Fan Controller reloaded II

So here is the continuation of the previous chapter, the saga for a nice product.

Final version:

The eagle eyed among you might notice some small changes. Nothing major.
The ones really paying attention might notice the mistakes: DS18B20 is one wire, not I2C, as is indicated (cosmetics), and the silkscreen for the 12V and the 5V regulators is inverted (cosmetics with high potential for disaster). The soldering holes for the screw connectors could also be a tiny bit bigger, but that depends on the connectors used (could be problematic, as I used some big ones).

I only noticed these mistakes after the boards arrived, luckily before soldering the regulators, so no harm done!

but, following the intense design sessions, I sent it out to be manufactured by Fritzing, and the boards arrived, a bit more than a week later! Great service is all I can say. Here they are in all their glory:

 I really think they came out amazing!

And here in the box, with some components located, not soldered yet:

And finally, in the box, with the components (attiny is missing):

In the third chapter, the completed thing, with screws, micro, lid, everything! and some considerations for improvements.

Fan Controller reloaded

I've been busy redoing my fan controller, and now, that I'm about to post about it, I just realize that I never presented the previous work finished, so here's a picture of the prototype:

So there it is. I especially bought those little orange and gray connectors to try out for this project.

It had been working fine for one year, but the power supply that comes with the radiator is in a DIN rail format, so I have been wanting to find a DIN rail enclosure, and make a PCB to put inside it.

I found a nice box in Conrad, and proceeded to make a shield for a JeeNode, that would fit the box. I decided to use Fritzing, to try out the manufacturing service.

1st attempt:

Great! only to realise, that the JeeNode on top of this would cover the access to the screws of the connectors. Not to mention, that the box had some mechanical constraints.

2nd attempt:

Notice that I have completely replaced the JeeNode by a Attiny of 8 pins. I decided I do not need statistics on this. So it is now a fully standalone micro-controlled controller.
notice also the mounting holes in the middle, and a big hole for a big plastic column in the box (pictures will follow). Time to print the thing and check that it fits.

3rd attempt:

Of course things didn't really fit, so I had to shift a few things around. I also decided to add some connectors to make the whole thing tidier. This is almost it! 

In the next post I'll put some pictures of the final product: beautiful boards, made in Berlin! and the assembled thing.

Fan controller

As mentioned in the previous post, I am busy with changing a radiator here in the house, and, as part of my investigations into heat distribution efficiency and space efficiency, I decided to try a radiator built in the ceiling with forced air circulation.

This will be placed in the bedroom, in the ceiling, so out of sight, apart from the ventilation grills, in the attic.

The radiator receives the heat from the standard hot water circulation system, and uses a ventilator fan to take the heat to the room.

This particular unit has a 24V DC motor, whose speed is controlled by a 0V to 10V signal, so, like I mentioned before, I built an amplifier which takes a 0 to 3.3V filtered PWM JeeNode output and multiplies it by 3, giving me a nice 0-9.9V. Here is the schematic, made using Fritzing:

It works, a basic test with a very slow sweeping output turns the motor on slowly, ramping it up to maximum speed, and back again to off.
The controller in the JeeNode will read the input and output temperatures using a pair of good old DS18B20's, and controlling the speed accordingly. I am still developing the algorithm for that (will certainly pass by some sort of PID controller).
I don't really plan on using the JeeNode radio for the control part, but will certainly be feeding back statistics later on!
The regulation of the water will be by means of the FHT8V which has now been serving in the room for the last 5 years or so!

This weekend I'll disconnect the current radiator, which takes a huge amount of space in front of the windows, and start the process of assembling the new one. We'll move to a spare room for thermal confort!!

PWM

For an upcoming modification to the central heating I need a controller capable of outputting a (standard?) 0 to 10V control signal.

Of course, this is a job for Arduino/Jeenode, and not for some store bough industrial controller.

Since the JeeNode works at 3.3 volts,  I set off to build an amplifier, using an LM358, wired to multiply the input by 3 times, which gives a nice and convenient range of 0 to 10V!

I am still in the process of building the circuit, but for this I needed to get the oscilloscope out.

Once I had the work on the breadboard ready I captured the following images, I thought they were nice.

I wanted to have both lines in the same shot, but my channel B is not working well, so I can only use one channel of the scope.

After I shot these, I proceeded to blow up an LM7805 (why does it have a different pinout from the LM78L12) and consequently blow up my old trusty JeeUSB version 2...I hope I can bring it back to life.

Just a short mention of what the project comprises: 0..10V controller for a 24V ventilator fan, and two Dallas 1820 measuring the temperature of the water flow (in and out). The motor will be controlled based on these.
Soon the circuits and protoboard pictures, later custom PCB's?