Kids Robot

I recently promised my daughter we would make a robot together, one that could make drawings.

After searching for some inspiration, I found a really simple one, here, that could be easily built and that she could understand.

So here are my plans, most steps, if not all, can be make by the children with some assistance:

Materials: a battery holder, motor, switch, tie wraps, and a piece of wood; some basic tools are also needed. I have pre-drilled the wood with 6 small holes for the feet, and 4 larger holes for the motor mount, and pre-soldered long wires to all electric components, so that the child can connect them.

Kids: Cut 3 lengths of solid core wire, strip it, and bend it to fit the holes, see next picture:

Kids: Mount like this!

Kids: Mount the motor with the tie wraps. Mount a thin flexible tube on the motor. Here I used a bit of thermo retractable sleeve. On the tip of that you mount a tip of a pencil.

Kids: Also the battery holder.

Connect it all via the switch. I used a push button, but a regular ON-OFF is also fine! even better maybe would be a ON-OFF-ON to reverse the direction!

Here it is a better view!

It then got decorated with antennae and mouth :) The kids really enjoyed it!!!

The idea is that the vibration both draws and makes the robot move. Mine was a bit too heavy to move, but I'll work on that!

I'm already thinking of the next ones! slightly more complex!

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.

CF to SATA adapter fix

Some time ago, I bought a motherboard (ASUS AT3IONT-i) and a large disk for a project I had in mind. It was the first SATA disk I ever bought, so I was curious as to how that worked.

Plugged it all, and the disk did not work...never got recognised. Strange.

After a lot of investigation, and blaming it on the disk, I remembered I had a CF to SATA adapter lying around bought in a trip to Taipei's electronics area, so decided to give that a try, to rule out the disk.

As I plugged it in, smoke! from one of the regulators. Very strange. Upon some quick investigation, I found out that the 5V and the 12V lines on the power cable were switched, the one that came with the Motherboard. I was upset and thinking of how would they look at me in the shop if I show up with such an argument, that the lines in the cable are switched.

But it was late at night, and I wanted to get it done, so I just disassembled the cable and reassembled it properly. Unfortunately, no pictures of that. All was well afterwards! Except for the adapter that was burned.

So last time I ordered something from Conrad, I remembered that, and ordered some regulators of the same kind. Tonight I did the switch! exciting, as they are SMD components, but it went much easier than expected! Here are some photos:

Burned regulator, AMS1117-3.3

 Regulator removed

New regulator in place!

Now the adapter will go into the black hole of computer components, never to be used again! but at least it is fixed!

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?

Switch Box

This weekend I finally finished a project that has been on my mind for quite some time: a Switch box!

In a few words, it is a box of electrical plugs, each with its own switch.

A few months ago we changed our old CRT TV by a new flat modern HD thing, mainly to get rid of the annoying little decoder box that we were forced to use in order to see the channels that we liked that were moved from analog to digital, and, since we every night switch off all devices, in the hardware switch we made sure the new TV had such a hardware switch.
So when we come home, all happy with the new TV, and switch, we discover that the nice sound bar that came with the TV not only required a separate power supply (plug) but didn't have a real switch, that allied to some devices hanging around that did not have a hardware switch (DVD player) which required a unplug action, until I hacked a light switch on to the cable, I decided to make the following contraption.

 Under side

 Top side

It is a series of 6 plugs, just like an extension cord, but where each individual plug has its own switch, UK style. I then hid it under the furniture where the TV and all devices rest on, with the plugs nicely hidden under it.
I think these things should be sold in shops! As a side note, I did consider having a remote control for this, using a micro-controller and some SSRs,  but that would complicate it, both in terms of build time, and safety considerations.
I am also not sure I it will ever recover its cost in saved energy, but hey, if we account for the energy I save going around unplugging devices at the plug, it already payed it self off today!

I hope you can get a good idea of the result from the pictures!

 

Mounted in place

Another view of it in place

Project finished!

This is it! The OpenTherm JeeNode/Arduino interface is finished! and all ready to roll!

The prototype had been working for almost two months now, and finally the boards arrived from fabrication, I think the result was worth waiting for, and worth doing it! I got three identical boards, so if I mess up one I can go on with the next:

Bare boards

Very simple, but very effective :)
I thien collected the components, whe to buy the optocouplers, and incorrectly bought the 4N35 instead of the 4N27 that the prototype used, but only realised after they were already soldered, so I tested it, and they work fine! crisis averted:

All ready for assembly

Mounted everything, both the JeeTherm, and a JeeNode v4 I had around still to be assembled, and put it all in the enclosure:

Assembled, and in the enclosure, attached to the JeeNode

Another view

Had to fiddle a bit more to get the screen fitting in the cover, and connected to the JeeNode:

All ready for action

Checked that it all worked, and got it connected, instead of the prototype. It is now running happily:

Talking to the boiler

I am quite proud of the final result, it looks good and well packed, and I tried not to cut any corners this time, took my time, and tried to do it patiently...very often I end up messing up things in the rush to get them finished.

It is now in beta test phase, if it works well for the coming days, then I will attach it permanently, now it is still floating :)

Already thinking of the next project!