how to make three light bulb blink?

Answer 1

The same way you make one light bulb blink, you just need to consider the total current.

Or do you mean the three should blink one-after-another.

Need more info on what you want to achieve, what power source you have available, what kind of bulbs (voltage, wattage).....etc...

Answer 2

You could program a Programmable Logic Controller with one timer, one counter, three comparators, and three discrete outputs. At startup the counter is reset. Each time interval that a free running timer hits one second, it adds one to the counter. If the counter accumulator equals one the logic turns on the first lamp and turns off the second and third. If the counter accumulator equals two the logic turns on the second lamp and turns off the first and second. If the counter accumulator equals three the logic turns on the third lamp and turns off the first and third. If the counter is greater than three it is reset with a one shot and a one is written to its accumulator.

Answer 3

You could use a relay, programmable timer, programmable logic controller, or even a varible frequency driver.