Hi,
I am trying to build a watertight housing that should be put into water.
I am trying to figure out how mobile phones makes sure not to short curcuit anything when they are put into water. My current phone can still work if it is dropped into water, but it has an open usb connector. Do they have some sense curcuitry that senses if there is a short and then disconnects the signals or is there some smart connectors that does it automatically?

Thanks for your help,
Morten

 

Put it in a sealed plastic box, designed for underwater IP68 rated.

 

Put it in a sealed plastic box, designed for underwater IP68 rated.

That will unfortunately not work. I am making a new kind of touchscreen which works under water, so I can't seal inside a plastic box.

 

So what exactly do you need? Is it a gland that can pass electrical wires into the body of the thing, or do you really need something that can be connected and disconnected under water? Or connected above water but be water tight?

 

Hi,
I am trying to build a watertight housing that should be put into water.
I am trying to figure out how mobile phones makes sure not to short curcuit anything when they are put into water. My current phone can still work if it is dropped into water, but it has an open usb connector. Do they have some sense curcuitry that senses if there is a short and then disconnects the signals or is there some smart connectors that does it automatically?

Thanks for your help,
Morten

The battery inside a mobile phone is protected with a diode on charge..

And current limiting transistor on discharge...

Additionally, newer phones have a pressure sensor on board and likely trip the current limiting as soon as the phone senses a rapid pressure change (becomes submerged). So "water resistance" is a combination of physical design, sensors and software.

Finally, the conductivity of fresh water is ve low.

 

Water-resistant vs Water-repellent vs Waterproof: What’s the Difference?

First of all, let’s start with some quick definitions of all three terms, as given by the Oxford English Dictionary:

• Water-resistant: able to resist the penetration of water to some degree but not entirely
• Water-repellent: not easily penetrated by water, especially as a result of being treated for such a purpose with a surface coating
• Waterproof: impervious to water

1. Water-resistant, this is the lowest level of water protection of the three. If a device is labeled as water-resistant it means that the device itself may be built in such a way that it is more difficult for water to get inside of it, or possibly that it is coated with a very light substance that helps improve the device’s chances of surviving an encounter with water. Water-resistant is something you see commonly among watches, giving it the power to withstand the average hand-washing or light rain shower.

2. Water-repellent, which is basically just a step up from water-resistant. If a device is labeled as water-repellent it actually possesses the properties in which to, you guessed it, repel water from it, making it hydrophobic. A water-repellent device stands a very high chance of being coated with some form of thin-film nanotechnology, whether that is on the inside, outside, or both, and has a much better chance of standing up to water than your average device. Many companies claim water-repellency, but the term is heavily debated because of all the questions and unpredictable elements associated with it.

3. Waterproof. Although the definition is pretty straightforward, the concept behind it is not. Currently, there is no established industry standard in order for a device to classify as waterproof. The closest thing currently available, as far as a rating scale is concerned, is the Ingress Protection Rating scale (or IP Code). This scale assigns items a rating from 0-8 in terms of how effective the device is at keeping water from entering into it. Obviously, there is one major flaw in this rating system: What about companies, like us here at HZO who are not concerned about keeping water out of a device in order to save it from water damage? These companies provide a service that isn’t compatible with what the IP scale measures, but still manage to provide a solution for those customers that want protection against the dreaded “death by toilet.”

Based on your initial post:

I am trying to build a watertight housing that should be put into water.

You are looking at waterproof by definition. Then it becomes a matter of water proof to what depth? There are waterproof enclosures and waterproof connectors rated to various depths using various designs. They generally have NEMA and Mil-Spec ratings or other ratings as to their construction. Just as an example a box like this could be modified and a touch panel placed in a cutout using a sealant around the edges. The tops of boxes like this normally have a rubber gasket placed in a milled or molded slot.

So it really comes down to size and depth you plan to use the product at.

Ron

 

Evaluate if any of these match your needs...

----> http://www.molex.com/molex/products...itle=Introduction&parentKey=sealed_connectors

----> https://www.amazon.com/M14-3-Waterproof-Connector-Cable-Socket/dp/B00QFAL616

----> https://www.aliexpress.com/item/10-...t-plug-with-2-15cm-cable-for/32250336945.html

----> http://www.diveandsee.com/products/underwater-connectors/DNC-2014

----> http://www.nautikaris.com/product/birns-aquamate-underwater-connector/

 

That will unfortunately not work. I am making a new kind of touchscreen which works under water, so I can't seal inside a plastic box.

Won't the water touch all of the touch screen all of the time?

 

Epoxy seals around all the pins where they exit the connector shell and elastomer seals around the connector/enclosure interface..

http://www.te.com/usa-en/videos/consumer/waterproof-micro-usb.html
etc....

 

So what exactly do you need? Is it a gland that can pass electrical wires into the body of the thing, or do you really need something that can be connected and disconnected under water? Or connected above water but be water tight?

I think I have been unclear in my post. It is not so much how to make the connector sealed. It is more a question about what circuitry is needed to protect the pins, so it doesn't short curcuit the USB connector.

 

So, is the connector a usb device or host? do you use usb otg?

 

I think I have been unclear in my post. It is not so much how to make the connector sealed. It is more a question about what circuitry is needed to protect the pins, so it doesn't short curcuit the USB connector.

I don't see any need to modify the circuitry. USB 2 you only have 4 lines, 5 Volt . DATA +, DATA - and Ground. You would use a waterproof USB connector designed for the application. A Google of "USB Waterproof Connector" will yield plenty of results. Here are a few dozen results. There is no need to modify the circuit, you use a water tight bulkhead connector designed for your application.

Ron

 

I don't see any need to modify the circuitry. USB 2 you only have 4 lines, 5 Volt . DATA +, DATA - and Ground. You would use a waterproof USB connector designed for the application. A Google of "USB Waterproof Connector" will yield plenty of results. Here are a few dozen results. There is no need to modify the circuit, you use a water tight bulkhead connector designed for your application.

Ron

If the thing is a usb host or otg, then I see problems with electrolysis across the pins and rapid discharge of battery.

 

If the thing is a usb host or otg, then I see problems with electrolysis across the pins and rapid discharge of battery.

I agree but if a watertight connector, designed for an underwater application is used I guess I do not see a need to modify or change whatever the circuitry is? Maybe I am missing something? I see a circuit in a water tight enclosure which has a USB connector going to the outside world. There is no mention of the USB connector type? So what could be done to modify the actual circuitry? There is no mention of depth or pressure. There is no mention of salt or fresh water. So what circuit modifications could be done?

As to using a cell phone as an example? My phone, a Samsung Galaxy 7 has a gasket and the micro USB has a gasket. Guessing it would start to leak if the water was deep enough but there is no circuitry built into the phone to prevent water damage that I am aware of. There is also the small headphone jack? I guess they meet IP68 requirements. My guess is use an enclosure and bulkhead connections which meet or exceed IP67 or IP68 requirements. If the depth is known then include a pressure sensitive switch to shut whatever you have down when the pressure exceeds atmosphere pressure.

Ron

 

On my phone that is IP68 rated the usb connector is naked and can be full of water, but the phone doesn´t produce any voltage on that conector as it is a usb device only AFAIK. If it was usb otg, then you could turn the power on periodically and check for a device on the other end.

 

On my phone that is IP68 rated the usb connector is naked and can be full of water, but the phone doesn´t produce any voltage on that conector as it is a usb device only AFAIK. If it was usb otg, then you could turn the power on periodically and check for a device on the other end.

The only time there is voltage on my phones connector is during charge. The original poster does not mention how the connector will be used? Just as an example right now I have an Arduino Uno connected to the PC and on the Uno is a Ethernet shield with a SD card. I guess if for some reason I wanted to place my circuit, the Arduino Uno in a water tight enclosure I would need a watertight USB connector on the bulkhead of my enclosure. In this case my electronics would rely on power through the USB connector. Less knowing exactly what the original poster has in mind it is difficult to provide a concise solution. Beats me?

As to:
How to make a waterproof connector?
I would just buy one rather than make one.

Ron .