looking for a complete report on automatic change over switch. submission tomorrow. thanks
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Many electrical and electronic devices require direct current or alternating current for their operation. While AC power is made available primarily through the AC mains, DC power is available through the batteries. However, there are circumstances where there is a shortage of alternating current (through a power failure) or DC (due to limited battery life). To overcome this problem, we usually find many alternatives. For example, we can use generators or inverters in emergency cases to obtain alternating current when the power grid is disconnected. Similarly in the case of direct current, we can use a battery or an AC to DC power supply alternatively.
Automatic shift switch circuit principle:
This circuit is based on the principle of operation in bistable mode of 555 Timer. In this mode, the timer output is high or low depending on the trigger state and the reset pin. The timer output is connected to a transistor that acts as a switch, being on or off depending on the output of the timer. Two LEDs in series are used as load. In the event that the transistor is disconnected, the LEDs are powered by the AC-DC power supply, whereas in case the transistor is connected, the LEDs are powered by the battery.
Circuit diagram of the automatic shift switch: