Why small home appliance of the charger can't succeed in general?

Source: 2020 - 04 - 01 hits: hast time why small home appliance of the charger can not be generalized all sorts of small home appliance of the charger is not universal, because different small home appliance, the internal circuit and working principle of each are not identical, electric internal rechargeable battery varieties ( For example, some use lithium battery, use the nimh batteries) And voltage also may be different, so can't choose the universal charger all kinds of small home appliance. Let's take a look at several common charging circuit of small home appliance. 1 knife charges. 2 v nimh battery as a power drive small motor. Razor charging circuit is actually a simple low-power switching power supply. AC220V through single tube voltage oscillating circuit converts the high frequency alternating current (ac), after FR102 high frequency isolation transformer and diode rectifier to 1. 2 v nimh battery recharged. LED for charging indicator light, S power switch for the razor. The questioner referred to the charger, as shown in the above, but it is not the charger, because there is no rechargeable battery charger. Warm hands treasure is its internal heat storage data by the external power source heating, electricity, heat storage data slow release heat to warm hands. The charger's internal circuit as shown in the figure below. AC220V alternating current directly through the thermostat inside the warm hand treasure heating wire, make its heat. In other words, the charger ac output voltage. And of all kinds of small desk lamp and a flashlight charging, they often choose 4 v battery as a power source, this kind of small electrical charging circuit selection shown above the resistance capacity of buck circuit generally charge, its properties are constant current charging. Through capacitance F / 400 v input 1 step-down current limiting and rectifier bridge rectifier for 4 v battery, can charge the battery by the AC220V. After more than a few circuit can be seen that different small home appliance, the internal circuit and working principle is different, the built-in rechargeable battery and voltage is different also, so it is difficult to design a suitable for all kinds of small home appliance of the charger. Hypothesis does not consider the cost, this kind of charger plan, the internal circuit is also more complex, increase the failure rate of the product, very inconvenient when using, because of the universal charger output port, users need to choose the appropriate port charges, charging port selection error, may damage the appliance.