How to make a servo run sporadically (violin)


I’ve bought lots of littlebits that I use for a sound-installation. What I’m now wondering is this:

  • I have a power + dimmer + servo config which I use for making a violin play by itself, which works pretty well. But I don’t want the violin to be playing all the time - so I would like it to play a little, then pause a little, play a little then pause a little and so forth…

Anyone know a simple way to do this? I’m thinking that perhaps I could use a timeout-bit? Would I have to combine it with something like a… latch in order to do this in that case?
I don’t want to add anything complicated like arduino-logic or anything like that, the ideal would just be something that turns the power on/off at some kind of interval (like 30 sec / 1 minute intervals, something like that).

Anyway, if somebody have any thoughts on how to achieve this I would be really grateful.


Hi Jonas @hyrfilm,
A violin playing by itself is something special !
I checked my littleBits and found a possible solution with existing standard bits without programming…
I connected the oscillator i31 to the sequencer i22 and connected the time-out i17 to one of the outputs (nr 5) from the sequencer.
The time-out bit triggers my RGB led, I could not try a servo because they are all built inside a new project for Halloween… :smiling_imp:
Maybe this solution is useful for you, after I made it I thought is was a little overdone this way (and not cheap also), but I could not find another timing combination. I hope it will work with a servo, because servos generate a lot of noise in the system… Maybe in future there will be a real clock bit available, as designed by @chris101
The oscillator is set to the lowest possible frequency on square waveform, you must start this bit up by increasing the frequency first and after that setting it on the lowest frequency, else it will not start…
The sequencer is set to forward step.
The time-out bit is set to on-off and a time of appr. 35 seconds.
See this video, ON time is 37 seconds and OFF time is 94 seconds…
Let me know if this was helpful…

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Hi @hyrfilm and @alexpikkert!

I have found that a lot of the current related jitters caused by a servo motor can be alleviated by isolating the servo with a wireless transmitter/receiver pair. That way, the servo operates from a different power supply than does the control circuitry.


Hi, Jonas @hyrfilm ! Can we PLEASE see your itty bitty violin playing?!

In the meantime, I’ll put on my thinking cap for you. :slight_smile:

When will we see your Halloween project, @alexpikkert? :clock1030:

Hi Jude @JackANDJude,
before october 31… WHOOOHHAHAHA…

Hi!! Thanks for the speedy answers and great ideas!

@alexpikkert thanks for your suggestions! Using a sequencer was clever, I think I’ll try that. I’m thinking of having the sequencer run in random mode and trigger it with a pulse bit (which I already own) and then have a latch connected to one of the outs of the sequencer and after the latch have servo. So it would irregularly be turned on / off… Does this sound reasonable?

@chris101 so using a wireless transmitter / receiver would make the start of the servo less jumpy? Is that what you meant?

@JackANDJude sure :slight_smile: here’s short clip I recorded in my studio today, it’s a bit messy at the time though… In this clip I used power + dimmer + pulse + servo + vibration motor. On top of this there are some mics, guitar pedals, bongo drums and the violin:


WOW @hyrfilm! What an exciting work in progress! I’d be tempted to use a sound trigger before the servo to see how irregularly the servo gets triggered by other instruments. :violin: Please do keep us updated! :slight_smile: Can you tell us more about your vision for this project?

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Hi @hyrfilm,
I like your “messy” video, it looks like an automated orchestra beiing born ! Great, it is very creative ! The vibration bit used on the violin is wonderful ! !

Yes it sounds Very reasonable !
I did not use the pulse bit, because its step frequency is faster than the oscillator at lowest frequency, but it it worth a try ofcourse…
Using the latch is also a good idea.
About the servo:
The jumpy start is unavoidable, the initialisation when the power is activated cannot be changed I think. What I ment was the fact that the internal coils of the servo turning the motor work with a strong magnetic field and the little load peaks of the current involved induce fluctuations on the power connection VCC from all the bits connected.
When for example a speaker with the MP3 player is connected in the same circuit, you can clearly hear these fluctuations as a funny but unwanted noise.

If you want to know more about this you can find detailed info in this forum thread, there is a clear video of an oscilloscope screen somewhere where you can see the noise :

As @chris101suggested, separating the load of the servo via the wireless bits is a fine solution, I hope for you that maybe in your orchestra it is no issue at all, please keep on experimenting and please show your progress to all of us. Great ! :violin:

[quote=“hyrfilm, post:6, topic:22794, full:true”]
@chris101 so using a wireless transmitter / receiver would make the start of the servo less jumpy? Is that what you meant?..[/quote]

Yep, that’s exactly what I meant, as well as it isolates the servo from other bits and makes them more reliable as well.

Your ensemble is way cool. I want to hear more!