Comments on: USB LED Lamp circuit. http://www.circuitstoday.com/usb-lamp-circuit An Authentic Resource on Electronics Wed, 08 Feb 2012 02:09:28 +0000 hourly 1 http://wordpress.org/?v= By: LAW http://www.circuitstoday.com/usb-lamp-circuit#comment-24460 LAW Mon, 04 Apr 2011 13:05:10 +0000 http://www.circuitstoday.com/?p=160#comment-24460 It works when I give 5V power supply but it doesnt work when I plug into the usb port It works when I give 5V power supply but it doesnt work when I plug into the usb port

]]> By: LAW http://www.circuitstoday.com/usb-lamp-circuit#comment-24459 LAW Mon, 04 Apr 2011 13:02:17 +0000 http://www.circuitstoday.com/?p=160#comment-24459 I have made the above usb lamp. The lights cannot be turned on when I use 2.4V rechargable battery, however, it is on when I use 3.6 recharable battery. Besides, when I plug the usb lamp into computer's usb port, it doesnt work..why is it like that? and thanks for your design =) I have made the above usb lamp.
The lights cannot be turned on when I use 2.4V rechargable battery, however, it is on when I use 3.6 recharable battery.
Besides, when I plug the usb lamp into computer’s usb port, it doesnt work..why is it like that?

and thanks for your design =)

]]> By: Seetharaman http://www.circuitstoday.com/usb-lamp-circuit#comment-22160 Seetharaman Thu, 17 Mar 2011 17:12:56 +0000 http://www.circuitstoday.com/?p=160#comment-22160 Hi Kailash add one more 1N4007 in series with D2 then the constant current output at Q1 collector will be 30mA . Two Nicad cells fully charged voltage will be 2.64 volt. Connecting the LEDs in series the requirement will be 5.2 volts, which 2 cells cannot supply hence they will not glow. Connect both the LEDs in parallel, then it will work as each requires minimum 2.6 volt to glow. Rechargeable battery is the back up for the LEDs during power failure. The above circuit is not meant for supplying USB voltage to computer during power failure. Hi Kailash add one more 1N4007 in series with D2 then the constant current output at Q1 collector will be 30mA . Two Nicad cells fully charged voltage will be 2.64 volt. Connecting the LEDs in series the requirement will be 5.2 volts, which 2 cells cannot supply hence they will not glow. Connect both the LEDs in parallel, then it will work as each requires minimum 2.6 volt to glow. Rechargeable battery is the back up for the LEDs during power failure. The above circuit is not meant for supplying USB voltage to computer during power failure.

]]> By: kailash http://www.circuitstoday.com/usb-lamp-circuit#comment-22017 kailash Wed, 16 Mar 2011 11:08:24 +0000 http://www.circuitstoday.com/?p=160#comment-22017 how many diodes and rechargeable batteries in this diagram are required purpose ? how many diodes and rechargeable batteries in this diagram are required purpose ?

]]> By: Akash mehta http://www.circuitstoday.com/usb-lamp-circuit#comment-9580 Akash mehta Tue, 12 Oct 2010 16:06:21 +0000 http://www.circuitstoday.com/?p=160#comment-9580 Where we hav to connect d usb? How desktop can b operated with 5volt battery used in dis circuit? Plz send me some reply. Where we hav to connect d usb? How desktop can b operated with 5volt battery used in dis circuit? Plz send me some reply.

]]> By: adam http://www.circuitstoday.com/usb-lamp-circuit#comment-5810 adam Sun, 14 Mar 2010 15:35:02 +0000 http://www.circuitstoday.com/?p=160#comment-5810 you can't connect the LED direct --without current limiting resistor--to the battery you can’t connect the LED direct –without current limiting resistor–to the battery

]]> By: admin http://www.circuitstoday.com/usb-lamp-circuit#comment-4598 admin Fri, 13 Nov 2009 09:11:47 +0000 http://www.circuitstoday.com/?p=160#comment-4598 battery B1 provides the back up power battery B1 provides the back up power

]]> By: Niranjan http://www.circuitstoday.com/usb-lamp-circuit#comment-4319 Niranjan Sat, 31 Oct 2009 12:05:07 +0000 http://www.circuitstoday.com/?p=160#comment-4319 Please tell me, why we use battery b1 in USb lamp circuit....? Please tell me, why we use battery b1 in USb lamp circuit….?

]]> By: TONY http://www.circuitstoday.com/usb-lamp-circuit#comment-2627 TONY Thu, 14 May 2009 17:02:25 +0000 http://www.circuitstoday.com/?p=160#comment-2627 Umm if the power is down.. is the computer also.., do not take me wrong, great idea and all.. but if the power goes out and by chance the phone line is still live take the lamp off the usb and use it on the phone line ;) Umm if the power is down.. is the computer also.., do not take me wrong, great idea and all.. but if the power goes out and by chance the phone line is still live take the lamp off the usb and use it on the phone line ;)

]]> By: zhel http://www.circuitstoday.com/usb-lamp-circuit#comment-2312 zhel Tue, 03 Mar 2009 01:30:40 +0000 http://www.circuitstoday.com/?p=160#comment-2312 can you please explain farther the flow of this circuit in a USB lamp can you please explain farther the flow of this circuit in a USB lamp

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