Bistable Flip Flop with relay

Here are two examples of bistable flip flops which can be toggled between states with a single push button. When the button is pressed, the capacitor connected to the base of the conducting transistor will charge to a slightly higher voltage. When the button is released, the same capacitor will discharge back to the previous voltage causing the transistor to turn off. The rising voltage at the collector of the transistor that is turning off causes the opposite transistor to turn on and the circuit remains in a stable state until the next time the button is pressed and released. More: Note that in the LED circuit, the base current from the conducting transistor flows through the LED that should be off, causing it to illuminate dimly. The base current is around 1 mA and adding a 1K resistor in parallel with the LED will reduce the voltage to about 1 volt which should be low enough to ensure the LED turns completely off.

The described circuit utilizes two bistable flip-flops, commonly implemented using transistors, to create a toggle mechanism controlled by a single push button. The circuit operates based on the charging and discharging behavior of a capacitor connected to the base of one of the transistors. When the push button is pressed, the capacitor charges, increasing the base voltage of the conducting transistor. This action turns the transistor on, allowing current to flow through the circuit.

Upon releasing the button, the capacitor discharges back to its previous voltage, which turns off the conducting transistor. The discharge causes a voltage rise at the collector of the transistor that has just turned off. This voltage change is sufficient to turn on the second transistor, thereby maintaining the circuit's state until the push button is activated again.

In the LED circuit configuration, the base current flowing through the conducting transistor also passes through an LED that is intended to be off. This results in a dim illumination of the LED due to a base current of approximately 1 mA. To ensure the LED is fully off when intended, a 1K ohm resistor can be added in parallel with the LED. This resistor effectively reduces the voltage across the LED to around 1 volt, thus preventing it from illuminating and ensuring that it remains off during normal operation.

Overall, this bistable flip-flop circuit provides a simple yet effective method for toggling states with a push button while also managing the behavior of an LED indicator, illustrating the interplay between capacitive charging, transistor switching, and load management within electronic circuits.Here are two examples of bistable flip flops which can be toggled between states with a single push button. When the button is pressed, the capacitor connected to the base of the conducting transistor will charge to a slightly higher voltage.

When the button is released, the same capacitor will discharge back to the previous voltage causing the transistor to turn off. The rising voltage at the collector of the transistor that is turning off causes the opposite transistor to turn on and the circuit remains in a stable state until the next time the button is pressed and released.

Note that in the LED circuit, the base current from the conducting transistor flows through the LED that should be off, causing it to illuminate dimly. The base current is around 1 mA and adding a 1K resistor in parallel with the LED will reduce the voltage to about 1 volt which should be low enough to ensure the LED turns completely off.

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