I have an output voltage of 3V, 500MA switching power supply, would like to change the output voltage of 5V charger specific parts to change the value, such as feedback resistor, switch transformer (there are two).
Replace the output transformer can be, but must be the same with the resistance value should be no problem! 11
You are too general about your system in the end is a thing. The The Suggest you to simulate yourself. The This can be casually try
In the 3V side plus a capacitor, positive and negative level can not take the wrong capacitor does not explode Oh, it is estimated that only to about 4.2V
The 3V output into 5V output is relatively easy, and perhaps directly change the proportion of feedback resistance can be, and then not, the transformer output plus a few turns also get.
But the adapter to switch the power into a charger is too much trouble, because the charging current is the need for current limiting, or battery life will be greatly reduced or even directly burned. So be careful
Look at your circuit diagram is an electronic transformer schematic, is generally used to do energy-saving lamp power supply, the output is about 40KHZ AC, in order to change its output voltage can only be changed by changing the EE19 transformer turns
In order to maintain the overall performance of the switching power supply (mainly efficiency and ripple), it is best to increase or decrease the number of secondary winding turns of the transformer. If the window area is insufficient, you can reduce the diameter of a file, the other winding do not have to move. If you do not change the transformer, but only change the resistance of the sampling resistor, you can also adjust the output voltage in a small range. If the switching power supply performance requirements are not high, the load power is not large, non-batch production, you can adjust to emergency use.
