UP/DOWN FADING LED CIRCUITS

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These two circuits make a LED fade on and off. The first circuit charges a 100u and the transistor amplifies the current entering the 100u and delivers 100 times this value to the LED via the collector-emitter pins. The circuit needs 9v for operation since pin 2 of the 555 detects 2/3Vcc before changing the state of the output so we only have a maximum of 5.5v via a 220R resistor to illuminate the LED. The second circuit requires a very high value electrolytic to produce the same effect.

LM3909 LED flasher

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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!

USB POWER BOOSTER CIRCUITS

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As we all know, USB port can deliver 500mA Approximately. but sometimes we might need more than 500 mA for our external devices. in this case we don't have any solution rather than by a USB hubs that have an external power supply. but in here i will give you good solution for our technical people. this simple idea can help you,