Electrostatic Discharge/ ESD troubles with Wool + Arduino Unos + Ultrasonic Sensors

what path does the power to the Music Maker board take?

1 Like

Can you please post a circuit of your setup for one Arduino, and supply a link to your ultrasonic sensor.
What impedance speakers do you use? A note on the schematic says that having speakers greater than 4R dramatically increases the thermal performance. That means it will not get so hot.

When you switch it on first thing in the morning how long does it work for before you get it start to fail?

You seem to have a lot of regulators generating heat in your system.

Yes it is an adaptor. You can get them with a USB end for charging devices so you can power it that way. Or you can get them with an end that looks like the barrel jack of your current adaptor but you then have to use a barrel socket to plug them into and from there you connect it to the Arduino's 5V and ground pin.
Like this one
https://www.micromark.com/Jack-Screw-Term-2-1Mm-5
You could even power multiple Arduinos from the same adaptor by running wires from an adaptor like this. Power adaptors of 3A capacity are not uncommon.

However, even using that might not save you, it depends on the exact amount of heat the rest of the circuit generates and the thermal path from your circuit to ambient.

A thermal path is characterised by what is known as a thermal resistance, it is measured in Degrees Centigrade rise per Watt.

If one end of your thermal resistance is at the ambient temperature the other end gets hotter, the temperature it get to is dependent on the power dissipated and the thermal resistance. The whole thing about wool is that it it is an insulator, that is what the sheep evolved it to be. You felting it added extra pockets of air which makes it an even better insulator. Insulators have a high thermal resistance. There is little point putting a heat sink on the device because in order to dissipate any heat, a heat sink needs an ambient temperature air flow round it.

When the regulators used on the Arduino get past a certain temperature they shut down, that is they stop working.

One way round this might be to use a heat pipe, this sounds fancy but all it is a strip of metal from the heat source to outside the sculpture. This needs to be electrically isolated. Another way to stop it overheating is to use circulating water in a copper pipe visiting all the Arduinos in your system.

1 Like

The Music maker takes its power from the 5V pin of the Arduino! so all that is passed by the on board regulator.

1 Like

Hey Grumpy Mike
Sorry I was unable to reply again last night!

Here is a schematic (its likely using incorrect symbols, sorry about that) and a photo (the usb cord in the photo is not in use). The Speaker is 4 ohm, and I will be using a second speaker in some of them (and could use a second speaker in all of them if it helps use the excess power)

Here is a link to the sensor: Ultrasonic Distance Sensor - HC-SR04 - SEN-15569 - SparkFun Electronics

It is not the use of incorrect symbols it is the total lack of any labelling on the connections which makes it of little use.
I am assuming that the single unlabelled box is in fact two boxes, an Arduino Uno and a sound shield. So a diagram should show two boxes.
Still with all the words I guess we are about there knowing what you have.

As I said the shield will generate much less heat with a higher resistance speaker.

Thanks for the link on the sensor. The current looks small.

The powering of this all with a 9V input to the barrel jack, is just so wrong.
Did you ever stop to feel the on board regulator to see how hot it got?

Get a DVM (digital volt meter) and run a 5V and ground wire from the Arduino. This should measure 5V. Now run it in the woolly jacket and confirm that the voltage drops as the system stops working properly. Make sure you do not short these two wires together or you will need to but another Arduino, or fix the powering sachem like I said before.

One thought I just had, is that the Arduino and sound shield could be located outside the sculpture, say underneath it and run the wires inside just to the speakers and sensors?

Thanks Mike. I will check the regulator, and do your DVM suggestion. About the electronics- we really want them hidden inside the sculptures, but I could get conductive fabric, suspend the Arduino+Shield in a type of faraday cage inside the sculpture, where it would be at least a foot away from any fabric in any direction. But the sensor and speakers would still be touching the wool.

@JohnRob the 5v pin on the Arduino.

Hi, @earliest
A good start to your schematic. :+1:

As @Grumpy_Mike has pointed out some labeling of components and pins are needed.

However a good start as your circuit is relatively well layed out and uncluttered with room to add the labelling.

Tom... :grinning: :coffee: :australia: :+1:

1 Like

@TomGeorge clearly I need to learn how to write a proper schematic :wink:
In the meantime, I hope this is an improvement:

Well, it shows the 9V going into the MP3 shield, which it doesn't, and the sensor also connected to the MP3 shield instead of the Arduino.

So you are still perusing the "its static" line of thinking after all I said.

One of our members @Paul_B has strong opinions about powering things through the on board regulator, let's see if this summons him.

The Faraday Cage concept is much misunderstood in the electronics hobby world. They are not the magic cure all many think them to be.

1 Like

What? You expect me to trowel through 32 posts and research the Audio Shield he is using (I'm not a fan of shields,) and check out the awfully drafted and barely legible schematic for it?

Grumble, grumble. :grimacing:

Nothing on the shield refers to 9 V, only 5 V, 3.3 V and 1.8 V. It draws some 40 to 60 mA so it might be OK on 9 V to the Arduino "Vin" if the SD card and ultrasonic sensors do not draw significant current.

However, as the rather interesting AP7312 regulator is LDO, a 4.5 V battery supplying the "5V" pin would make far more sense. Three alkaline "AA" should last quite a few hours.

1 Like

Hey Mike. There is a lot of space around the Arduino (within the woolen sculptures), pictured. They will be suspended, so at least a foot away from any material (other than the plastic soap box I put them in) in any direction.


Have you tried them not in the plastic box or at least put some holes in the box to get some air flow?

I apologize for the awful schematic she made. I have never done this before.

As for the battery, it will be installed in a gallery for months (without supervision after the first couple weeks), so I am aiming to design it all so that 12 sculptures (+12 arduinos) can be turned on via the track lighting with one light switch. I am gathering from this thread that this may be a mistake.

Thanks for your thoughts

So far these are the only holes I have, I haven't tried it without the box yet.


As it happens, I was not referring to your schematic, but the one on the Adafruit site. :rofl:

Whatever software they used to create it - and it is a fairly common one - made a very bad job of it. Viz.:


Seriously, is that in any way legible? (Click on it, zoom it, etc.)

1 Like