LED Dominos Using a 555 Timer - The Learning Circuit

Описание: In the last lesson, we learned what happens inside a 555 timer to make it work. In today’s episode, Karen uses 555 timers to make LED “dominos”. Each unit has an LED connected to the output of a 555 timer and an LDR attached to the trigger. When the LDR senses light, the 555 is triggered turning the light on for a brief period of time. When multiple units are placed in a row, each one triggers the next. The duration that each light is on is determined by an “RC circuit” made of a resistor and capacitor. Changing their values can change the duration that the light is on : http://bit.ly/2rTbKMg


The idea for this project came from a video made by Randy Elwin back in 2011. Karen uses his idea to make a similar device to show off using a 555 timer in a monostable circuit. (Learn more about monostable circuits in the NEXT lesson about 555 timers.) Shining a light on the LDR triggers Pin 2 and the 555 is “set” on. The RC circuit connected to pins 6 & 7 eventually cause the voltage at Pin 6 to go High enough to reset the 555, turning the LED off.
Video Link:    • Le Dominoux  



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