Mysterious i13 light sensor bit

Who could explain the mysterious working of the i13 light sensor?
I am wondering what the purpose of the light sensor input is…
In all ( I think) Littlebits examples and tips and trics the light sensor is always connected to a power bit, so the input is set on VCC 5 Volt level.
But the sensor also works without anything connected to the input side (I found this out while working on a project where the sensor is connected to an input from the W6 Arduino)
I really wonder what the purpose of the light sensor input could be…:open_mouth:



Hi @alexpikkert
If I’m not mistaken when I see the schematic, the input controls the depth of the sensing level of the phototransistor. The input opamp part is a non inverting buffer… the transistors afther that set the min and max level depending of the input… so you could say that the input sets a window where the light sensitivity resides.
Must check this out this evening.

Hi all,
I made a circuit using a dimmer at the input of the light sensor and a number bit at its output.
With the same amount of light, striking the light sensor, and varying the input with the dimmer bit, I’ve noticed that we can narrowing or widening the min and max output.
What about chaining 2 light sensor bits ?
By the way, have you also noticed that the microphone bit i21 has an input ?
The schematic reveals that this input controls the volume of the microphone or mini jack …
So, this module could also be used as a VCA ( Voltage Controlled Amplifier ) for the synth kit.
LittleBits has truly an infinite way of usages :grinning:


Thanks @Frankje for this explanation !
At this moment I cannot test my light sensor, it is built inside a project I am working on… :joy_cat:
But I tried the microphone bit as you mentioned, and it works, I changed the volume of the input with the oscillator bit, first with a sawtooth signal an then with the square signal.
See this video:


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Heheh, next time I will keep my secrets for myself :joy::joy:
I was working on a VCA bit lately and noticed that the microphone bit could be used as a VCA, thanks to its input.
And I have more fresh ideas about using the littleBits modules for other purposes as intended, keep tuned as they will be published here.

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