Implementing a system based in Android + IOIO + relay problem + connector

[annlee]

Hi there, I am doing a system based on Android + IOIO board + Relay for a 230V/16A connector (I am European)

IOIO board only gives 3.3V output (not 5V), so I need a 3.3V relay that works for a 230V/16A connector, is there any relay with this specs?

or

should I need a MOSFET transistor between the IOIO board and the relay? which one?

Thanks in advance

 

[grantr37]

with modification and more expensive components (some surface mount SMD Device etc) this circuit could be designed to run entirely on battery power or even the small 5v 100mA rail provided by the USB device, although this would eat the batteries more quickly.......if you are looking for it to turn on and off an appliance for example without the Android device being plugged into a mains adapter and operating on internal batteries only....or you could even separate the device from the Android minicomputer using a Bluetooth module either internal or one of those tiny little low profile Bluetooth tranceivers that come with a wireless optical mouse plugged into the USB port (again a bit more expensive) but for USB alone it can be done really cheaply...

the separated Bluetooth receiver unit if used could be powered by an internal rechargeable battery and that could in turn be charged by using an inductive coil based charging circuit taking energy from the outer part of the supply cable without any physical connection...so it could be clipped onto the supply cable next to the appliance....as a plug adapter for instance...

 

[grantr37]

what device are you running the Google OS on? so I can know what hardware you would like to use, if it is for all Google Android OS hardware in general this is still easily done....

 

[annlee]

This is a general purpose solid-state relay that is used in pretty much the same way as a traditional relay, but has the advantages of no moving parts, longer life, and wider input voltage range. It gives good isolation figures. Here is a link to it on Farnell's website: PF240D25 - CRYDOM - SSR, 240VAC | Farnell United Kingdom. Double-check the spec, but it looks like it would do what you want. There are probably cheaper ones available - this was the first one I found. Daz

Thanks everyone, the system is meant to work buried (no fan required then + protection against water/dirt) 24/7/365 so batteries is not possible.

uhmmm even when I am not an expert, seems this device could work with the hardware as follows:

From 230v/16A cable = IOIO DC source (5V-15V) + (Android device <-USB-> IOIO board with 3.3V output) + PF240D25 relay + 230v/16A connector cable -> bulb



preferly max 15V source to feed IOIO?

I've found in Orange an "HTC Wildfire S" for 109 Eur, IOIO forums said this model works like a charm

grantr37, you seem to be all-an-expert so get ready if I log in again with newbie issues

 

[grantr37]

There are a few problems that may be encountered, the unit would need to be completely encapsulated in a resinous plastic, which during the factory curing/setting process would generate enough heat (Exothermal) to lift the surface mount components on the I/O card, in addition to this there would always be heat generated by the Integrated circuit chips on board that would become trapped and take extended periods to dissipate.....bonding a high efficiency heatsink would not work very well due to the fact that free air would not be available to allow for removal by convection, you would be relying on soil thermal coefficient, and any bonded metal heatsink would be subject to soil chemistry(corrosion)...
The thermal characteristics of the soil would also vary according to the weather and moisture content and components such as Resistors and capacitors (including non-electrolytic capacitor types such as coltan/tantalum) would be prone to failure in terms of both the physical characteristics altering with temperature differences and by permanent physical breakdown leading to loss of function..
I can't see any reason for burying a perfectly good mini computer device to control only one light fitting, it seems like an economically unproductive approach if this is for a business product?

which company do you work for?

 

[annlee]

There are a few problems that may be encountered, the unit would need to be completely encapsulated in a resinous plastic, which during the factory curing/setting process would generate enough heat (Exothermal) to lift the surface mount components on the I/O card, in addition to this there would always be heat generated by the Integrated circuit chips on board that would become trapped and take extended periods to dissipate.....bonding a high efficiency heatsink would not work very well due to the fact that free air would not be available to allow for removal by convection, you would be relying on soil thermal coefficient, and any bonded metal heatsink would be subject to soil chemistry(corrosion)...
The thermal characteristics of the soil would also vary according to the weather and moisture content and components such as Resistors and capacitors (including non-electrolytic capacitor types such as coltan/tantalum) would be prone to failure in terms of both the physical characteristics altering with temperature differences and by permanent physical breakdown leading to loss of function..
I can't see any reason for burying a perfectly good mini computer device to control only one light fitting, it seems like an economically unproductive approach if this is for a business product?

which company do you work for?

Great reply! I considered the heat problems but not so so... because its buried, but I think you are right
Since this system can work I am happy for now! the problem about heat, water, dirt... should be studied by a friend of mine, Mechanic Engineer and Expert in CAD to design the protective cover. Perhaps a 3V fan and/or even sinking in olive oil could refrigerate it properly

This system would be part of my PhD

 

[grantr37]

with a fan in a unit that would be by design intent covered in soil, this would serve no meaningful purpose, there is no free air for convection through expansion or available air for throughpass, the fan would also be subject to immediate mechanical stoppage and failure.
In addition encapsulation in any kind of oil would result in issues involving sealed (limited) thermal expansion which could result in possible rupture or strata charging, leading to chemical interaction with printed circuit tracks and components, the tracks could be lifted by warm oil or corroded by the nature of the oil chemistry, either of the two could lead to broken circuit board tracks and an open circuit, internal characteristic breakdown of the individual components could also occur, even when using mineral and synthetic oils blended for dielectric stability, this also applies to signal crosstalk where the liquid oil conducts between tracks and components, this can also cause issue with logic switching and signal debouncing...

 

[annlee]

with a fan in a unit that would be by design intent covered in soil, this would serve no meaningful purpose, there is no free air for convection through expansion or available air for throughpass, the fan would also be subject to immediate mechanical stoppage and failure.
In addition encapsulation in any kind of oil would result in issues involving sealed (limited) thermal expansion which could result in possible rupture or strata charging, leading to chemical interaction with printed circuit tracks and components, the tracks could be lifted by warm oil or corroded by the nature of the oil chemistry, either of the two could lead to broken circuit board tracks and an open circuit, internal characteristic breakdown of the individual components could also occur, even when using mineral and synthetic oils blended for dielectric stability, this also applies to signal crosstalk where the liquid oil conducts between tracks and components, this can also cause issue with logic switching and signal debouncing...

certainly, the heat is a big issue even when its buried, I think I do have to learn/read a lot yet

I was thinking about a ceramic-based jug cover around the sealed electronic devices + external metalic with a lock

This is how works the ceramic jug to refrigerate: Google Translate :blush2:

 

[DPG]

How warm is this thing going to get? Will the temperature exceed the maximum operating temperature of the components - you would probably be surprised how hot modern components can run at safely. Are liquid cooling and forced air cooling necessary? Daz

 

[annlee]

How warm is this thing going to get? Will the temperature exceed the maximum operating temperature of the components - you would probably be surprised how hot modern components can run at safely. Are liquid cooling and forced air cooling necessary? Daz

Good questions but I cant tell until I start the project :stuart:

 

[grantr37]

How warm is this thing going to get? Will the temperature exceed the maximum operating temperature of the components - you would probably be surprised how hot modern components can run at safely. Are liquid cooling and forced air cooling necessary? Daz

microcomputer hardware does not have a very good tolerance for heat, there are a few that are designed for low power operation and low thermal output, such as the Intel Atom processor, and a few ARM modules, other than that its down to RISC microprocessors ....

with overheating, it is a choice of continuous set-reset shutdown sequences or thermal runaway and burning out....

 

[annlee]

microcomputer hardware does not have a very good tolerance for heat, there are a few that are designed for low power operation and low thermal output, such as the Intel Atom processor, and a few ARM modules, other than that its down to RISC microprocessors ....

with overheating, it is a choice of continuous set-reset shutdown sequences or thermal runaway and burning out....

Hi there buddies, I asked Crydom about the PF240D25 relay heating specs and this is what they said:

Good afternoon,
The SSR you have selected is appropriated to your needs, only you have to be careful with the dissipation.If you use it without any forced air cooling, you can work with maximum 10 Amp at 25⁰C (see derating curve in datasheet)

If you have a forced air cooling, you can work up to 25 Amp, but you have to check the heatsink temperature: it must be lower than 100⁰C (you can measure it with a thermo-couple in the middle of the SSR, see picture below)


Regards.

I will be using a buried device at 16Amps, no air circulation but it has supposed thermal protection

perhaps should try to find another SSR or move forward with Crydom's one?

Thanks

 

[annlee]

Hi there buddies, I asked Crydom about the PF240D25 relay heating specs and this is what they said:



I will be using a buried device at 16Amps, no air circulation but it has supposed thermal protection

perhaps should try to find another SSR or move forward with Crydom's one?

Thanks

Latest news:

[FONT=sans-serif][SIZE=2]Hello,[/SIZE][/FONT][FONT=arial] [/FONT]
[FONT=sans-serif][SIZE=2]the PF240D25 cannot work at 16 Amp load without forced air cooling.[/SIZE][/FONT][FONT=arial] [/FONT]
[FONT=sans-serif][SIZE=2]Another option could be [B]UPD2425 [/B]([/SIZE][/FONT][URL="http://www.crydom.com/en/Products/Catalog/u_pd24.pdf"][FONT=sans-serif][SIZE=2]http://www.crydom.com/en/Products/Catalog/u_pd24.pdf[/SIZE][/FONT][/URL][FONT=sans-serif][SIZE=2]). [/SIZE][/FONT][FONT=arial][/FONT]
[FONT=sans-serif][SIZE=2]You must take care of the dissipation.
[/SIZE][/FONT][FONT=arial][/FONT]

[IMG]https://mail.google.com/mail/u/0/?ui=2&ik=37a18e3c0f&view=att&th=139d4bd5b529d8bb&attid=0.1&disp=emb&zw&atsh=1[/IMG][FONT=arial] [/FONT]

[FONT=sans-serif][SIZE=2]As you can see in the derating curve, you can work with 16A load at 30degreeC with a 5 C/W heatsink (you could use a metal panel for dissipation)[/SIZE][/FONT][FONT=arial] [/FONT]
[COLOR=#500050][FONT=arial]
[FONT=Arial][SIZE=2]Regards.[/SIZE][/FONT][/FONT][/COLOR]

So with this other SSR, the buried system would be under 30Cº if I use metal panel for dissipation + foam, I guess? :yinyang:

 

[KFH]

As has been said before burying an electronic device is a bad idea. I am sure people on here with more experience of cable joints than me will tell you that an underground fault is usually at the joint, and they are simple compared to an electronic device.

Part of good design is ease of maintenance, unless you are making disposable items, which most electronic devices appear to be these days but even then you would expect to be able to replace a component or assembly easily. Digging a hole to replace a device or even diagnose a failure is in my view not good design.

Draw up a list of pros and cons as part of your project to justify why it needs to be buried, it may even add a few points to your result.

 

[annlee]

As has been said before burying an electronic device is a bad idea. I am sure people on here with more experience of cable joints than me will tell you that an underground fault is usually at the joint, and they are simple compared to an electronic device.

Part of good design is ease of maintenance, unless you are making disposable items, which most electronic devices appear to be these days but even then you would expect to be able to replace a component or assembly easily. Digging a hole to replace a device or even diagnose a failure is in my view not good design.

Draw up a list of pros and cons as part of your project to justify why it needs to be buried, it may even add a few points to your result.

The reasons why it is buried: excellent protection against vandalism (important problem here), you dont need to dig if need to replace parts since it has a top with a lock plus a mechanism to extract it with ease, closer to the electricity cables where it is feeded, "low-cost" (one of the pillars of the project), tiny box, maintains lower temperature, it does not cause "impact" in the parade and it is discrete

The main cons are: worse refrigeration than cooling systems, humidity, not sure what other cons in comparison with its pros

:jester:

 

[KFH]

Ah, you do not appear to be burying it but putting it in an accessible underground chamber. That makes a difference to the cooling aspects and the accessibility for maintenance. The recommendations from others about using under rated components to minimise heat will probably still be valid. Will you get a reliable signal to activate the phone without an external aerial?