A littleBits puzzle - part 2

Hi all you bitsters out there !
I have a puzzle for you.
How can we make a led turn on for very short times and stay off for longer ? And to make it more fun, we can adjust the time intervals between on and off. And we can only use 5 bits.

3 bits is also possible…

Hi @alexpikkert,
Nice try, but when we would use a micro sequencer, the speed rate would also be affected ( it seems that this shows not clear in the puzzle question, I figured this out now ). :open_mouth:

I meant, through an adjustment, we could change the ratio between on and off state, without altering the speed rate.
A sort of PWM ( pulse width modulation ).
All digital and analogue solutions and ideas are welcome !
Good luck :grinning:


I cannot find a solution… grrr

Well, here’s a hint :
Think of a triangle, the width of the base is wider than the top.
Translated to electronics, if we could only measure this width, we would have a pulse that varies in duration.
And it just happens now that we have the bits needed to measure this :bitstar:
And guess what, they are all analog bits …

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Hi Frank @Frankje,
I think i found a solution with only four bits…

Power-sawtooth oscillator- threshold-rgbled

In this circuit the frequency is set by the oscillator and the pulse width can be varied by changing the setting of the threshold bit. This bit switches ON when the value of the rising sawtooth reaches the set level.
I used my oscilloscope to check the pulses…

See this video:

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You found it :clap::clap:
Indeed, when using a sawtooth wave, we see a slope. The threshold bit looks at this slope and changes state when the voltage is above a certain level.
By adjusting the threshold, we can create shorter or longer intervals.
Great thinking Alex !

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WOW! This is SO COOL @Frankje and @alexpikkert ! @tomparsons2 check out this feed and the other puzzles @Frankje is posting. :slight_smile:

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