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Normally cell batteries have a shelf life of 2 to 5 years under normal use . After that time we have to replace them . Nowadays there replacement batteries which are cheap, but these batteries last for much less cost only months. An easy solution is to use batteries in a circuit that requires less current , we can use them for lighting LEDs .  How to Reuse Old Cell Battery for LED lighting 

The XM- Lamp LED can be regarded as the highest performance LED , solid state single LED that is capable of producing ultra-bright light intensities . These LED s offer a unique combination of high efficiency , it is able to efficiently provide 1000 lumens 100 lumens per watt at 3 , 5 mm x 5 mm. The circuit described here can be used for applications in residential lighting and automotive LED s should be mounted on suitable heat sinks for optimal performance . For more information on this, you can consult the datasheet in the link below . Create XLamp XM-LED Circuit Diagram Specifications : Size ( mm x mm ) 5 x 5 Maximum unit current ( A) 3 Maximum power ( W) 10 Light output Up to 1040 lm 10 W @ Typical forward voltage ( V) 3.1 Viewing angle ( degrees ) 125 ANSI binning Thermal Resistance ( ° C / W ) 2.5 Yes Reflow - solderable - JEDEC J -STD - 020C - compatible RoHS and REACH - compliant Yes UL recognized component ...

LM3914. The heart of this circuit is the LM3914 from national semiconductors. The LM3914 can sense voltage levels and can drive a display of 10 LEDs in dot mode or bar mode. The bar mode and dot mode can be externally set and more than one ICs can be cascaded together to gat an extended display. The IC can operate from a wide supply voltage (3V to 25V DC). The brightness of the LEDs can be programmed using an external resistor. The LED outputs of LM3914 are TTL and CMOS compatible. Description. In the circuit diagram LEDs D1 toD10 displays the level of the battery in either dot or bargraph mode. Resistor R4 connected between pins 6,7 and ground controls the brightness of the LEDs. Resistors R1 and POT R2 forms a voltage divider network and the POT R2 can be used for calibration. The circuit shown here is designed in order to monitor between 10.5V to 15V DC. The calibration of the circuit can be done as follows. After setting up the circuit connect a 12V DC source to the input. Now adju...

This circuit was designed as a warning flasher to alert road users to dangerous situations in the dark. Alternatively, it can act as a bicycle light (subject to traffic regulations and legislation). White LEDs only are recommended if the circuit is used as a bicycle front light (i.e. for road illumination) and red LEDs only when used as a tail light. During the day, the two 1.6-V solar cells charge the two AA batteries. In darkness, the solar cell voltage disappears and the batteries automatically power the circuit.  High-intensity LED Warning Flasher Circuit Diagram The flash frequency is about one per second and the LED on-time is about 330 ms. The duty cycle should enable the batteries to power the circuit over night. The circuit is composed of three parts. Under normal daylight conditions the batteries are charged through diode D4. In darkness, pnp transistor T1 is switched on, supplying battery current to the second part, a low-frequency oscillator comprising T2 and T3.The thi...

Build a 10 LED Bar Dot VU meter circuit based LM3915. It differs in many respects from other applications on the same chip. The circuit is intended for those who want a VU meter that is connected directly to the output of an power amplifier.  10 LED Bar Dot VU Meter Circuit based LM3915 Circuit Diagram It’s possible to adjust the sensitivity to work with amplifiers that have different output power, you just need to change the value of R1 according to Table 1. In case you did’n find the exact resistor value, then choose the next standard value (for example if you cannot find 33K ohm, then find the 36K ohm), or if you want maximum accuracy you need to put resistors in series or in parallel to achieve the correct value.   You can use various types of LEDs (round or square) to get the visual and aesthetic result you want. The switch S1 will allow you to choose whether VU meter will work as a bar or one by one (dot). In position ON [closed switch], the LED operation is Bar, while i...

Thanks to their high light output and long lifetimes, a white LED is an excellent choice as a replacement for the incandescent bulb in a penlight torch. However, there is a ‘but’. Depending on the current level, white LEDs need a voltage of 3 to 4 V. You thus need a penlight with at least three batteries, which is not exactly what you can call compact. Fortunately, this problem can be remedied using a simple adapter circuit.   The design described here allows a white LED to be operated from a single 1.5-V battery. It consists of a simple step-up converter and an oscillator. If the circuit is built using SMD components as much as possible, it will not be difficult to fit everything into the torch.  The actual step-up converter consists of L1 and T1. The coil is wound on an EP7 core, which consists of a spool, two core halves (T-38 core material) and a clip/screen. It is available from Farnell, among others. Wind 17 turns of 0.5-mm enamelled copper wire on the spool. If you make the wind...

Start making a simple program in which we in assembly code using PIC 16F877A to turn on and off an LED by pressing a button as shown in the diagram. We will use two ports of the PIC 16F877A, port B and port D, declare the B port as input and the D port will be configured as an output. In the graph we can see that the pin RB0 is set button and a resistor in a pull-up configuration, when you are not pressing the button it gets a high (5V) to the RB0 input and when pressed he gets a level low (0V). In the output RD0 to turn on the led its output should be at a low level so when developing the program in assembler we test the pin B0 and if a high level put a high value on the output RD0 that will keep off LED, otherwise put a low value on the output RD0 which will cause the LED lights. ASSEMBLER PROGRAM FOR PIC 16F877A To make the program use the MPLABX 2.0 Open the IDE MPLABX program. We click file, select New Project ... In window "Select Project" emerging select "Microchi...

Using a few diodes and a LED, you can make a nice indicator as shown in associated schematic diagram that can be used for a lot of applications (with a bit of luck). It’s quite suitable for use in series with a doorbell or thermostat (but don’t try to use it with an electronically con-trolled central-heating boiler!). This approach allows you to make an attractive indicator for just a few pennies. The AC or DC current through the circuit causes a voltage drop across the diodes that is just enough to light the LED. As the voltage is a bit on the low side, old-fashioned red LEDs are the most suitable for this purpose. Yellow and green LEDs require a somewhat higher forward voltage, so you’ll have to first check whether it works with them. Blue and white LEDs are not suitable. You also don’t have to use modern high-efficiency types (sometimes called ‘2-mA LEDs’ or ‘3-mA LEDs’). If a DC current flows through the circuit and the LED doesn’t light up, reverse the plus and minus leads. Bridg...

The LM3909 is an integrated circuit (IC) which will flash a light-emitting diode (LED). Using only two extra components and a battery, the circuit is cheap and has a very low current drain from a 1.5 V cell. The circuit can be used as a novelty flasher, an indicator for a dummy alarm bell box, or it could be attached to a torch so that it could be found easily in the dark! The simple circuit Assembly The circuit can be built on a small piece of Veroboard (the piece shown in Figure 2 measures 15 holes by 10 strips). Using such a board, follow these instructions. 1. Depending on how far away you want the LED from the circuit board, solder a length of insulated wire to each lead of the LED. Use different colours of insulation – say, red and black, connecting the red lead to the anode (a) lead (the longer one) of the LED, and the black one to the cathode (k). Figure 2 shows these leads. 2. Cut the copper tracks as shown in Figure 2, using a 3 mm (1⁄8 inch) diameter drill, rotated between t...