8/14/2019 Night LED Light Circuit Schematic

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Night LED Light Circuit Schematic

Here, a 12VDC /70mA (max) capacitive transformerless power suppl is use! to power t"ree #mm

w"ite straw$"at %&Ds' ne a!vantae of t"is circuit is t"at t"e output voltae will not clim* to an

unsafe level if t"e output loa! is a*sente! * a fault in t"e w"ite %&D strin' +"is safet mec"anism

is realie! * a!!in two ener !io!es (-D1 . -D2) as an interal part of t"e *ri!e rectifier unit'

n an ort"o!ox capacitive transformerless power suppl *ase! %&D circuit, t"ere is a ris of filter

capacitor explosion in an open$loa! con!ition'

+"e circuit is strai"t forwar! an! self$explanator' esistor 1 limits inrus" current' +"e value of

1 is c"osen so t"at it !oes not !issipate too muc" power, et is lare enou" to limit inrus"

current' ee!less to sa, C1 is t"e important component' +"e maximum current flowin t"rou" t"e

circuit components is controlle! 3 almost exclusivel 3 * t"e value of C1' &lectroltic capacitor C2

simpl stores current for release to t"e loa!, an! is rate! at twice t"e voltae expecte! at output'

esistor 4 limits t"e operatin current of t"e w"ite %&D strin, comprisin t"ree w"ite %&Ds (%&D 1

3 4) in series' +"is circuit is suita*le for staircase, corri!or, war!ro*e, *e!room an! *at"room

li"tin applications'

Notes

• An electrocution "aar! exists !urin experimentation wit" t"is circuit' An isolation

transformer (151) s"oul! *e use! w"en pro*in t"e circuit

• f t"e output loa! is increase!, t"e *e"avior of t"e circuit c"anes in unexpecte! was' 6o

*e careful w"ile main our own mo!ifications (not recommen!e!) at t"e output loa!

(w"ite %&Ds)

8/14/2019 Night LED Light Circuit Schematic

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• 6ince t"e circuit is !irectl connecte! to t"e mains networ, ou naturall "ave to ive

a!euate rear! to safet w"en fittin it into a fixture' t is *etter to use a oo! ualit

water$proof plastic ca*inet for enclosin t"e finis"e! circuit

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Disclaimer: All the content of project has been submitted by the author, so if you getany inconvenience by making this project, The Newircuits team will not beresponsible! "t means the submitted project is #as is#! Also "f you have any $uestionabout the project, you should contact the author by email! 

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This is a new circuit I just finished. I like the white LED lighting, it

is softer and give a better view without being overly bright for the

eyes when you just wake up in the middle of the night. This circuit

has no transformer to isolate it, so it is a must to have a proper

enclosure. The lights come on when the photocell is in the dark. Ifyou are using this in a transparent casing, make sure you wrap a

 black electric tape or a piece of tubing to prevent the LED from

triggering off the photocell.

ery important! "se the proper wattage #$ee $chematic% for the

resistors. The circuit was calculated to have the ma&imum LED

 brightness with minimum heat from the '() resistor. *ith a

+'()ohm (*+ flame proof resistor. It will be slightly warm to the

touch.

-rojects photos! /s you can see, I used a standard 0 prong

 plug that usually goes on the end of a cable. I separated the plug

from the hood and also removed the ground prong #not used and

only makes it harder to insert or remove from the wall% In the

casing, I made ( rectangular holes on the bottom. I used a small drill

 bit that is not wider than the thickness of the prongs. I drilled many

holes on a single line then a sharp knife to make up one rectanglethe si1e of the prong. I then inserted the plug through the holes and

glued it in from the inside using super glue.

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Submitted by:  Richard Marier  #(22324(5%

Ask your question about this circuit in the forum.

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How to Make a Simple LED Automatic Day/Night Lamp CircuitPosted by hitman

Although the concept may look pretty familiar and common, the main feature of the circuit is itslow current consumption and compactness.

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The power supply used here is a capacitive type, thus no transformer is incorporated making thecircuit very compact and fixable in any small corner of the particular premise.The use of LEs in place of a filament bulb makes the application very power economic andefficient. The proposed LE automatic day night lamp switch circuit diagram shows red LE beingused, however white LEs would suit the application better, as that would help illuminate the areabetter than the red LEs.The L! must be positioned such that the light from the LE does not fall on it, only the ambient

light which is to be sensed is re"uired to reach the L!.The circuit may be understood through the following points#The input $$% & mains suply is applied across the '% (hm resistor and the other neutral point.The '% (hms resistor helps to cancel out the initial surge or the voltage rush that might otherwisebe potentially harmful to the further stages of the circuit.The )(& or the varistor placed after the '% (hm resistor emhances the protection feature of theunit and grounds all surges that might sneak in after the '% (hm resistor.The capacitor drops the mains voltage current to lower levels and the bridge rectifier made up thefour diodes rectify the voltage to *.The '%%%u+ capacitor filters the rectified voltage and the smooth * is applied to the control circuitconsisting the two transistors.The first transistor is wired up as a comparator, which compares the potential difference across thevariable resistor and conducts when the voltage across it rises to saturation levels.The above rise in the voltage level takes place when the relevant magnitude of light falls on the L!surface. (nce the resistance of the L! falls below the set threshold due to higher ambient light,the transistor conducts.The collector of the above transistor instantly grounds the base of the next transistor and switches it(++.The associated LE lights connected to the collector of the second transistor are also immediatelyswitched (++.The opposite reaction takes place when the light over the L! falls below the set threshold,probably during dusk when the sun sets.The LEs light up again and remain switched ( until the day beaks and the ambient light over theL! reaches the set high threshold level.

The following figure shows a simple LE automatic day, night lamp circuit