Aquarium Controller Circuit Design Advice

Hi my name is Nathan,

I'm new to both this forum and Arduino in general. I haven't done any electronic since my High School days and that was a long time ago :slight_smile: . Not being one to do things by half I've decided to jump in the deep end and try creating a controller for my aquarium. I've found a great package at Google Code Archive - Long-term storage for Google Code Project Hosting. that I think has started me in the right direction. But I would rather have a web interface than the LCD screen and I've had trouble finding some of the components that he used. Long story cut short is I have come up with the following circuit design and would like some input from people with far more knowledge that I have on electronics.
I don't have the hardware as yet, as I will have to order everything online due to my location and I would prefer to get everything in one hit to save on freight. But I will be getting an Arduino Mega 2560, protoshield, and an ethernetshield. Plus what ever else I might need. Any advise you can give or improvements to the design would be greatly appreciated.

You have two temp sensors driving the same wire, I don't think that will work. You do have a few spare pins.
EDIT: I see now they are 1-wire sensors, but they are labeled TMP36.

Driving FET gates directly will work but it not best practice, maybe a ~100R series resistor.

4 of those FETs only drive LEDs, the Mega pins can do that directly (through a resistor) if they are just normal LEDs.

Is the other FET good enough for your motor?

No snubbing/flyback diode across the motor.

There are no pullup resistors on SDA and SCL.

Your caps are across 10v, they should be at least 16 or 25v versions.


Rob

Thanks Graynomad,
The LED's are high power and a lot of them, I'm using Meanwell Drivers http://www.meanwell.com/search/lcm-60/default.htm that accepts 10v PWM for the dimmer. Hence the need to step up from 5 volts.

The fifth FET is just driving a small computer fan that also accepts PWM, so the FET can handle that no worries from what I can see.

I'm not entirely sure what you mean for the pull up resistors on SDA and SCL. Would I need to add a 4K7R to the 5V rail just like I did for the temp sensors?

Would I need to add a 4K7R to the 5V rail just like I did for the temp sensors?

Yes, I2C is an open-collector style interface, it needs pullups.


Rob

Thanks Rob,
I have taken that all on board and modified as you suggested.

What a great community :slight_smile:

Hi Nathan

Those drivers look pretty good, but they are also pretty expensive, especially if you are going to be using a few of them. A lot of people are currently using the Meanwell LDD series which are small and relatively cheap although they don't have quite the level of flexibility as the LCM's.

And, the Stilo sketch has been around for a while now and has been used as the base for a number of other Aquarium Controller builds.

But, if you have limited Arduino, or more specifically C++, experience then I think you might struggle to integrate your planned Web interface - it is often harder to integrate something into an existing sketch than it is to start from scratch.

I was in your position 4 years ago - my Aquarium Controller has been running without problems for a few years now and I am currently finishing off a Touch Screen LED Controller. If you are trying to learn the programming language at the same time as building your controller then you need to take baby steps and have a lot of spare time.

Good luck.

Hi Magicj,
I can get the LCM at a reasonable price from a supplier so I figured why not :slight_smile:

The programming side of things shouldn't be a problem, I've been tinkering with code for many years, but all the same, I plan to start out small and work my way up. I'll begin without the web interface, but design the code in a way that its not such a big step to start adding it later.

Does any detail in the drawing warrant that it be uploaded as 5619x4044 pixels in size? Please try to shrink images before posting.