An emergency lamp using SMD LEDs is able to generate illuminations with extreme brightness due to the high efficiency of the SMD type LEDs. Moreover, SMD LEDs also ensure the unit will be very compact and lightweight.
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
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
Comments
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.
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.
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 🙂
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.
the leds dont shut down but it dims its light sir.
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.
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.
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.
dhanusu, please provide the wattage of the LEDs so that i can calculate it correctly.
If I Give 12v supply through transformer 15v zener is needed in circuit or shall I remove zener. Pls tel.
you can remove the zener.
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
use a 7805 IC in between 4V batt and 12V batt.
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
Hello Sameer,
you can try this circuit:
https://www.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.
yes…
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.
sir i want to know that why u used a R2 in parallel how supply voltage offs and blink led on battery through R2
it transistor can change with another model?