Archive for the ‘Lighting Circuits’ Category

PWM lamp dimmer using NE555

PWM lamp dimmer. A simple and efficient PWM lamp dimmer using timer IC NE555 is discussed in this article. Yesterdays linear regulator based dimmers can only attain a maximum efficiency  of 50% and are far inferior when compared to the PWM based dimmers which can hit well over 90% efficiency. Since less amount of power is wasted as heat, the switching elements of PWM dimmers require a smaller heat sink and this saves a lot of size and weight. In simple words, the most outstanding features of the PWM based lamp dimmers are high efficiency and low physical size. The…

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LED driver IC

MP3302 MP3302 is a boost converter IC specifically designed for LED drive applications. The MP3302 can drive 27 LEDs (9 strings of 3 white LEDs in series) from a Lithium ion battery. The IC has internal power MOSFETs for driving the LEDs and has an efficiency of 88%. Switching frequency is 1.3MHz and the internal current limit is 1.33A. Other features of the MP3302 are open load shut down, thermal shut down, under voltage lock out etc. Applications of Mp3302 are LED back lights, LED based lighting gadgets etc.  Functional block diagram of the MP3302 is shown below (Fig1). The…

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LED driver circuit

CAT3603. CAT3603 is a three channel charge pump LED driver IC from Catalyst Semiconductors that can be operated in either LDO mode or fractional mode. The IC can deliver 30mA per channel and can be operated from an input voltage range of 3 to 5.5V DC. CAT3063 has a quiescent current as low as 0.1uA and this makes it suitable for battery powered applications. The operating frequency is 1Mhz  which makes it possible to use small capacitors. Another features are soft start, current limiting, high efficiency (90%)  and short circuit protection. Applications of this IC are hand held devices, LCD…

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LED lamp circuit from scrap

Power saving LED lamp from your scrap box. This circuit is designed by Mr Seetharaman Subramanian and we are very glad to publish it here. In this article he is showing a method to convert a broken/defunct CFL into a LED based power saving light. This is just a LED lamp circuit that can be operated from the mains voltage. A string of five LED is driven using a capacitive transformer less power supply. In the circuit 0.47uF/400V Polyester capacitor C1 reduces the mains voltage. R1 is a bleeder resistor which drains the stored charge from C1 when the AC…

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Automatic night light

Automatic night light circuit Description. A cheap and simple automatic night light using few transistors and NE555 timer is shown here. The circuit will automatically switch on the AC lamp when night falls and the lamp will be automatically switched off after a preset time. The working of this night light circuit very simple. An LDR is used as the sensor here. At day time the resistance of the LDR will be low and so do the voltage drop across it, the transistor Q1 will be in the conducting mode. When darkness falls the resistance of LDR increases and so…

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Mains operated blinking LED

Description. The circuit diagram of a blinking LED that can be operated from the mains supply is shown here. The working of this circuit is as follows. When mains power is switched ON the capacitor C2 charges through resistor R1 and diode D1. When the voltage across the capacitor becomes greater than 32V ( break over voltage of diac DB3) the diac conducts making  the LED blinks and  capacitor C1 discharges through the LED.This cycle repeats again and again . Circuit diagram. Notes. 230V is potentially dangerous , be very careful while handling this circuit. The timing  of this circuit…

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Mains Operated LED Circuit

This is a modified version of the circuit Super bright LED Night Light published here. This circuit is submitted by Mr. Seetharaman and its full credit goes to him. This is the circuit of a well tried and reliable 230 Volt AC mains operated 24 LEDs (super bright 50mA LEDs). While practically compare the brightness between this circuit and 11watts tube, the LED light is much better. The layout is made in such a way, you get uniform illumination. A photograph of the cicuit is also given in this post.

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Automatic LED Emergency Light-Modified Version

Hi All Readers of CircuitsToday, As there is serious discussions going on about our previous Automatic LED Emergency Light Circuit using LM 317, Mr.Seetharaman has come up with a modified version of the same which answers many of the doubts raised in our Comments section. Note: Mr.Seetharaman has developed a new version of Automatic LED emergency light. This one is more simple,more efficient and uses minimum components. Take a look: Simple Emergency Lamp Circuit Here follows Seetharaman’s Description about the Modified Automatic LED Emergency Light using LM 317. Dear John Since there were lots of doubts from our readers on…

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24V flasher circuit

Description. The circuit shown here works from 24V DC and can flash two 24V bulbs alternatively. The circuit is nothing but an astable multivibrator operating at 1Hz and 50% duty cycle. The lamp to be flashed is connected in place of the collector resistor (Rc) of a typical design. 2N3055 transistors which are well known for their ruggedness are used here. They can handle collector currents up to 10A. So a wide range of lamps (in terms of wattage) can be connected to this circuit. Circuit Diagram. Notes. Assemble the circuit on a good quality PCB. Use 24V DC for…

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Powerful LED flasher

Description. This is the circuit diagram a powerful LED flasher. High power LEDs are very common in the market now and a 1W high power LED is used here. Transistors Q1 and Q2 are wired as an oscillator which produces positive pulses of width 20ms @ ½ Hz. Transistor Q3 and MOSFET Q4 inverts this pulse and MOSFET Q5 drives the LED D1. Circuit diagram . Notes. LED D1 is a 1W high power LED. Capacitors C1 and C2 must be rated 10V. Circuit can be powered from two AA cells connected in series. The peak LED current is set…

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