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Homework Help: Modifying rectifier circuit to include LED indicator

  1. Dec 5, 2008 #1
    You bought a charger that does not have a charging satus indicator. Assuming that a regular rectifier circuit configuration (such as this: http://www.physics.udel.edu/~nowak/phys645/AC_circuits_files/image016.jpg ) is used for the charger, modify the rectifier circuit to have LED indicator(s) and explain how the modified circuit would work.

    3. The attempt at a solution

    - I'm not at all sure on this one. I was originally thinking to add an LED in series with the load and explain that the load (rechargeable battery) would block the current once it was charged, and that would cause the LED to shut off, but I don't think that is how rechargeable batteries work. Can someone please help me on this one?
  2. jcsd
  3. Dec 27, 2008 #2
    Once the battery recharge,the current flow through the circuit and the LED lighted isn't it ?
  4. Dec 28, 2008 #3
    I am not familiar with charging circuits. I just looked at the schematic, there is no way to stop charging the battery when it is full, I won't use this to charge.

    Is it true that when the battery is fully charged, it rise to a certain voltage. You need a voltage monitor to monitor this and shut off the charging circuit and turn on the LED.

    Look into Maxim catalog, maybe Linear technology. They have battery charging circuits. Read application articles before you do anything. I afraid if you use the circuit as shown, there is no current limiting and no shut off. You might blowup the battery at the minimum or catch on fire!!!

    You might even find off line switching regulator charger IC since there is a lot of transformerless charger already. As I said I have no experience but been going through enough data books online to know there are stuff around to do the job. After that, check DigiKey to order.
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