tree sound sensor

ebeowulf17

Joined Aug 12, 2014
3,307
Some piezo elements are true ceramics and won't be much affected by water, those can be bonded to the wood for optimum acoustic coupling.

The electronics aren't difficult to seal against water, or could simply be attached by connectors and taken in when it rains.

In close contact, the sap in the wood would damage any piezo salt based element, the ceramic pellet from the spark generator in a cigarette lighter is probably the highest output and easiest to get hold of - most discount stores near me have packs of 4 lighters for £0.99p.
Very interesting. I don't even need to record a tree, but I'm half tempted to make one of your piezo pickups just to try it out. Sounds fun!
 

ian field

Joined Oct 27, 2012
6,536
Very interesting. I don't even need to record a tree, but I'm half tempted to make one of your piezo pickups just to try it out. Sounds fun!
Experiments with the JFET salvaged from an old electret capsule showed that quite a few types of capacitor were also microphonic.

The first TL431 prototype was built with a very tatty 100uF capacitor found rolling about on the bench - it worked brilliantly.

Subsequent builds had decent capacitors in the AC nfb shunt and were a bit prone to picking up local radio.

The scruffy electrolytic must have had a fair bit of ESR, and probably self inductance, the big difference was the dodgy electro didn't shunt HF nfb so the HF gain tailed off at a sensible frequency, the 'good' electrolytic stopped *ALL* nfb - so the only thing limiting frequency response was the TL431 itself.

Put a resistor in series with the nfb shunt capacitor, try about 100R for starters and experiment from there.
 

GopherT

Joined Nov 23, 2012
8,009
I couldn't believe it when I read it but I'll let you judge for yourself.

Listening to a Tree
Trees are alive! A tree is active long before its leaves sprout in the spring. Sap is circulating in its vessels as the tree prepares to nourish the cells that will produce leaves, branches, and wood.

You didn't realize that a tree has fluid circulating in its vessels? Or that this fluid nourishes cells? Does that remind you of something? That's right! It's just like us humans!

You can hear how various parts of our bodies function with a stethoscope. Well, you can do the same thing (or just about) with a tree!

Early spring is the best time of the year to listen to a tree, when it's practically gurgling with sap. But not all trees are good subjects. Avoid softwoods and pick a hardwood tree. You'll want one at least 15 centimetres in diameter with smooth, thin bark. Birch, beech, and cherry trees are good choices. Place the stethoscope against the trunk of the tree and listen closely. You may need to move the stethoscope around a bit to find a good spot for listening.

Then listen up! You'll hear your tree gurgling, crackling, and bubbling!
From...

https://www.theforestacademy.com/experiments/listening-to-a-tree/#.VbL2YNq9KSM
 

ian field

Joined Oct 27, 2012
6,536
A product idea is forming. MicroDruid™ Sensitive Tree Listener.
The project was published in Elektor magazine a few years ago - I had to sign over copyright before they paid me for it.

Anyone wanting to use it commercially should obtain a copy of the article and make sure their creation differs sufficiently from the original.
 

Thread Starter

Tony Elliott

Joined May 8, 2015
158
Thank you for all your help and suggestions. I have been playing with oscillators relays and diodes, contact mics and have been moving forward with promising results:)
 

wayneh

Joined Sep 9, 2010
17,496
Be sure to come back with results. I'm curious what you'll find. Here in the Midwest we listen to the corn grow this time of year.
 

GopherT

Joined Nov 23, 2012
8,009
The project was published in Elektor magazine a few years ago - I had to sign over copyright before they paid me for it.

Anyone wanting to use it commercially should obtain a copy of the article and make sure their creation differs sufficiently from the original.
I could not find this article. What year/issue is it published?
 

ian field

Joined Oct 27, 2012
6,536
That's the one - some of the filter components may not be needed in every case, R1 & C1 may not be needed or possibly the 100R in series with the 100uF electrolytic. The first ever prototype had a very dodgy 100uF with lots of ESR - that circuit worked perfectly. With a good 100uF you may need the series 100R so you get some AC nfb at higher frequencies. If it doesn't pick up local radio - you can simplify it.
 

AdaHD

Joined Dec 6, 2015
1
Did you finish your project? I'm currently doing a similar project and I'd love to hear about your results! Did you end up using solar panels for power supply? How did you make it waterproof? And how long are you planning on leaving it outside?

Thanks in advance,

Ada
 

ian field

Joined Oct 27, 2012
6,536
Did you finish your project? I'm currently doing a similar project and I'd love to hear about your results! Did you end up using solar panels for power supply? How did you make it waterproof? And how long are you planning on leaving it outside?

Thanks in advance,

Ada
One of the UK magazines did a solar powered weather data logger. Probably EPE magazine.

If you can order photocopies of that article, it would cover most of the salient points.
 

Thread Starter

Tony Elliott

Joined May 8, 2015
158
Did you finish your project? I'm currently doing a similar project and I'd love to hear about your results! Did you end up using solar panels for power supply? How did you make it waterproof? And how long are you planning on leaving it outside?

Thanks in advance,

Ada
We used 12 volt acid lead battery and a solar panel from Maplins with a trickle circuit in-between. We need to test the setup for a longer period to see how effective the solar panels recharge the battery. We made them waterproof by incasing them in clear acrylic glued with epoxy resin (Araldite) and sealant.
 

hp1729

Joined Nov 23, 2015
2,304
Hello,

I am looking to drill a small hole and listen to the activity inside a tree. I am thinking of using a contact mic and clamping it onto a metal insert and then amplifying it, does anyone know of a ideal setup for this kind of tree probe sensor?
What sounds do you expect to find? I suspect you wouldn't get much more than the sound of wind moving branches. Do you limit it to audio range? The sensor must be appropriate to the range of frequencies you are interested in. Sub-audio? Ultrasonic? What kind of amplifier and filter are you using?
 

BR-549

Joined Sep 22, 2013
4,928
So that's what the inside of a tree sounds like. I was expecting something different.

I was hoping for squeaks and slow bubbles.

Maybe a yawn every now and then.
 

hp1729

Joined Nov 23, 2015
2,304
So that's what the inside of a tree sounds like. I was expecting something different.

I was hoping for squeaks and slow bubbles.

Maybe a yawn every now and then.
So what does the tree listener find? We will have to wait and see if he should post his findings.
Maybe a slow oooommmmmm as the tree meditates on the meaning of its life. Maybe the sound of car traffic its roots pick up. Maybe the local radio station "XERB, the big X over Los Angeles. Aaaaoooooowwww!"
Dang, now we need to cover the whole RF spectrum also. :)
I hope no tax dollars are paying for this study. :)
 

hp1729

Joined Nov 23, 2015
2,304
So what does the tree listener find? We will have to wait and see if he should post his findings.
Maybe a slow oooommmmmm as the tree meditates on the meaning of its life. Maybe the sound of car traffic its roots pick up. Maybe the local radio station "XERB, the big X over Los Angeles. Aaaaoooooowwww!"
Dang, now we need to cover the whole RF spectrum also. :)
I hope no tax dollars are paying for this study. :)
After listening to the reported recording ...
How did he distinguish between the sounds of the tree and noise picked up by the wires themselves as an antenna?
 
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