How do I calculate which resistor I need to make LEDs blink once every 2 secs? - what can you make with leds
Currently I have entails a 4000mcd LED 3V (two batteries type C) and resistance of 100 ohms is completed and the light, I seek.
I would like a capacitor to the LED blinks slowly to use (every 2 seconds) and continuous. How do I calculate the capacitor do I need?
Friday, February 12, 2010
What Can You Make With Leds How Do I Calculate Which Resistor I Need To Make LEDs Blink Once Every 2 Secs?
Subscribe to:
Post Comments (Atom)
3 comments:
For those who think it does not work, I think it could. For an exact calculation, which we really need, the IV curve for the LED, but often have a silicon diode of 0.6 V over them to the behavior. Then put the capacitor on the LED (Case of 300 ohms in series) at the beginning. Connect the negative terminal of the battery to the LED and the other nodes of the parallel combination with another resistor to the positive terminal of the battery. A very rough approximation can, by the circuit RC time constant be equal to 2s. Thus, a resistor 20 000 ohms, with a capacity of 100 microfarads. That tolerance of electrolytic capacitors is generally 100% -25% in May of this approach enough. I suggest you use anPreset resistance / potentiometer.
The operation is that the capacitor is charged by the opposition and when the voltage across the LED reaches 0.6 V led to capacitor discharge, as the resistance of the LED decreases the tension is rising.
Let us try to improve a little in this calculation. The capacitor voltage rises to the equation:
V = V0 (1 - exp (-t / T))
Now t is about 1 s, half the time when the capacitor is to be charged and discharged. As the battery 3V, V/V0 about 2
Then .2 = 1 - exp (-1 / T)
Dar exp (-1 / T) = .8
O 1 / T =- ln.8 => T = -1/ln.8 = 4.5
This results in an RC time constant of 4.5 slightly higher than the value of 1 ABOVE. Thus, C of 470 microfarads, R 10 000 ohms (with the values of the preference shares).
As I said, it could work. You have to adapt, to use an adjustable resistance.
Sorry, will not work. Not even blink only one capacitor, if you have a mass. You need to be more complicated.
Could do the neon age, because ionized and has become a short circuit, the cycle begins anew. But LEDs.
You can buy the flash, however.
You need an oscillator circuit for flashing the LED. Only the capacitor and the resistance is not enough. For the most lines from the time at T = 0.7 * R * C So if you are given a period of 2, you must choose R * C = 2.8s. Please note that research is not a 100-ohm resistor, but the resistance is used in the oscillator circuit. Suppose you are using 100kohm a resistance, then C = 2.8s/100kOhm = 28uF. You can use either one or a capacitor 27UF 33UF.
If you Google "light is flashing circuit to find many suggestions as we build this circuit.
Post a Comment