MicroPython Forum (Archive)

Hi, I want to design a game with my boy. I want to setup a LED as the light of a candle. And when blowing to the candle, the light turns off.

Please advise which sensor I can use to capture the action of blowing in the air. Thanks.

Temperature sensitive components like ntc or ptc resistors or Humidity sensors. The changes can be rather small.

How about a photo sensor near the LED with a pivoted or hanging shutter which normally blocks the light. Blowing temporarily moves the shutter exposing the sensor. Arguably more educational as its operation is visible.

A similar thing could be done with a hanging magnet and a hall effect sensor or reed switch.

In the analog days I saw a nice demo with an LED lighting a photocell. They were wired in a simple positive feedback loop. You lit the LED with a match, and snuffed it out with your fingers...

Thanks for advises. i will try.

Maybe try to use Ultra Low Pressure Sensor.

I like the idea of photosensor + LED. Cold be a forked light sensor. That sounds responsive and easy to implement

I think I remember a project of a blowable electronic candle that used the LED itself as the sensor, measuring the changes in its resistance due to temperature changes.

If you want to be more accurate and sensitive, for example for electronic woodwind instruments, there are pressure sensors that can handle this.

deshipu wrote: ↑

Fri Sep 11, 2020 1:03 pm

I think I remember a project of a blowable electronic candle that used the LED itself as the sensor, measuring the changes in its resistance due to temperature changes...

Interesting - but I guess the changes would be quite small. As Robert suggested, a PTC thermistor could be used. I'd wire it such that it runs hot, say 60°C. The change in resistance would then be more substantial.

Found it: https://hackaday.com/2018/08/21/an-led- ... ed-sensor/

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