply present??
Thanks
Swagatam says
Dear Dhanushka,
Yes the battery is charged when mains ac is available.
ali says
Thank you so much bro, you are gr8. May GOD give you and your family healty and happy life.
Best regards.
Ali
Swagatam says
Thanks Bro,
Wish you all the same.