Powerful LED flasher

john December 10, 2009 2 Comments
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...
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8 function christmas lamp

john September 24, 2009 26 Comments
Description. This 8 function serial Christmas lamp controller is based on the IC UTC 8156 from Unisonic. Specially designed for the same purpose, the UTC 8156 can control the four lamps in 8 modes namely waves, sequential, slo-gol, chasing/flash, slow fade, twinkle/flash, steady ON and auto scan. Control signals for controlling the lamps will be available at pin 12 to pin 15 of the IC. SCRs are used to drive the lamps according to these control signals. Circuit diagram....
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Super bright LED night light

john October 15, 2010 30 Comments
Description. Here is the circuit diagram of a super bright LED night lamp that can be operated from the mains supply. Bridge D1 is used to rectify the AC mains voltage. The capacitor C1 and resistor R1 forms the current limiting circuit. 10 ultra bright white LEDs are wired in series to produce the required light. The n-channel FET Q1(ZVN 2106) is used to automatically switch the lamp OFF at full light. The photo cell resistance is set to...
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Versatile emergency lamp.

john September 15, 2009 4 Comments
Description. Here is the circuit diagram of a very versatile emergency lamp that can be operated in two modes (flasher and dimmer). The circuit is based on the dual op-amp IC LM358.The dimmer and flasher mode can be selected by using the switch S1. In the dimmer mode the output of IC1b will be pulses whose width can be adjusted by using POT R3. Transistors T1 and T2 forms the driver stage which drives the lamp L1 according to...
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Temperature controlled LEDs

john August 18, 2009 23 Comments
Description. The circuit is nothing but two LEDs (D1 and D2), whose status are controlled by the temperature of the surroundings. The famous IC LM35 is used as the temperature sensor here. Output of LM35 increases by 10mV per degree rise in temperature. Output of LM35 is connected to the non inverting input of the opamp CA3130.The inverting input of the same opamp can be given with the required reference voltage using POT R2. If the reference voltage is...
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Lamp flasher using LM317

john April 7, 2010 7 Comments
Description. Here is a very useful lamp flasher circuit using the famous adjustable voltage regulator IC LM317T. LM317 can source up to 1A of current and so up to 12W lamps can be used with this flasher. Such a circuit finds huge application in automobiles. The frequency of the flashing depends on the value of resistors R1 to R3 and capacitors C2 to C4.With the given values; the flashing rate is around 5 flashes per second. Circuit diagram. Notes....
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Lamp flasher using LM395

john April 7, 2010 No Comments
Description. This powerful lamp flasher circuit is ideal for use in automobiles. The circuit is based on IC LM395 (also known as super transistor) which is a very powerful integrated monolithic power transistor with features such as thermal overload protection, current limiting etc. In fact this IC is almost indestructible.The IC can handle currents up to 1A and switch 40V in less than 500 nano seconds. Resistance R1 and capacitor C1 determines the frequency of flashing. With the stated...
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Photocell based night light

john July 9, 2009 21 Comments
Description. Many automatic night light circuits had been published here. This one uses a photocell for detecting the light intensity. At full light the resistance of the photocell will be few ten ohms and at darkness it will rise to several hundred ohms. The IC1 uA741 is wired as a comparator here. At darkness the resistance of photocell increases and so the voltage at the inverting input of the IC1 will be less than the reference voltage at the...
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Simplest lamp flasher circuit.

john June 4, 2009 19 Comments
Description. This is a very simple lamp flasher circuit that uses only three components (a capacitor, relay and one resistor) other than the lamp. The working of the circuit is very straight forward. When the power is switched ON the capacitor C1 charges through the resistor. When the voltage across the capacitor is sufficient, the relay switches ON and the lamp connected via the normally open contact of the relay glows. The relay remains energized until the capacitor discharges...
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Automatic emergency light

john May 19, 2009 1 Comment
Description. This is a simple automatic emergency light which remains OFF when the mains power is available and switches ON when there is a power failure. When mains power is available, it is stepped down by transformer T1, rectified by diodes D1&D2, filtered by the capacitor C2 and regulated by the 9V regulator IC 7809 to produce 9V DC. This 9V DC is used for charging the battery. While the battery is charging the diode D3 is forward biased...
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