RC revisited

Robbe Dusseldorf

Robbe Dusseldorf

Building RC boats and off road RC cars has always been one of those other (expensive) hobbies of mine. Expensive, especially when you’re still in your teens and your only income comes from a newspaper delivery job…

The last model i built was this Robbe Dusseldorf; i finished this one somewhere in the late 1990’s. After that, i did a few test runs with it but then it stopped. Somehow i’ve always been more of a builder than a user; once the building part is finished, i tend to lose interest and move on to the next object to build. The Dusseldorf was finished, and then came kids, domotica, lots of other things and before you know it, 10 years have past…

With our son reaching the age of 9 soon and given his interest in anything that looks ‘tech’, i thought it was a good idea for the next level: he already has 2 RC cars (and not those cheap things you buy in a toyshop, but the real deal!), but now it’s time to get serious 🙂

Graupner U-16

A few weeks ago i bought a Graupner mini Sub for his birthday to see how he feels about the ‘wet’ section of RC.. this idea stemmed from the fact that in the last couple of months, he’s increasingly asking whether he is allowed to sail with one of my RC boats soon… hmm, not yet, let’s first learn you the basics 🙂

To be able to use the 2 RC boats again that are still equipped with RC parts like receiver, servo’s and motors, i have started making an inventory of what needs to be fixed, ordered and/or replaced. For example i have a lot of lead acid batteries, that haven’t been charged in 10 years or so, so i guess i’ll have to buy replacements for those. A first inspection this evening also revealed some fishing wire that is used to move the water cannons, were broken. And i need to check all the electric wiring and see if the the extra functions still work like lowering the anchors, moving the water cannons, switching lights, radar, etc.

Internal inspection
Internal inspection

That will take a week or 2; by then my son will be practicing with his mini sub and when we’re both ready for it, it’s time for a ‘duet’ with 2 RC boats; the Robbe Dusseldorf sailed by captain Robert and the Robbe Schütze sailed by captain Remco 🙂

Testing PIR sensor

PIR sensor on my ASUS TOP

PIR sensor on my ASUS TOP

No, this is not some special add-on for my ASUS TOP.. it’s just a Duemilanove with a PIR sensor attached to it.

And the ASUS TOP, which is used as my Domotica GUI in the livingroom, is only used to provide power to the Duemilanove.

Somewhere in October 2009 i bought 2 PIR sensors, but after some brief testing these PIR sensors were stored in a drawer and nothing has been done with them since then. Since i intend to create my own motion sensor someday, i put one of these PIRs on a breadboard today, attached to an unused Arduino. Finally..

And of course, the most logical place to test this sensor and learn something about how it performs, is the livingroom. The office is to small to learn anything about how this sensor behaves with motion from different angles, distances and the output it provides. A breadboard with the Duemilanove , PIR sensor and LED, stuck to the ASUS TOP with tape, seemed like the best compromise for real life testing without making the livingroom look like it’s an extension of my hobby room. The other members of my family can live with this; in fact, my son is the most fanatic “tester” of all of us 🙂

From what i’ve seen so far, this sensor is sensitive enough to be used succesfully, although the digital output is not as stable as i expected. During continuous motion (as in my daughter dancing in front of the PIR for 2 minutes) i still saw the digital output dropping to 0 (meaning no motion) for a large number of short periods. Strange? Well, at least it’s not what i expected..

This means i’ll have to add some debounce logic into the code that handles this PIR to eliminate unwanted transmissions of  these “no motion” events; cause if i don’t, i’m pretty sure i can change batteries every couple of weeks when i create a battery powered sensor with it.

To be continued…

Floor heating vs energy saving

Once we had decided that there would be a new marble floor at ground level, it was immediately clear that a floor heating would also be needed because for most of us the main trigger for turning up the heat, is cold feet. But what effect would this floor heating have on energy consumption?

After the decision for the new floor had been made, everything went very quickly and I actually had little time to devote to the issue of energy consumption. I didn’t really like the prospect of having another power consuming pump in our house… but then there is always a good tip from Pieter 🙂

Pump consuming at least 44W...

Pump consuming at least 44W ?? 🙁

Normally, a floor heating comes with a standard pump, in this case from the Grundfos brand, including a pump switch. This pump switch switches off the pump at times when there is no need for it to run and thus saves energy.

Floor heating unit with standard pump

Floor heating unit with standard pump

However, nowadays there is an alternative, namely the Grundfos Alpha2. This is a pump which significantly reduces energy consumption. At least, that’s what is being advertised; time will tell how much of this is true… The extra cost for this pump of EUR 190 should be recouped within 2-3 years; for me a good reason to let the standard pump be replaced by this Alpha2.

Grundfos Alpha2 using 7W

Grundfos Alpha2 using 7W

The most exciting feature of this pump is called AUTOADAPT, which means the capacity (=used energy) is automatically adjusted to the demand. In the above picture you see my Alpha2 consuming 7W while the central heating is on.

This week i was finally allowed to turn on the floor heating (hey, we’re in the middle of May! I shouldn’t have to do this!) and saw this pump use 7-8W of energy, which is much less then a conventional pump would use. How this pump (which has to be  used without a pump switch btw) performs compared to the combination of a standard pump including pump switch? Time and a energy meter will tell!

JeeNode/ZigBee pressure sensor closed

Now that my Zigbee/Jeenode equipped pressure sensor is working for 3 months without any problems, it was time to leave the breadboard stage and move on to something more permanent. While ordering new Jeenodes at Jean-Claude Wipplers shop, i stumbled upon a post (i should read his daily weblog more often!) that showed me just what i needed: an enclosure that looked just right for this job. I ordered the Jeenodes, 2 enclosures (1 extra for when i mess up the first one and don’t want to wait for a second delivery..) and some other handy stuff.

First i sawed off the part of the PCB that i didn’t need, to decrease it’s size.

JeeNode PCB without RF part

JeeNode PCB size reduction

Guess what? Now the length of the PCB equals the internal width of the enclosure! Nice… I still had some battery holders laying around that also fitted quite well:

Enclose, batt holder and JeeNode

Enclosure, batt holder and JeeNode

I didn’t want to leave off the FTDI headers, so i used 6 straight headers and removed the plastic strip from the headers after the headers were soldered onto the PCB. With the plastic headers left on, the completed PCB was just a bit to wide for the enclosure, which caused tension and the enclosure wouldn’t close well anymore.

Next item that had to be prepared, was the XBee Breakout Board. Normally the top of this Breakout Board contains the 2mm XBee headers and the 0.1″ spaced headers are at the opposite side. I removed the bottom headers i soldered in when i used this board for other purposes and soldered 6 wires on it from the top, only for those pins i really needed:

XBee Breakout Board

XBee Breakout Board

Pin 1 (labeled Vcc) for Power, Pin 3  (labeled DIN) for transmission, Pin 9 (DTR) for controlling Sleep mode, Pin 10 (GND), Pin 11(CTS) and Pin 12 (ON) for the LED. This makes the Breakout board a lot thinner and the wires are coming out between the board and the XBee module.

After soldering the wires coming from the XBee board to the JeeNode, drilling a hole for the LED (which blinks when a pressure sample is being sent), soldering the wires and gluing the battery holder into the enclosure, it looked like this:

Almost done!

Almost done!

The FTDI headers are very handy now, for uploading the sketch with the JeeNode already inside the enclosure; cause all you have to do is open the enclosure, gently lift up the left side of the JeeNode and connect the cable. So whenever i need to upgrade the JeeNode, i don’t have to worry about connecting issues.

FTDI cable connected to the JeeNode

FTDI cable connected to the JeeNode

Now all there was left to do was moving the XBee module and the Pressure Plug from the Breadboard to their new ‘home’, add 4 batteries, click on the other half of the enclosure and.. my first WAF certified sensor was born!

Zigbee Pressure sensor