Page 1 of 2 12 LastLast
Results 1 to 20 of 26

Thread: Need technical help in some electronic circuity

  1. #1

    Talking Need technical help in some electronic circuity

    Hi Guys,

    I am building a portable USB charger (Battery extender) using 5V, 1A output positive Voltage regulator. How do I bump up the output current to 2A at least? Help appreciated.. Thanks..

  2. #2

    Default Re: Need technical help in some electronic circuity

    pullup resistors or ICs to do pull up.....not sure if power amp can do such things too........

  3. #3

    Default Re: Need technical help in some electronic circuity

    You'll need to change the regulator to a 5V, 2A device.
    Which device are you using currently?
    Are you trying to use the PC/notebook USB port?

  4. #4
    Senior Member
    Join Date
    Jan 2002
    Location
    South Pole with Penguin
    Posts
    5,270

    Default Re: Need technical help in some electronic circuity

    and becareful, dont fried your USB port, esp for laptop
    We are HDD of PC & FT are MB add to storage;
    so PC never hangs with enormous storage capacity - LKY

  5. #5
    Senior Member
    Join Date
    Sep 2004
    Location
    Cons digger.
    Posts
    3,924

    Default Re: Need technical help in some electronic circuity

    Quote Originally Posted by enghong17
    pullup resistors or ICs to do pull up.....not sure if power amp can do such things too........
    pull up resistors?
    power amp?

    I think if you suggest current mirrors would be a better choice.

    but then tokrot is trying to draw 2A from a USB port. USB ports are typically spec to supply 1A max but not many are designed to this full spec, most give only 500mA or some give 1A but shared amongst all the ports. Overloading it will fry the port like what wai said. If you really want to squeeze 2A out you can use 2 USB ports from different root hubs.
    Last edited by yanyewkay; 13th March 2006 at 10:01 AM.
    “How fortunate for leaders that men do not think.” - Adolf Hitler

  6. #6
    Senior Member Pablo's Avatar
    Join Date
    Sep 2004
    Location
    Blue/Green Planet
    Posts
    1,854

    Default Re: Need technical help in some electronic circuity

    A regulated 5V supply can not be re regulated to 5V due to regulator IC's requite a higher input voltage
    than their output voltage.

    2A out of a USB port (or ports) might be looking for trouble.

    Cheers
    Last edited by Pablo; 13th March 2006 at 11:28 AM.
    Time, is an effortless construction :)

  7. #7

    Default Re: Need technical help in some electronic circuity

    Quote Originally Posted by yanyewkay
    pull up resistors?
    power amp?

    I think if you suggest current mirrors would be a better choice.

    but then tokrot is trying to draw 2A from a USB port. USB ports are typically spec to supply 1A max but not many are designed to this full spec, most give only 500mA or some give 1A but shared amongst all the ports. Overloading it will fry the port like what wai said. If you really want to squeeze 2A out you can use 2 USB ports from different root hubs.

    Oops....din read properly.....

    Tokrot, why do u need circuitary to bump up ur current to 2A when there are 5V 2amp voltage regulatore? the 7405 has variants that provides 2amps. And as the others said, its not a totally good idea.....

  8. #8
    Senior Member
    Join Date
    Jan 2002
    Location
    Northwest
    Posts
    5,011

    Default Re: Need technical help in some electronic circuity

    Quote Originally Posted by tokrot
    Hi Guys,

    I am building a portable USB charger (Battery extender) using 5V, 1A output positive Voltage regulator. How do I bump up the output current to 2A at least? Help appreciated.. Thanks..
    You better give a clearer description of what you are trying to make or else you won't get the correct technical advice.

    1. What is the device you are charging?
    2. What kind of battery does the device have, and what's the battery capacity?
    3. What is your power source? USB port, battery pack, or AC mains?

    For regulator ICs with variable output voltage set by feedback resistors, the output current capability can be increased by adding power transistors with the required current rating. The transistor is usually NPN in an emitter follower configuration, with the power source connected to the collector, the regulator output connected to the base, and the feedback voltage taken fromt he emitter, whic is also the output source tot he circuit being powered.
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  9. #9
    Senior Member
    Join Date
    Sep 2004
    Location
    Cons digger.
    Posts
    3,924

    Default Re: Need technical help in some electronic circuity

    Quote Originally Posted by roygoh
    You better give a clearer description of what you are trying to make or else you won't get the correct technical advice.

    1. What is the device you are charging?
    2. What kind of battery does the device have, and what's the battery capacity?
    3. What is your power source? USB port, battery pack, or AC mains?

    For regulator ICs with variable output voltage set by feedback resistors, the output current capability can be increased by adding power transistors with the required current rating. The transistor is usually NPN in an emitter follower configuration, with the power source connected to the collector, the regulator output connected to the base, and the feedback voltage taken fromt he emitter, whic is also the output source tot he circuit being powered.
    the problem with his requirement (if i read properly) he has 5v in from USB port and he wants 5V out from USB port but 2A out.

    If he has 12V input it will be so much easier to work with.
    “How fortunate for leaders that men do not think.” - Adolf Hitler

  10. #10
    Senior Member
    Join Date
    Sep 2004
    Location
    Cons digger.
    Posts
    3,924

    Default Re: Need technical help in some electronic circuity

    Quote Originally Posted by enghong17
    Oops....din read properly.....

    Tokrot, why do u need circuitary to bump up ur current to 2A when there are 5V 2amp voltage regulatore? the 7405 has variants that provides 2amps. And as the others said, its not a totally good idea.....
    it's a convenient power supply source. (almost) every computer has a USB port with 5v ready.
    “How fortunate for leaders that men do not think.” - Adolf Hitler

  11. #11
    Senior Member
    Join Date
    Jan 2002
    Location
    Northwest
    Posts
    5,011

    Default Re: Need technical help in some electronic circuity

    Quote Originally Posted by yanyewkay
    the problem with his requirement (if i read properly) he has 5v in from USB port and he wants 5V out from USB port but 2A out.

    If he has 12V input it will be so much easier to work with.
    If he is drawing power from USB port, I don't see why he needs a 5V regulator, since USB power is already regulated at 5V. Another problem is the 2A current requirement. USB ports can supply up to 500mA in theory. You might be able to draw more if the port does not have any power protection that would trip it at 500mA, but it is risky to do so.
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  12. #12
    Member
    Join Date
    Apr 2004
    Location
    In my own world
    Posts
    1,314

    Default Re: Need technical help in some electronic circuity

    This kind of thing buy off the shelves better, save your time and money. Get a external powered USB hub.

  13. #13
    Senior Member Pablo's Avatar
    Join Date
    Sep 2004
    Location
    Blue/Green Planet
    Posts
    1,854

    Default Re: Need technical help in some electronic circuity

    If the USB port is in a laptop, then drawing 2A from it is going to :-

    1) Lower the battery life for on time of the laptop

    2) Increase heat generated in the laptop regulation circuitry

    3) Put stress on the laptop 5V regulation circuitry.

    If it is a laptop, remember that the battery is already way above 5V and is regulated to 5V (amongst other voltages).

    Dropping a supply (battery) from 10.8V or more, to 5V generates heat. The more current you draw at 5V creates more heat.

    I don't think laptops (and most PC motherboards) were designed to supply a random 5V at 2A.

    Just my thought
    Time, is an effortless construction :)

  14. #14

    Default Re: Need technical help in some electronic circuity

    You're gonna kill your comp. By design, USB root nodes are supposed to provide max 500mA and bus powered hubs can do 100mA. If you try to do 2A you are surely going to kill it.

    I don't have the USB hardware specs with me right now, but I remember these numbers clearly. Google it and you'll get them.

  15. #15
    Senior Member
    Join Date
    Jan 2002
    Location
    Northwest
    Posts
    5,011

    Default Re: Need technical help in some electronic circuity

    Hehe..all these advice when it is not even clear what tokrot is trying to build in the first place.
    As complexity rises, precise statements lose meaning and meaningful statements lose precision.

  16. #16

    Default Re: Need technical help in some electronic circuity

    a workaround is to tap from the IDE drive power cables. Use the yellow cable for 5V and black cable for ground.

    but be careful about the 5V output, as the current is extremely high, at least 25A or more. see the spec labels pasted on the PSU of the PC. one brief short circuit on the 5V supply, and the entire PC is tripped. so be sure u know what u r doing...
    Last edited by user12343; 13th March 2006 at 04:49 PM.

  17. #17
    Senior Member Pablo's Avatar
    Join Date
    Sep 2004
    Location
    Blue/Green Planet
    Posts
    1,854

    Default Re: Need technical help in some electronic circuity

    Hi,

    As Roy mentioned, "we don't really know what is being sought here".

    For the sake of it. Here is a 3 terminal regulator IC that will handle 5v at 2A easily (with heatsink).

    The 2 capacitors are essential (they help stability). Should be Tag Tan types if you can get them.

    The IN4002 power diode is to protect from shorts.



    For this type of circuit (regulator) I would suggest at least 4 volts higher input than the required 5v output.

    Yes, this was drawn using windows paint

    Cheers
    Time, is an effortless construction :)

  18. #18

    Default Re: Need technical help in some electronic circuity

    WOW, guys! I didn't know get so many replies... I am grateful! Thanks guys!

    Actually I was building a 9V DC USB portable charger for my Creative Zen Vision:M. I own two creative products. Other one is the Zen Micro. Both wall plugin adapters are as follows

    1) Creative Zen Vision:M using 5V, 2.4A
    2) Creative Zen Micro using 5V, 1A

    I am using LM7805 5V regulator, 1A output. As expected, it works only for for Zen Micro but not vision:M
    .
    So may is it to pump up the current using capacitors possible or get other voltage regulator of 5v, 2A specs? I can't find any which gave exactly at 2.4A. How do I know the mininal current needed to activate the charging for my vision M?

    The USB ports uses about 500mah as according to Windows XP in control panel.

    Quote Originally Posted by thomas_lkt
    You'll need to change the regulator to a 5V, 2A device.
    Which device are you using currently?
    Are you trying to use the PC/notebook USB port?
    Quote Originally Posted by roygoh
    If he is drawing power from USB port, I don't see why he needs a 5V regulator, since USB power is already regulated at 5V. Another problem is the 2A current requirement. USB ports can supply up to 500mA in theory. You might be able to draw more if the port does not have any power protection that would trip it at 500mA, but it is risky to do so.
    Portable charger or battery extender...

    Quote Originally Posted by enghong17
    Oops....din read properly.....

    Tokrot, why do u need circuitary to bump up ur current to 2A when there are 5V 2amp voltage regulatore? the 7405 has variants that provides 2amps. And as the others said, its not a totally good idea.....
    err.. actually I was using LM7805 which gives you a standard 5V, 1A output. This may not be sufficient for my Vision:M which uses 5V and 2.4A. So I was thinking of using other NTE1934 which gives 5v, 2A but got some design restriction..

    Quote Originally Posted by Pablo
    Hi,

    As Roy mentioned, "we don't really know what is being sought here".

    For the sake of it. Here is a 3 terminal regulator IC that will handle 5v at 2A easily (with heatsink).

    The 2 capacitors are essential (they help stability). Should be Tag Tan types if you can get them.

    The IN4002 power diode is to protect from shorts.



    For this type of circuit (regulator) I would suggest at least 4 volts higher input than the required 5v output.

    Yes, this was drawn using windows paint

    Cheers
    Wow, piaolo! Thanks for the effort! But I was thinking the likelyhood for my Vision:M not charging could be due to insufficient current. But it could be otherwise. Thanks.

    Thanks again for all the guys who replied..

    here's the information for those who are interested

    http://www.hackaday.com/entry/1234000270029372/
    http://www.geocities.com/JDPetkov/Ha...wer/MC7805.pdf 5Vout, 1A
    http://www.hobbytron.com/NTE/specs/1...df/nte1934.pdf 5Vout, 2A
    Last edited by tokrot; 13th March 2006 at 09:54 PM.

  19. #19
    Member
    Join Date
    Jan 2005
    Location
    Singapore
    Posts
    1,095

    Default Re: Need technical help in some electronic circuity

    Quote Originally Posted by tokrot
    So may is it to pump up the current using capacitors possible or get other voltage regulator of 5v, 2A specs?
    You can pair the 7805 with a PNP power transistor to boost the current. Whether it's worth the hassle compared to getting a higher current regulator integrated as a small 3 pin device is another question.

  20. #20
    Senior Member
    Join Date
    Sep 2004
    Location
    Cons digger.
    Posts
    3,924

    Default Re: Need technical help in some electronic circuity

    chey.. say so earlier lah.. you have 9v supply.. parallel 2 pieces of 7805 will solve your problem. It's a cheapskate way, not highly recommended by many, but I use it all the time.

    I was under the impression that you wanted 5V 2A to be from the USB port

    Else under the 7805 spec sheet there's an example of adding a power transistor like what LittleWolf said to get 2A.
    “How fortunate for leaders that men do not think.” - Adolf Hitler

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •