Computers & Mobile Technology
HOW TO – USB to Nokia Safe Charger

Usb Charger DiagramRaphael writes “This simple project shows you how to make a USB powered Nokia cell phone charger. The advantage is that it weighs much less than the bulky AC adaptor, and can be used wherever you have a computer or a laptop. I use this thing all the time now!” Link.

16 thoughts on “HOW TO – USB to Nokia Safe Charger

  1. Before I read this Makezine blog entry I tried to make one of these for a Nokia 6102b. It didn’t work, I got the “Not Charging” message. I didn’t look at the USB power signal on an oscilliscope, but it ap[eared to be rock solid on 5.12V.

    This link’s suggestion didn’t make sense to me at all. All a diode would do is provide a ~0.5V drop of the voltage signal at the phone. I tried it anyway, with three little diodes in parallel (just in case one couldn’t handle the 350 mA of the expected charge current). It wouldn’t charge. I was getting 4.5V at the phone, which means the diodes were providing a voltage drop of ~0.6V.

    I then hooked the USB cable up to a variable power supply and found that the phone would start charging when the power supply was at 5.2V, and would stop when it went down to about 5.09V. Given the 0.6V drop across the diodes this means that the phone happily charges at 4.6V (at 350mA!) but not 4.5V (2mA) — much more sensitive than I expected, but not too suprising.

    I pulled the diodes out and replaced them with a little 333uF dielectric capacitor pulled off of a fried video card, connected across the +5 and GND (red and black) wires of the USB cable, down near the phone side of the cable. Now the USB charging cable works great.

    A capacitor across the power supply tends to reduce noise spikes on the power signal. When it comes to electrostatic filters they work well for mid and low-frequency spikes (kHz – Hz).

  2. I own various phones, and their charging status on USB is as follows

    Nokia N73 – Charges really well
    W800i – Optimised charging (just like wall adapter)
    W700i- Optimised charging (just like wall adapter)
    W610i-Optimised charging (just like wall adapter)
    Nokai 3230- Shows “Not charging”

    On checking the voltages of wall adapters, The one on Nokia 3230 had 6v, while all others were less than 5.7V.
    Probably thats why older phones like 3230 do not charge.

  3. fyi, add a 2-5 ohm resistor in series (for current limiting) and *all* new nokia phones (with the mini charge plug) will charge straight from USB (5V)

  4. Yes i have the same problem with a nokia 6120 with mini charge plug and it was fixed with the 5 ohm resistor in the 5 volts output.
    (I use a regulator using a lm317 in order to trim the output voltage)

  5. Yes i have the same problem with a nokia 6120 with mini charge plug and it was fixed with the 5 ohm resistor in the 5 volts output.
    (I use a regulator using a lm317 in order to trim the output voltage)

  6. Yes i have the same problem with a nokia 6120 with mini charge plug and it was fixed with the 5 ohm resistor in the 5 volts output.
    (I use a regulator using a lm317 in order to trim the output voltage)

  7. i tried with nokia 5200 it works but doesn’t work with nokia 3230 phone. could you please help me to make a usb charger working for 3230 nokia?

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