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This LED series will blink alternately. The operation is determined by the NE555 integrated circuit, with transistors used to reinforce each section (20 upper, 20 lower) for optimal performance. The 555 circuit described below functions as a flashing bicycle light powered by four C, D, or AA cells (6 volts). Two sets of 20 LEDs will flash alternately at approximately 4.7 cycles per second using the specified RC values (4.7K for R1, 150K for R2, and a 1µF capacitor). The time intervals for the two lights are about 107 milliseconds (T1, LED on) and 104 milliseconds (T2, lower LEDs). Two transistors are utilized to provide additional current beyond the 200mA limit from the NE555 timer. A single LED is connected in series with the PNP transistor base, ensuring that the 20 LEDs are turned off when the output is high during the T1 time interval. The high-level output of the NE555 timer is 1.7 volts lower than the supply voltage. Considering the forward voltage drop of the LED, the required activation voltage for the PNP transistor increases to approximately 2.7 volts, meaning the 1.7 volts difference from the supply to the output is insufficient to turn on the transistor.
The described circuit utilizes the NE555 timer in astable mode to generate a square wave output, which is responsible for the blinking effect of the LEDs. The timer operates by charging and discharging the timing capacitor (1µF) through the resistors R1 (4.7K) and R2 (150K), establishing the frequency of the LED blinking. The calculated frequency of approximately 4.7 Hz results in the specified on and off durations for the upper and lower sets of LEDs.
The two transistors act as switches that manage the current flow to the LED arrays, allowing for a higher current capacity than the NE555 alone can provide. This configuration ensures that the combined current draw of the 40 LEDs does not exceed the output current limits of the NE555, enhancing the reliability and brightness of the light output.
The design includes a protective LED in series with the base of the PNP transistor to ensure that the transistor remains off during the high output state of the NE555 timer. This prevents any unintended illumination of the LED array during the T1 interval. The forward voltage drop of the LED must be accounted for, as it affects the base-emitter voltage required to activate the PNP transistor.
The circuit is powered by a battery pack consisting of four cells, providing a total of 6 volts. This voltage is sufficient to drive the LEDs while maintaining the operational parameters of the NE555 timer and the associated transistors. The overall design is suitable for applications such as bicycle lights, where a visible blinking effect is desired for safety and visibility.
In summary, the described blinking LED circuit effectively combines the NE555 timer with transistor switching to create an efficient and visually effective lighting solution, suitable for various applications.This led series will Blinking alternately, The way it works is determined by IC NE555 and transistors are used as reinforcement for each section (20 upper, 20 lower) work optimally. 555 circuit below is a flashing bicycle light powered with four C, D or AA cells (6 volts). Two sets of 20 LEDs will flash alternately at about 4. 7 cycles per second u sing RC values shown (4. 7K for R1, 150K for R2 and 1uF capacitor). Time intervals for two lights about 107 milliseconds (T1, LED on) and 104 milliseconds (T2 lower LEDs). Two transistors are used to provide additional time beyond the current limit of 200mA from the NE555 timer.
A single LED is placed in series with the PNP transistor base so that the 20 LED 555 is turned off when the output is high during a time interval T1. High-level output timer 555 is 1. 7 volts less than the supply voltage. Adding the LED forward voltage increase is required for the PNP transistor to about 2. 7 volts, so the 1. 7 volt difference from the supply to the output is not sufficient to activate the transistor. You are reading the article about Blinking LED circuits and you can find articles Blinking LED circuits this the url.
You may distribute or copy articles Blinking LED circuits this is beneficial if you or your friends, but do not forget to include the link source. 🔗 External reference
The described circuit utilizes the NE555 timer in astable mode to generate a square wave output, which is responsible for the blinking effect of the LEDs. The timer operates by charging and discharging the timing capacitor (1µF) through the resistors R1 (4.7K) and R2 (150K), establishing the frequency of the LED blinking. The calculated frequency of approximately 4.7 Hz results in the specified on and off durations for the upper and lower sets of LEDs.
The two transistors act as switches that manage the current flow to the LED arrays, allowing for a higher current capacity than the NE555 alone can provide. This configuration ensures that the combined current draw of the 40 LEDs does not exceed the output current limits of the NE555, enhancing the reliability and brightness of the light output.
The design includes a protective LED in series with the base of the PNP transistor to ensure that the transistor remains off during the high output state of the NE555 timer. This prevents any unintended illumination of the LED array during the T1 interval. The forward voltage drop of the LED must be accounted for, as it affects the base-emitter voltage required to activate the PNP transistor.
The circuit is powered by a battery pack consisting of four cells, providing a total of 6 volts. This voltage is sufficient to drive the LEDs while maintaining the operational parameters of the NE555 timer and the associated transistors. The overall design is suitable for applications such as bicycle lights, where a visible blinking effect is desired for safety and visibility.
In summary, the described blinking LED circuit effectively combines the NE555 timer with transistor switching to create an efficient and visually effective lighting solution, suitable for various applications.This led series will Blinking alternately, The way it works is determined by IC NE555 and transistors are used as reinforcement for each section (20 upper, 20 lower) work optimally. 555 circuit below is a flashing bicycle light powered with four C, D or AA cells (6 volts). Two sets of 20 LEDs will flash alternately at about 4. 7 cycles per second u sing RC values shown (4. 7K for R1, 150K for R2 and 1uF capacitor). Time intervals for two lights about 107 milliseconds (T1, LED on) and 104 milliseconds (T2 lower LEDs). Two transistors are used to provide additional time beyond the current limit of 200mA from the NE555 timer.
A single LED is placed in series with the PNP transistor base so that the 20 LED 555 is turned off when the output is high during a time interval T1. High-level output timer 555 is 1. 7 volts less than the supply voltage. Adding the LED forward voltage increase is required for the PNP transistor to about 2. 7 volts, so the 1. 7 volt difference from the supply to the output is not sufficient to activate the transistor. You are reading the article about Blinking LED circuits and you can find articles Blinking LED circuits this the url.
You may distribute or copy articles Blinking LED circuits this is beneficial if you or your friends, but do not forget to include the link source. 🔗 External reference