a n d r e a s . s c h u t z

Today i bought a BLDC hub motor! Why? I don’t know really. Well of course I know why, but I haven’t got an application for it.

I want to learn how to control it. I want to use cool PIC microcontrollers that I recently have started to program again. And I want to fiddle with optimization on driving it with torque and power saving. But do I need it? Silly question, all we actually need is to choose and to die!

The motor was cheap. But it didn’t come with any documentation what so ever. So my idea is to post information about it, and my progress with it, as i proceed.

Here are some data I have collected:
On the outside it is marked with 24V26C JS08030167

And when i took it apart:
3 poles, 36 teeth
40 magnets
3 hall effect sensors
2 ball bearings
3 thicker wires to the windings
5 thinner wires to the sensors (two for power and three for outputs from the sensors)

The hall effect sensors are three pin and connected like this:
Red +
Black GND
Green output from sensor one
Yellow output from sensor two
Blue output from sensor three

I added 5volt over the red and black wires and measured volts at the outputs while i slowly rotated the motor with my hand. I made a quick table over the values I got, it looks like this:
As we can see, one is always off. But i’ll have to read more about hall effect switches to know exactly what that means.

I read some more about different hall effect sensors and it seamed that the most common one (and the cheapest… a good way of finding out what is inside consumer products) is to be treated as a transistor witch sourches about 25mA. So I decided to drive som LED’s. Here is the movie:

Rename the file to whateveryouwant.3pg. It is a bad quality phone video, but it will show the rythm om the sensors quite well. When I reverse the rotation of the motor the sequence of the LED’s simply reverse too.

The overall quality of the motor is varying. Mecanically it is well made, but when it comes to the wireing and hall sensors it lacks bigtime. Even the thread is very poorly made and one of the bolts was broken on delivery. Like other chineese stuff I have seen it is a strange combination of high ambitions and unnessecery poor workmanship.

Here are some pictures:

As you can see there is som kind of marking inside the motor. I dont understand chineese. If somebody can read the markings, please let me know what it says.
Somehow I believe that theese markings is the factory name. Maybe this can help me in finding some documentation.

I think I have found my favourite way of driving the motor. I have been heavily inspired from http://www.ltu.se/polopoly_fs/1.35847!elektronikrapport.pdf and the BALDOS project at LTU. By reading their description and looking at their designs I finally found the missing link between the RC hobby motors and the more heavy duty hub motor.

I also finally found enough courage to energize the motor windings. I am by no means good att power electronics and I dont want my hub motor to end up in flames. I have been studying different ways of limiting the current to the windings to prevent melting while elaborating. I ended up using thin copperwire so that this thinner wire would melt long before the motor took any damage. I now know that the motor move when using only 12V. That makes things a lot easier to elaborate with since I can use a car battery.

I have decided to make the driver electronics in modules. That enables me to change some of the modules without starting all over again, should I regret any of the designs. I have settled on the following modules:

* CPU module, containing microcontroller and surrounding electronics.
* Sensor module, it will be nothing right now, when I use the hall sensors, but who knows, maybe I’ll try a sensorless design later.
* Driver module, containing the power electronics like the mosfet’s and their drivers.
* MMI module, the interface to us humans. Maybe a gas handle or a laptop application.
* Charger module, for battery charging. From 220 and regenerative from braking.

In practics I already have the CPU module. Several of them! Sensor module is not needed right now when sensors can be attached directly to the microcontroller. So the first module to build will be the driver module.

I think I finally found a good design for a driver module. My Idea is to have the IC IR2130 as a driver circuit. It contains some safety functions that could come in handy.
As the power-hexfet I think i will use IRFP460. It is one of the hexfets that is powerful enough yet almost affordable.
Each phase will be driven by a circuit like this:

Hi again.

My mediacenter uses an old but well sounding amplifier. A while a go the lights illuminating the front of the amplifier died. Last night I totally lost patience with the gloomy look of my dark amplifier and ordered some blue LEDs (nowadays they have to be blue, don’t they 😉 ).

My first plan was simply to exchange whatever lighted up my amp. with the LEDs.

My first plan…

Then I changed that plan.

Ever since I put my mediacenter together I have tried to figure out how to control the volume on my amp. The problem is that it has a nice, soft sliding pot. with a fat feeling and I don’t want to remove it.
I like the pre-80-ish look on it and I don’t want to ruin that either (just to hot it up a little with the blue LEDs).

I think I will try to motorize that pot… I think. And I think I will do it with a serial connection to the mediacenter… I think… If I can… the mediacenter with its remote will control the amplifier and I won’t have yet another remote on my table, and the mediacenter can fade down the volume when it shuts down… nice.. If I can.

Well, well… My first step is to exchange the broken lamps with the blue LEDs anyhow… stay tuned.

——————-

The LED operation went well… maybe to well. Those high effect LED’s really are _blue_. Well I asked for it. Blue I wanted and blue I got. Anyhow, it really shines in the dark.

From time to time my fingers start to itch. When that happens I just have to build something… now it is time again.

For a while now I have been irritating my self on those silly radio shows that I have to wake up to. And ideas of building a wake up device have started to crystallize.

Readers of my blog know how I tried to build a music workstation, and how I found out that the computer I used turned up to be to weak.
Well… I still have that computer, and the idea of a multimedia enabled alarm clock is forming.

Design idea

a 17″ LCD monitor
a mATX FS motherboard
some 500 Mb memory
a 1GHz celeron processor
a wireless KBD
a PS2 mouse pad
and a 1Gb CF card with an IDE adapter

…lets build an multimedia alarm clock!

The LCD monitor, beeing salvaged from my work, have four holes on the back. I think they are supposed to be used for a wall mount or something like that. I used them to mount a simple slimline chassis. I had it made for about 75 SKr.

I mounted the chassis on distances so that the cooling outlet from the monitor would not be blocked. I drilled holes for standard motherboard mounting distances and mounted the motherboard as in any normal computer case. I then glued plastic “rails” made from a CD case on the power supply and pushed the rails in the AGP and PCI slot connectors. Making the power supply “piggy backed” on the motherboard.
The CF-card and the IDE adapter is located under the ribbon cable. And as you can see there is plenty of room between the power supply and the MB for cooling.
Here it is, all hooked up and “ignited”. I used double CPU coolers to get enough passive cooling. The slimline case i had made also have a perforated cover that I have removed to take the photos. With the cover on, it looks almost as a commercial product. Well… a little bulkier.

As you can see, one of the problems that arises is the length of the normal cables. I yet have to get very short cables for monitor (both VGA and power) and sound. I also haven’t integrated my wireless kbd reciever. It is supposed to be mounted to the left of the CPU cooler.

I installed the latest version of SLAX and configured it heavily 🙂
The use of the “toram” cheat code is used to minimize CF wear and to make the system nice and fast.
The monitor have built in speakers that sound far better that my old clock radio and the KDE desktop is configured to be “fool proof”. Only a handful icons are used. One for gmplayer, one for juk and one for the KDE settings panel. If it is possible, the mouse pad is just temporary.

A numpad keyboard is used to make the remote control. I bought a cheap but good looking numpad and modified it with “the brain” of an old wireless keyboard. Then I remapped some of the keys in X so that i get the functions i want on board the numpad. The TAB key and the SPACE key for example. Here is a picture from the inside of the numpad.

The gutted numpad leaves just enough room for the wireless transmitter and a 3 volt battery. The transmitter is the same model as my (tucked away) wireless keyboard. So I can “sync in” a normal keyboard for maintainance.

So what can I do with my MediaClock?

* It is sharp on time because it uses NTP to correct itself
* It plays the music I want to wake up to, via USB or network
* It plays movies so that I can watch film in bed
* It is online so that I can stream news and shoutcast radio if I like
* It is a skype phone, used to communicate both in the house and like a normal phone

So are there any disadvantages? Cause there is, 17″ is to big. But it is the only left over monitor i have. If you decide to make a MediaClock, rather use a smaller monitor.

Hope I could give you some inspiration…

*** UPDATE ***
The 17″ screen is now exchanged with an 15″. That doesn’t sound to big a change, but believe me it is. MUCH nicer with that smaller monitor on my sideboard. Apart from that the media clock have served me extreamly well. It has only failed once after a power outage. For some reason it didn’t mount the music volume when it came up, so the alarm didn’t “play”. After that it have conducted well, even after several power outages.

*** UPDATE ***
Today I upgraded the system on the mediaclock to SLAX 6.1.2. I also added a script that turns on xclock at a given time interval, seven o’clock and one hour forward right now. That idea came from my wife who wanted to know the time while getting ready for the day. The media clock continues to perform very well, and by now I havent had a more reliable alarm clock on my sideboard.

This category is about building what I have decided to name the “composersBOX”. The box itself is as little fancy as my urge for it is big and it will be built using as little hardware as possible.
Here I (and hopefully you) will diskuss issues and show the results in the design and work with composersBOX.

What is composersBOX?
The composersBOX is a computer that will aid in music production. It is a computer that will try to be as useful as possible when it comes to MIDI, softsynths, sequencers and recording. The following statements will guide in desinging and building composersBOX:

@ composersBOX will as much as possible be bulit on ready to buy hardware.
@ composersBOX will run open source software.
@ composersBOX will try to be dirt cheap.

What composersBOX is not!
composersBOX is no fancy all in one power tool for proffessionals. Nor is it a “brag box” to impress your friend (or whatever). I do not have the possibility (or the will) to pour a lot of money in composersBOX. If you are one of the persons that gladly pay 15000 SKR for a system, then you can buy things like this that are ready made and ready to run… enjoy. But if you (like me) look at computers like designated systems that use their resouces to their purpose, solely. Then, maybe, you will find usefull info here. And what the heck… it’s fun, and it will lower the pile of computer trash in your wardrobe 🙂

HARDWARE
I have decided to use an old FujitsuSiemens motherboard simply because I had one lying around. It happened to be a D1215 motherboard featuring a 400MHz processor, 256 Mb of RAM, onboard sound and NIC. Not much, but at absolutely no cost.

My collegue found a 1MHz processor that I used instead. The D1215 motherboard required a BIOS update and a microcode update to accept the newer processor. The update is downloadable from FujitsuSiemens for free.

I have ordered a IDE to CompactFlash adapter and a 1Gb CF card. In that way composersBOX can be more quiet and the later to come DVD burner can be easily freed. After some googling a found a CF adapter for 100 SKR and a 1Gb CF card for 150 SKR.

My idea is to build composersBOX so it can be a part om my stand. If I give it the right dimentions it can fit neatly under the synth modules. I have yet no idea where to put the computer keyboard, the mouse or the monitor. Any ideas? I do have a salvaged mouse pad from an old laptop, maybe that could com in handy? I also have an old frontpanel from a bridge, it looks like this.

As you can see it features a 2X16 LCD display, three momentary push buttons, a DB9 female connector and some LED’s. It has a 2X17 pin connector at the rear wich I haven’t investigated yet, but at first glare it looks rather straight forward.

Ok, my IDE to CF adapter and the CF-card arrived last friday. FUN! I spent some time this weekend trying to install and boot from them. It was trickier than I had thought, but finally I did it right and got it working. I don’t know why but the SYNC command where really essential to get files onboard the CF-card. I think I screwed the files about ten times before I got them seated on the card. The istalled systems (yes I made two of them) are MUSIX and DSL. Now my quest is for cooling, any slient ideas? PLEASE? All fans I have tried sounds like jets. Is there really no way to cool 1GHz in a passive way?

The ideas for the case are growing. I think I’ll skip the DVD-drive, to clunky and to old fashioned. And I will build a perforated hood to enhance cooling. As soon as I have the material I’ll post some pictures.

MIDI INTERFACE
Last year I invested in a MEDIROL UM-1 USB to MIDI interface and the motherboard I am using does not have the gameport/midi connector. But if you have a motherboard that do have the gameport/midi connector this
or this
scheme from John
Loadsman might come in handy. But as I stated above, the composersBOX will be built from ready to buy hardware.

SOFTWARE
As stated, this project is going to use open source software.
I like the idea of live CD’s. That kind of operative system let composersBOX to use a diskless design.
Distros like JACKlab, AGNULA and MUSIX are beeing tested. Theese distros represent an impressive achitecture and a vast program flora. To come up with a home built distro like one of theese would take me years, if ever.

After some fiddling with the different distros I have found MUSIX to be the one I like the most. AGNULA have been discontinued and JACKlab is very beta. MUSIX on the other hand is a live CD (jacklab is a DVD) and it is based on KNOPPIX of wich I have som experience and it is PACKED with music making software.

One other aspect of MUSIX is that it is a live CD. Perfect to combine with CF booting. A “normal system” will wear out the CF-card, but if you treat the cad as a CD… it will last a long time.

I have been slow lately. No updates, no reports on composersBOX. The reason for that is that the preliminary tests on my machine described above where dissapointing. I got it all working and started to use the box a little. It did not keep up with me for long. It is to weak, and I think it is the processor and/or motherboard (read: chipsets). I will keep you updated as soon as I have another machine to fiddle with.