Started studying in university of applied scienes!

Actually, I started in this fall, but forgot to mention it earlier. I study in MAMK, as electrical engineer. So far so good!

New teensies; 3.5 and 3.6

Got bigger, still teensy. 

Even though teensy 3.2 has more than enough power and features to most projects, I bought still few 3.6's and one 3.5.

Comparison of 3.2 and 3.6.

Car voltage meter

Seems I totally forgot that I had blog looming around here, so I'll try to "fill the gaps now"

Car voltage meter

My car lacked of voltage meter. Someone might wonder what benefits will voltage meter give?

Of course, It'll tell what voltage does battery have. Since It is hooked to ignition switch, It'll tell us voltage right away on startup and how much voltage dips during startup.

Starting motor can take anywhere and even more than 200-400 amps, so dipping of voltage is acceptable during startup. But, what if voltage dips during longer trips?

That, tells most likely of alternator fault; alternator is not supplying enough current to battery to accommodate required load.  Other fault apart from low-voltage, is high-voltage.  I've encountered alternator fault when battery voltage rose up to 18volts. Obviously this doesn't bode well for 12v system, so I could add more load to make trip possible towards home. With load, voltage dropped around 14v so it was in safe zone.

Digital version

Right, now off to how I made it. Initially, I made 7-segment style voltage meter, but due sunshine, digits were impossible to read, it

 looked cool though during darkness;
Control circuit in digital version was bigger than in analog, since led-display needed control of It's own. I used AtTiny85, mikrocontroller, to control display and read battery voltage via voltage divider, fed to ADC (analog to digital converter). I don't have, nor need, AVR programmer. Instead, I used Arduino as ISP (in circuit programmer)

Analog version

Added benefit along with better visual readability during sunlight, is better UI during quick glace.
It really doesn't matter is battery voltage 12 or 12.1. With analog meter, I just look and determine, Ok, It's close to 12.
Of course, I added something extra, and this extra was intelligent backlight, depending on voltage reading. This is accomplished by code, window comparator. I saved some space and few pennies when I used microcontroller to measure voltage and to control backlight leds.

Schematic is simple in analog version:

RGB-led fan ''speedometer''

Title says it pretty much all. Basic idea is the same as previous fan pwm/speedometer control, but rgb led needed bit different approach. all i needed was RGB colours, not all colours what are available, neither colours on the same time. So, i used window comparator circuit to sense voltage levels low/medium/high, and chose led colours RGB in that order. This circuit doesn't have hysteresis connected, i was lazy to add it to his design. But hey, it works :D

Recycling: BROKEN file/folder/map.

Well, the title may be bit confusing, i dont tell about recycling paper files/folders, but instead, i thought it would be good to share this info, if someone is interested .
So, i found that my loved paper file/folder (what is it called anyways in english, book-like thing you put papers inside to keep them organized?) decided to break apart. Nothing big, but the mechanism bended over, so it didn't serve well anymore. Normal people would throw it away, and buy a new one. But what i did, thought a moment, ''any further use for this?'' and bingo, i took it more apart, salvaged; couple stiff enough cardboard pieces to be used as cutting/drawing board, not smooth thought. Handle that shuts mechanism, would make great bended chisel, only needs handle and sharpening. And small bars where you put papers, make good clothes or other hangers, only threads needed and base to install them. YES i may sound bit cheap about all this .

Found from local recycling center: yet another electric typewriter

Due to nice weather, i decided to take little tour to local recycling center, havent been there a while. It seems it was indeed worth it, as i bought another typewriter, AEG olympia mastertype 100i, for 5 euros. Last one was indeed great find, and as it turns out, this was too, even better. And, in WORKING condition.

Last on had safety-earth, this didn't have such luxuries, but there are no metal parts much to be earthed either, so 230v socket was euro-style, 2-pin.
Power boards transformer has much more windings, and ffiltering caps are same brand as earlier, also, fuses of course. control board has 74 family logics, motor control IC:s, couple memories and cpu's of some sort, lockable mini-ide connectors, power resistors and discrete components. PCB at ink cassette assembly has bunch of connectors, opto-coupler plus power resistors & lockable mini-ide connector. Couple more opto-couplers were found at ink cassette too, and paper roll has one too. Again, solenoid took care of letter-punching.
Keyboard has couple IC:s, 74 family, and 5451 led display driver, plus discrete components.

Repair: 12v tower fan. Teardown also

My tower fan stopped working, so i figured i should take a look at it. it was surpsing hard to open in the end, but was made possible, nothing broke up.

Repair itself: At first, nothing really showed up, no bulged caps or anything else sucpicious at first. I measured the voltage pins for transformer, and it turned up to be okay. Then, when i plugged it, somewhat bigger spark came from dc-socket. I measured supply voltage pins for controller chip, 5v as datasheet says, so at least it gets supply voltage. After that, i realized that couple of smd-transistor were pretty warm, hot actually, so i measured them just to make sure they are not SC/OC, they turned out to be just fine. But, then i felt AHA, when i saw possible fault. One of the caps leads were left too long, and it was bent over to wrong place, causing SC. No wonder there was spark at dc-socket. I snipped feet smaller, and 'voila, repair success. Also, i noticed couple bad solderings, which i repair too. Well, i guess made-in-china says it all, but why it worked before just fine?.

But, i took photos also, so here comes teardown:

Inside was 12v brushless fan, and some cind of synchronous 12v motor, for pendulum movement. Pushbuttons for speed adjustment at 3 steps, pendulum on/off, and main power.
The ''brains'' are HT46R47 battery charger controller. Funny, this is fan, not a battery charger, but as it turned out, this controller has PWM output, so nothing strange there after all . I played around a bit when i was measuring the output waveform of PWM pin, and yes it indeed changed duty cycle as speed changed. I also stress-tested system too, by braking the fan, and controller responced by increasing duty cycle. Also, i found out that 1/10x at scope probe really matters, when i measured at x1 position, the was more noice, and fan shutted off. At x10, no problem.