Mobile phone charger output voltage can also be coincidence
L now mobile phone penetration rate is nearly reach the level of a hand, and new phones emerge in endlessly.
So, we always have some at hand did not keep up with The Times the pace and out of cell phone charger.
The charger is lost feel pity, with it, also with not that many, and they are all 5 v output.
Around us need adapter power supply and many, but are not necessarily need the voltage of 5 v.
If the output voltage of your mobile phone into the voltage, we need the phone charger reemployment road will be more broad.
L is introduced in this paper how to make the appropriate changes to the output voltage of phone, making it qualified for new jobs l phone charger (
Hereinafter referred to as the charger)
Circuit is multifarious, convenient to change output voltage must have a premise: must have light coupling feedback element, has a light coupling components means that its secondary circuit voltage sampling element and the function of the voltage adjustment.
So we have to change the output voltage of the charger, first is about to see it is there light coupling, no light coupling is not in vain, this kind of fake goods not only changes the struggling, barely changed, the effect is not satisfactory.
L a shanzhai chargers, circuit boards can't see the light coupling, the charger is not changed.
2 l is a kind of sampling with resistance, triode for amplification of the charger.
The face of it, and its opposite.
Local enlarge figure 3 is a l l with triode amplifier of the charger, but its triode is SMT components, welding in reverse.
L 4 is the charger with operational amplifier components.
L those who have amplifier element and sampling resistance of charger, as long as the change of any a sampling resistance value can change the output voltage.
The charger as shown in figure 2 c, the output voltage is 5.
3 v, I want to used for transistor radio, it need to change it to 3 v, so the figure of C6 from 3.
1 to 6 k now.
5 k, then the output voltage, have been reduced to 3.
That is only a resistance to change, restructuring're done!
L is very simple, is not so easy to do it, the reason is: how do we know which two sampling resistance is the resistance?
L sampling resistor to find it is not difficult, it has the following features: n two sampling resistor is connected in series, resistance is generally kΩ
The order of magnitude;
N it usually ends up in low voltage power supply output;
N the middle point of it into the amplifier;
N the appearance of the two resistance, accuracy and other resistance for the most part is a little difference.
L find you identified & other;
Sampling resistance & throughout;
, you can also prepare a 5 ~ 10 times greater than its resistor in parallel with it, the best that connected with the anode voltage sampling resistor in parallel.
Sign after l connected electricity, use digital submission to the output voltage, output voltage with the charger of the original.
If have change, so congratulations you, sampling resistor you find the right.
To an appropriate value of resistance in parallel, in order to obtain the voltage you need.
L, however, please note: the low voltage change should be no problem.
If you want to change more, is not as high as I want to change change.
Because of this charger is switching power supply, circuit working in the flyback type, the higher the output voltage, switch of back pressure is higher.
So if it is possible to change the output voltage is too high will switch tube due to over-voltage breakdown!
L so it might be to 20% higher than the output voltage adjustable, that is: 5 v charger can change to 6 v or so you can't complain.
L no amplifier element and sampling resistor, only one regulator tube, voltage standard.
The only regulator tube for different voltage value can change the output voltage.