Hello all,
I am trying to create a flashing 3 LED circuit with a 9v battery. I want a specific flash time of 20ms and a duty cycle of 1.3 seconds. My question is what size should R1, R2, and C1 be in order to achieve that timing. I found the equations for figuring it out, I was hoping maybe someone would rather take the challenge of giving me the answer instead of me going back to school to relearn algebra. Any help is very much appreciated.
Thanks.
Hi Rob, Just for the fun of it I mocked up your idea using an Arduino Duemilanove. I will attach a video but keep in mind that my camera has a slow scan rate and as such it misses the 20 uS flash occasionally. In real life the 3 LEDs flash for 20 uS and then are off for 1.3 seconds before they flash again. The camera misses every third of fourth flash. I have taken the simplest of Arduino sketches called "Blink" and modified it to your specifications of 20 uS on and 1.3 Seconds off. The Arduino outputs this signal on pin 12 in this case and I am using the signal to trigger an NTD4906 gate level N channel MOSFET. I am supplying 9 volts to the LEDs and the FET so there is enough voltage to drive them in series and there is also a 220 ohm current limiting resistor in series. I do not know the intention of your project whether you need this effect or if you are just trying to learn about the 555.
John
Hi Rob, Just for the fun of it I mocked up your idea using an Arduino Duemilanove. I will attach a video but keep in mind that my camera has a slow scan rate and as such it misses the 20 uS flash occasionally. In real life the 3 LEDs flash for 20 uS and then are off for 1.3 seconds before they flash again. The camera misses every third of fourth flash. I have taken the simplest of Arduino sketches called "Blink" and modified it to your specifications of 20 uS on and 1.3 Seconds off. The Arduino outputs this signal on pin 12 in this case and I am using the signal to trigger an NTD4906 gate level N channel MOSFET. I am supplying 9 volts to the LEDs and the FET so there is enough voltage to drive them in series and there is also a 220 ohm current limiting resistor in series. I do not know the intention of your project whether you need this effect or if you are just trying to learn about the 555.
John
