Feb 262015
 

Flashing lights for pedestrians

This is a simple circuit that uses LEDs that turn on and off continuously. Two groups of high-intensity white LEDs are lit in turn, being easily visible at night. Some people use clothes with phosphorescent colors, in order to be more visible at night and avoid accidents by lack of visibility for drivers of cars. This happens especially on streets with little or no light.

This Flashing lights for pedestrians is suggested in order to further enhance the visibility of pedestrians. This device may be placed in any part of the body such as an arm.

Flashing Lights for Pedestrians

How the Flashing lights for pedestrian works

The circuit consists of two parts:

  • Part One. It consists of an astable multivibrator using two 2-input NAND gates. The two outputs of the NAND gates of this multivibrator apply to other two NAND gates that act as investors gates (NOT gate). The latter gates could not be used, but are used to fill all gates of the integrated circuit.
  • Part Two. Each output is applied to a transistor through a resistor. These transistors constantly move from region to region cutting saturation turning on and off 4 LEDS in groups of two.

The oscillation frequency of the astable multivibrator can be modified by changing the values of resistors R1 and R2 and the electrolytic capacitors C1 and C2.

If you want to increase the intensity of light, change the groups of 2 LEDs in series by groups of 3 LEDs in series, removing resistors R6 and R7. The circuit is powered by a 9 volt battery, easy to carry.

List of circuit components for Flashing lights for pedestrian

  • IC1: 1 4011B IC (four two-input NAND gate).
  • Q1 = Q2: 2N3904 NPN bipolar transistors.
  • D1 = D2 = D3 = D4: High efficiency white LEDs.
  • R1 = R2: 470K, 1/4W resistors.
  • R3 = R4: 47K, 1/4W resistors.
  • R5 = 1K, 1/4W resistor.
  • R5 = R6: 330, 1/4W resistors.
  • C1 = C2: 4.7uF / 25V or more electrolytic capacitors.
  • SW1: switch.
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