Automatic Changeover Switch Circuit Principle

This circuit depends on the guideline of bistable mode task of 555 Timer. In this mode, the Timer yield is either high or low contingent on the status of trigger and reset stick. The Timer yield is associated with a transistor which goes about as a switch, being on or off contingent on the Timer yield. Two LEDs in arrangement are utilized as a heap. If there should arise an occurrence of transistor being turned off, LEDs are driven by the AC-DC control supply while in the event of transistor being exchanged on, LEDs are driven by the battery.

Automatic Changeover Switch Circuit Diagram:

 

Automatic Changeover Switch Circuit Design:

Designing the circuit involves two basic parts –

1. Design of AC – DC Power Supply:

 It is the plan of an essential AC to DC control supply framework utilizing transformer and scaffold rectifier.

The initial step includes choice of the voltage controller. Since here, our prerequisite is to drive two LEDs in arrangement alongside a Schottky diode, we settle down with LM7809 voltage controller creating a voltage of 9V. Since info voltage to the controller must be in any event 12V, we settle down with an information voltage of about 20V.

The following stage includes choosing the transformer. Since essential voltage is 230V and required auxiliary voltage is about 20V, we can settle with a 230V/20V fundamental transformer.

The third step is the choice of diodes for extension rectifier. Since pinnacle voltage over the transformer auxiliary is around 28V, the all out PIV of the extension would be around 112V. Consequently we need diodes having PIV rating more than 112V. Here we select 1n4007 having PIV of about 1000V.

The last advance includes determination of channel capacitor. For a capacitor, crest voltage of 26V and least controller input voltage of 12V, the admissible swell is about 14V. The capacitance esteem is then determined by the recipe, C = I (Δt/ΔV), where I is entirety of tranquil current of voltage controller and required burden current. Substituting the qualities, we get an estimation of about 17uF. Here we select a 20uF electrolyte capacitor.

2. Plan of Bistable Multivibrator Circuit utilizing 555 Timer: 

At the point when a 555 Timer is arranged in bistable multivibrator; its yield is either high or low rationale flag. Here we utilize the basic rationale that when trigger stick is grounded, yield is a high rationale flag and when reset stick is grounded, yield is low rationale flag. Here the yield of 555 Timer is associated with the base of transistor BC547.

Programmed Changeover Circuit Operation: 

The circuit task initiates once the switch S1 is at any of its position. At the point when the switch S1 is at position 1, reset stick of the 555 Timer is grounded. Inside this reset stick is the reset stick of the SR Flip lemon and subsequently the yield of 555 Timer is a low rationale flag. Presently since base producer intersection of Q1 is turn around one-sided, it is in cut off position. The heap LEDs are associated straightforwardly to the yield of the voltage controller through the Schottky diode. Here is the place the activity of AC to DC control supply circuit comes to play. Air conditioning power is first ventured somewhere around the transformer and after that changed over to unregulated and fluctuating DC voltage by the scaffold rectifier. The AC swells from the fluctuating DC voltage is expelled by the channel capacitor. This unregulated DC voltage is then changed over into a managed DC voltage by the voltage controller.

At the point when switch S1 is at position 2, trigger stick of 555 Timer is grounded. This makes the yield of the 555 Timer be a rationale high flag. The base producer intersection of Q1 is accordingly forward one-sided and the transistor is headed to immersion, along these lines being in on position. Here we should note two things – First, the Schottky diode presently does not directs as the voltage contrast between both cathode and anode of the diode is zero, for example there is no potential contrast at the intersection. Besides, the LEDs are presently one-sided through the resistor and the transistor and driven by the battery voltage.

Utilizations of Automatic Changeover Switch: 

This circuit can be utilized as a home lighting framework with couple of changes.

It very well may be utilized to drive other DC loads like a DC engine of any electronic machine or other toy applications.

Constraints of this Circuit: 

This is a hypothetical circuit and may require few changes when actualized on PCB.