# Clock for leds exercise

**URL:** <https://forum.xod.io/t/clock-for-leds-exercise/919>\
**Category:** Uncategorized\
**Created:** [July 3, 2018, 5:46pm UTC](https://forum.xod.io/t/clock-for-leds-exercise/919 "2018-07-03T17:46:38Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jjusturi](https://avatars.discourse-cdn.com/v4/letter/j/e19b73/32.png) [@jjusturi](https://forum.xod.io/u/jjusturi)\
**Post date:** [July 3, 2018, 5:46pm UTC](https://forum.xod.io/t/clock-for-leds-exercise/919/1 "2018-07-03T17:46:39Z")

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Hello, i have an exercise to flash and turn off some leds in a second, i use a clock node and a led node but doesnt work, what i.m doing wrong?

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**Author:** ![nkrkv](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.xod.io/nkrkv/32/8_2.png) [@nkrkv](https://forum.xod.io/u/nkrkv)\
**Post date:** [July 4, 2018, 8:51am UTC](https://forum.xod.io/t/clock-for-leds-exercise/919/2 "2018-07-04T08:51:17Z")

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Hello!

Have you followed the built-in tutorial? In particular, the [chapter about flip-flop](https://xod.io/docs/tutorial/24-flip-flop). If yes and you’re still having problems, please share a screenshot of your patch here.