Desde 1994 en la Red. La pagina de los aficionados a la electronica, informatica y otras curiosidades de la vida. No dudes en visitarnos.
Ahora 2 visitas.| 3431969 Visitas (desde Dic. 2011), hoy: 476 Visitas 1108 Pag. Vistas , ultimos 36 dias: 14558 Visitas. 35326 Pag. Vistas. Tu IP:
Que ando curioseando:
AutosuficienciaCosas de casaElectronicaEn InternetInformáticaMundo MisticoSin categoríaSociedadTe lo recomiendo

Luces de bicicleta.

40 LED Bicycle Light

The 555 circuit below is a flashing bicycle light powered with four C,D or AA cells (6 volts). Two sets of 20 LEDs will alternately flash at approximately 4.7 cycles per second using RC values shown (4.7K for R1, 150K for R2 and a 1uF capacitor). Time intervals for the two lamps are about 107 milliseconds (T1, upper LEDs) and 104 milliseconds (T2 lower LEDs). Two transistors are used to provide additional current beyond the 200 mA limit of the 555 timer. A single LED is placed in series with the base of the PNP transistor so that the lower 20 LEDs turn off when the 555 output goes high during the T1 time interval. The high output level of the 555 timer is 1.7 volts less than the supply voltage. Adding the LED increases the forward voltage required for the PNP transistor to about 2.7 volts so that the 1.7 volt difference from supply to the output is insufficient to turn on the transistor. Each LED is supplied with about 20 mA of current for a total of 220 mA. The circuit should work with additional LEDs up to about 40 for each group, or 81 total. The circuit will also work with fewer LEDs so it could be assembled and tested with just 5 LEDs (two groups of two plus one) before adding the others.

Escribe un comentario

Tu comentario