VoltaLumen bus stop LED screens

november 17th, 2014
by jaanus
Demo of a installed bus stop screen that is not working at the moment

Demo of a installed bus stop screen that is not working at the moment

So Estonian LED display company VoltaLumen installed bunch of LED displays to bigger bus stops in my home town Tartu. As always - this requires a teardown. As it turned out - taking it apart without destroying it is practically impossible. It has been riveted shut and painted over. That stopped my teardown a bit.

In the accessible hatch there was bunch of debug connectors. RS485 for control over the wire, USB for programming, SD card slot for flashing firmware and GPRS modem slot. RS485 and 230VAC connections are brought out of the screens via nice cable for local controlling. Information is sent over RS485 in XML format to change bus times and clock. It also has an internal RTC, so clock synchronization doesn't has to happen every day.

From LEDs side - it uses orange PLCC2 leds. Quite high brightness, blinded us several times in the lab. Fortunately there is brightness control.

 

Overview of bus stop LED screen

Overview of bus stop LED screen

Insides of screen maintenance panel

Insides of screen maintenance panel

Close up of the LEDs

Close up of the LEDs

Share

Posted in Teardowns and reviews | Comments (0)

Infrared LED matrix

november 12th, 2014
by jaanus
Finished soviet infrared led matrix

Finished soviet infrared led matrix

I have lately been doing bunch of different LED matrices. One of the most interesting one is an infrared matrix, made out of old Soviet infrared light that was used for data transmission (if I remember correctly - in studios). We repurposed it to LED screen that is visible only through cell phone camera.

We stripped out the insides of the device and mounted in our stackable led controller boards (link to github source). These two boards are designed to convert random amount of LEDs to Arduino controlled matrix. There is high side controller - 8 P-channel mosfets per board. And low side controller uses TI TLC5940 16 channel led controller. Low side board is stackable sideways, since I originally used it to control 8x70 matrix made out of cell phone backlights.

Insides of the device. Two driver boards, voltage regulation and Arduino Fio.

Insides of the device. Two driver boards, voltage regulation and Arduino Fio.

 

Sneak peek to our new project - wood screen

Sneak peek to our new project - wood screen

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LATspace educational CubeSat kit

november 3rd, 2014
by jaanus
LATspace educational kit

LATspace educational kit

Ventspils University College in Latvia got itself a kit to teach cubesatellite technology to students. The kit was developed by company called LATspace. I got my hands on it and made pictures of everything.

Piece of frame and Remove before launch pin

Piece of frame and Remove before launch pin

The kit is made out of normal components so it won't work in the orbit, but it is a good studying tool for students. The cool element about the kit is that power supply and ADCS board are with same design and for different systems different parts of the PCB were populated.

EPS

Power system consists of small cheap solar panels mounted on PCB side panels. For storage there are two normal 18650 lithium ion cells and to charge them - two little linear charger chips.

Also with the system came external big battery and charger units. Probably because space industry really likes big bulky systems with D-subminiature connectors.

Attitude control and on board computer

On earth you cannot two thee axis attitude control because you have gravitation. But when suspending the model with a string, you can make attitude control around one axis. This system has one axis of reaction wheel that is controlled by L298P motor controller. The motor is a normal brushed DC motor with small flywheel attached. On the board there is also two axis magnetorquer controlled by the same motor controller chip. I couldn't find any sensors, but I presume they were hidden away to somewhere where I couldn't get.

Programmable assembled satellite model

Programmable assembled satellite model

On board computer is just an empty board where you can mount your Arduino. There is also Xbee for communication and microSD card slot.

Solar panels

Solar panels

Power system on the satellite

Power system on the satellite

Demo battery units

Demo battery units

Battery controller

Battery controller

Another battery controller

Another battery controller

Underside of ADCS board

Underside of ADCS board

Communication system with Arduino mount

Communication system with Arduino mount

Programmable assembled satellite model

Programmable assembled satellite model

Posted in Space | Comments (0)

Aoyue 950 soldering iron and vacuum pen

oktoober 27th, 2014
by jaanus
Aoyue 950 unboxed

Aoyue 950 unboxed

After another frustrating desoldering session I ordered desoldering hot tweezers. Because I don't know how much will I use it I bought the cheapest - Aoyue 950. The price was about 50 € with shipping.

It came with two sets of tips: sharp and big blocks. Big blocky ones looked fine but the design was so stupid that it didn't work on any component I had.

Next - I teared it apart. The insides look like normal cheap chinese station. Big ugly transformer and even uglier piece of electronics.

In the end of the day - device works, makes desoldering of some components easier. As a common tool I would recommend hot air station first but to a bigger lab - this is a good tool to have for those nasty situations where other tools are not so suitable

Insides of the Aoyue 950

Insides of the Aoyue 950

Cracked bottom from the transportation

Cracked bottom from the transportation

 

 

 

 

 

 

Double vacuum pen

Double vacuum pen

I also got a vacuum pen. Useful when using solder paste method to assemble PCBs. It is a small box with a speed control button and two vacuum heads. Mechanics are exactly the same as in regular aquarium pump. It uses two channel diaphragm/membrane pump to make the vacuum. Another trick I like is that they use non filtered mains to move pump up and down.

Device itself comes with different tips, but for small components it is best to use syringe tip on original nozzle.

Insides of a vacuum pen pump

Insides of a vacuum pen pump

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Rail drilling machine

oktoober 19th, 2014
by jaanus
Finished rail drilling machine

Finished rail drilling machine

Me and my friends mechatronics company EDM OÜ cooperated. The result - automated drilling machine for a factory. Machine uses stepper motors to move aluminium rails and drills holes in them. Then it uses a saw to cut it necessary length. The machine is controlled from touchscreen connected to raspberry pi. Software gets in files with drill and cutting information and sends commands to low end. In the low end there is an Arduino Mega that controls bunch of stepper drivers. As necessary for such devices - everything is optically isolated.

EDM made all the mechanics and integration. I designed and made the control electronics and wrote the software. The most interesting part was writing stepper pulse generator with acceleration and deceleration. Also we found out that rotary encoders need interrupts to give proper feedback, because of small vibrations.

 

The mechanical beauty in the machine

The mechanical beauty in the machine

Mechanics moving the drills

Mechanics moving the drills

EDM made 4 axis CNC machine used to make components for drilling machine

EDM made 4 axis CNC machine used to make components for drilling machine

The case of the machine lying in EDM workshop

The case of the machine lying in EDM workshop

Insides of the electronics cabinet in the beginning - Arduino, Raspberry, stepper drivers and other necessary components

Insides of the electronics cabinet in the beginning - Arduino, Raspberry, stepper drivers and other necessary components

Night of software development, my cat quite liked the warm touchscreen monitor

Night of software development, my cat quite liked the warm touchscreen monitor

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Tartu Mini Maker Faire

oktoober 13th, 2014
by jaanus

There was a mini Maker Faire in Estonia in the city I operate. I was out there with my electronics development company Tech-thing. I met bunch of awesome people, saw cool projects and met up with old friends. Because Estonia is so small, practically everybody were there.

Music triggered flamethrower head

Music triggered flamethrower head

Prototaip CNC showcase

Prototaip CNC showcase

First I saw Prototaip, a mechanical R&D company. List of other friendly faces: Wazombi labsIntelligent Materials and Systems Laboratory, Skeemipesa, robot mannequin project (Fits.me), Idea lab protocenter. There was probably bunch of more people who I forget but they know who they are.

Overrall impression was really good. The place was packed with 3D printers and kids. Didn't expect so much of either. I am waiting for the day when everyone has a 3D printer and then they go - now what.

I also talked with couple of DIY guys about 3D CAD and most of them seemed to use sketchup. Seems reasonable since it is so easy, but on the other hand - it is the most awful program to use for mechanical drawings. FreeCAD wins on every day (and of course bunch of commercial programs).

I had lots of fun and I hope that Maker Faire will be back to Estonia soon.

Wazombi labs with their 3D printer and RollyCat cat toy

Wazombi labs with their 3D printer and RollyCat cat toy

Some guys with self built CNC mill

Some guys with self built CNC mill

Tiny robots made from electroactive polymers by UT IMS Lab

Tiny robots made from electroactive polymers by UT IMS Lab

3D printers

3D printers

More 3D printers

More 3D printers

Some bigger delta style 3D printers

Some bigger delta style 3D printers

Bit of 100% handicraft computer

Bit of 100% handicraft computer

More self made computer with its maker

More self made computer with its maker

Skeemipesa exhibition - lamp radios

Skeemipesa exhibition - lamp radios

Guys from robot mannequin team

Guys from robot mannequin team

UT Idealab protocenter with its makerbot

UT Idealab protocenter with its makerbot

Brainwave controlled copter

Brainwave controlled copter

Other people making pictures

Other people making pictures

Some machine, patented!

Some machine, patented!

One of the makers of the machine

One of the makers of the machine

Solar cell soldering workshop

Solar cell soldering workshop

Led thingie soldering workshop

Led thingie soldering workshop

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Tartu Observatory labs

september 23rd, 2014
by jaanus
Primary electronics lab in Tõravere

Primary electronics lab in Tõravere

I have been working closely with ESTCube satellite project that is developed by Tartu Observatory. Tartu Observatory is Estonian space technology centre that does space science and builds satellites. Couple of years ago they got a new building and now the electronics labs have been shaping up too. I am working closely with them so I use the laboratories and testing facilities quite often.

Anechoic chamber, 50x50 cm unit size and up to 18 Ghz measurements.

Anechoic chamber, 50x50 cm unit size and up to 18 Ghz measurements.

Spectrum analyser and 18 GHz test antenna.

Spectrum analyser and 18 GHz test antenna.

Climate chamber  temperature (-40 to +150) °C, humidity (30 to 90)%

Climate chamber temperature (-40 to +150) °C, humidity (30 to 90)%

Vibration bench  and the amplifier

Vibration bench and the amplifier

Big (220L) thermal vacuum chamber (-40 to +250) °C

Big (220L) thermal vacuum chamber (-40 to +250) °C

Big ground station for satellites

Big ground station for satellites

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HUB75 RGB LED matrices with Arduino

juuli 29th, 2014
by jaanus
Cheap HUB75 RGB matrix working

Cheap HUB75 RGB matrix working

Everyone likes LEDs. I like when I have a bunch of them. So one day I realised that I have about 15 big 32x16 RGB LED matrices in my lab. They are cheaper versions of Adafruit's led matrixes. Both matrices use standard HUB75 pinout. The pinout is same, LED count is the same, but display doesn't work - it is wired differently inside.

Driving matrices

Most simple way to do a led matrix is to drive low side columns with sinking driver chips and rows with high side mosfets. When you have bigger display - let's say 24 driver chips in total, then usually you will make multiple parallel lines of data to clock information faster.

HUB75

HUB75 is a standard interface to control matrices like that. It has binary inputs for mosfet control: A, B, C and D. So you can have up to 16 rows. Also, you have 6 data buses: R1, G1, B1, R2, G2, B2. Now, to control a matrix you have to know two things: how many virtual rows and columns does your matrix have and how are they mapped with reality.

Backside of my LED matrix, 24 drivers are visible.

Backside of my LED matrix, 24 drivers are visible.

Differences from device to device

The Adafruit matrix has 12 driver chips and 8 rows controlled by mosfets. Mine have 24 driver chips and 4 rows. Also, Adafruit's one seems to be mapped quite straightforward way. Mine in the other hand.. rows are separated to eight banks that are all in different directions. Still - no problem. Mark Laane, a programmer in my lab, sat down with the matrix and soon we had a working library. You can find it from here:

https://github.com/zidik/LedMatrix16x32-Alternative

Arduino Micro soldered to HUB75

Arduino Micro soldered to HUB75

Electrical wiring

I soldered my matrices directly to Arduino Micros. Since the pinout is slightly different from Uno, the connection diagram got hurt a bit. This library works with following connections:

HUB75 Connect to On Micro
R1 PB2 MOSI
G1 PB3 MISO
B1 PB4 8
GND GND
R2 PB5 9
G2 PB6 10
B2 PB7 11
GND GND
A A0
B A1
C A2
D GND
CLK A3
LAT A4
OE A5
GND GND

 

Posted in Small projects, Soft | Comments (0)

32 channel mains lamp controller

oktoober 19th, 2014
by jaanus
4 channel stackable thyristor board

4 channel stackable thyristor board

I needed a computer controllable 32 channel light dimmer for an art installation. After looking around a bit I found out that there isn't even a Arduino shield for the work. So I made a quick 4 channel stackable board to control lights.

The board uses SHARP thyristor based solid state relays to switch mains voltage. As normal with thyristors - all the outputs can be used as dimmers through zero-crossing detection.(Edit: It turns out since these have built in zero crossing detection, dimming is not possible) All outputs are able to handle 0.9 A / 200 W. We connected 40 W incandescent light bulbs to it but you can control whatever with it - lights, electronics, computers, motors etc.

The end device has Arduino as a controller, so all the lights can be switched from computer over USB. And since all the outputs are optically isolated from controller, the USB side is quite safe even in error situations. Also the Arduino can be reprogrammed for any preset pattern.

Get the controller source code from github: https://github.com/jaanuskalde/light-controller

Or buy it from my open source webshophttp://tech-thing.org/usb-controller-light-dimmer/

16 channels of mains switch

16 channels of mains switch

32 channel lamp dimmer overview

32 channel lamp dimmer overview

Back side of the device. USB and manual.

Back side of the device. USB and manual.

Posted in Small projects | Comments (2)

Multicode transmitter

mai 19th, 2014
by jaanus
Satel multicode transmitter

Satel multicode transmitter

I got my hands on a broken Satel OY multicode transmitter. It is an transmitter used to get information from remote sites - alarm codes, telemetry or sensor values. You can attache it to your pump or ground station and it sends a message up to 30 km if something is wrong. It puts up to 4 W of output power to VHF band 152 MHz in FSK modulation. As alarm systems go - it also had a place for backup battery.

This device is designed and produced in the end of nineties and it can be seen from the build. Old chips and packages.

The device itself is screwed in a thick aluminium box for weatherproofing, RF shielding and mechanical rigidity. Input power and signals come from DB15 connector and all go through low pass filters for protection. It has to survive the scariest test ever - the user! The brain of the thing is socketed Atmel TS87C51RB2 in a PLCC44 package. It is a device before flash memory - only single programmable!

Overview of transmitter

Overview of transmitter

From RF section we don't find fancy transceiver chips. Frequency synthesise is done by temperature controller temperature oscillator in a separate metal can. Modulating multicode is generated by Motorola MC14515 PLL frequency synthesizer. Bunch of analog RF circuitry filled by RF inductors does the modulation and matching. The output is amplified by BLT50 Power amplifier that is used out datasheet frequencies. Do your own datasheet - typical for RF power stuff. They don't use air core inductors, so they lose a bit of efficiency, but since it is externally powered they don't care. Also TLC542 ADC is used to get some feedback from RF front end.

Back side of the PCB

Back side of the PCB

Power amplifier and insides of a TCXO

Power amplifier and insides of a TCXO

Posted in RF, Teardowns and reviews | Comments (0)

Laserworld CS-500RGY

veebruar 28th, 2014
by jaanus
Laser projector, working

Laser projector, working

I got my hands on a Laserworld CS-500RGY laser projector. This is the smallest 500 mW one. It is a device that has three laser sources (red, red and green) and mirrors for moving laser pointer. It can be controlled by sound, DMX512 or ILDA interface. So, lets tear it down.

Case is really rugged and strong, made to last. Also has two fans for forced air cooling. Most of the insides is empty, they use the same chassis up to 2 W RGB projectors. Electronics is really modular and all through hole assembly. All what you would expect from low volume device and more than 10 year old company.

The laser assembly has two beam splitters that combine three laser sources into one. They two motors with feedback are used to move mirrors into correct angle.

Laserworld laser insides

Laserworld laser insides

Laser assembly, two small red lasers and one big green.

Laser assembly, two small red lasers and one big green.

Mirror assembly with two stepper motors.

Mirror assembly with two stepper motors.

Main processor with firmware sticker

Main processor with firmware sticker

Posted in Teardowns and reviews | Comments (1)

Contract engineering

veebruar 20th, 2014
by jaanus

I have done contract electrical engineering for ages. Previously mostly for university and friends, but as time went forward, more and more professionally for companies. As I also got my own lab and couple of employees - it was time to go official. So I got involved with couple of companies.

Tech-thing OÜ - electrical design and small scale manufacturing. We have capability to design and prototype wide area of devices - from small LED devices to big motor controllers and RF circuits.

Crystalspace OÜ - nanosatellite subsystems and components.  We specialize into making small satellite components, like power supplies, attitude determination and communication systems. Also mechanical components like frames and reaction wheels. And finally - whole small satellites.

Posted in Other | Comments (0)

Matching rf amplifier: Smith chart matching

jaanuar 23rd, 2014
by jaanus
linSmith with PI matching circuit

linSmith with PI matching circuit

I have to match 7.799 Ω+1.3158j to 50 Ω load with PI filter at 430 MHz. My advisor's advice - use pen and paper and Smith chart. But since I'm determined not to do maths on paper ever again (we have computing machines available now) then I started to search other ways out. So I read a tutorial on Impedance Matching and The Yin-Yang of Matching, really great stuff.

Then I found program called linSmith. Runs natively on linux, but requires compiling. User interface is quite good and no user manual is needed. I just typed in working frequency and starting complex impedance. Next I put in PI filter components with approximate values. It started showing all values on Smith chart. Little bit of playing around with sliders to adjust values. After couple of minutes I had values for my filter that matched impedance well and was made out of readily available components.

Next step is testing the calculated values on real circuit board. Real board and components have parasitic elements. The final values will be determined by trial and error, but the calculators give very good starting point.

Posted in RF | Comments (0)

MIMP, Advanced Design Studio, scikit-rf

november 5th, 2013
by jaanus

I was searching for a program to match RF circuits. I already calculated input complex impedance and choose pi filter as topology.

First I looked Motorola Impedance Matching Program. It is really old program, runs in Dosbox and is quite awful. User interface is manageable after reading the manual couple of times. Got the filter values from the program, but I'm not sure in these since I'm not sure I used it correctly. But in its free and cross platform so, why not use it.

I also tried Agilent Advanced Design Studio, but yea, it is meant for full time RF engineers. It looks like it can do everything. Usability is almost okay, feels inconvenient like ltspice.

Next I tried to simulate the circuit with scikit-rf. Importing the network worked fine, but the easy part ended there. To make components I first needed to make Media. There was no lumped element Media, so I took the one easiest to use - Freespace. Also the connections don't sound really correct.

#Program accepts one argument - C1 value in picoFarads of PI filter. 
#It outputs transistor output impedance (calculated from amp.s1p file) 
#and a graph showing preferred PI filter component values.
import matplotlib.pyplot as plt
from pylab import *
plt.ion()

import skrf as rf
rf.pico = 1e-12

import sys

#amp that we are matching only S22
amp = rf.Network('amp.s1p')

print amp.z

#we need media to make components. weird
media = rf.media.Freespace(amp.frequency)

def get_db(C1, L, C2):
   #pi filter begin
   C1 = media.shunt_capacitor(C1*rf.pico);
   L = media.inductor(L*rf.nano)
   C2 = media.shunt_capacitor(C2*rf.pico);

   filter = rf.connect(rf.connect(rf.connect(amp,0,C1,0),0,L,0),0,C2,0)
   return filter.s_mag[0][0][0]

print get_db(10,22,7)

out = []
for L in range(1,15*3,3):
   out.append([])
   for C2 in range(1,15*2,2):
      out[-1].append(get_db(int(sys.argv[1]),L,C2))

#raw_input()
#print out
figure()
title('Pi matching network, C1 = '+sys.argv[1]+' pF')
imshow(out)
xlabel('C2 value [pF]')
ylabel('L value [nH]')
xticks(range(15), range(1,15*2,2))
yticks(range(15), range(1,15*3,3))
cbar = colorbar()
cbar.set_label('Return Loss Magnitude')
grid(False)

show()

raw_input()
PI filter values in respect of output reflected power.

PI filter values in respect of output reflected power.

And this program provides graph you can see on the right. Really nice graph what in theory should show right values. I like how I can look at the graph and pick values that exists in the shop and see how effective filter would be. But again, I can't verify these values on other tools so there is probably small miscalculation in my code.

Posted in Teardowns and reviews | Comments (2)

Matching rf amplifier: calculating complex impedance

jaanuar 23rd, 2014
by jaanus

I'm building a small 430 MHz  1 W RF amplifier to get some practical knowledge about RF design. Choosing components and making the PCBs was walk in the park. But suddenly my instructor said that I have to match my amplifier with next stage.  It is weird, because I thought that RF amplifier meant that output would be 50 Ω, but no, it is something totally random.

So, my amplifier TQP7M9105 has page with S parameters. S parameters are parameters that describe RF components working in a 50 Ω environment. In our case S22 is what we want. 22 mean that it is second port reflections to second port aka output information. S22 at 400 MHz is -2.73 dB 176.91 degrees. This is - connecting output directly to 50 Ω output you get attenuation of 2.73 dB and phase shift of 176.91.

To calculate complex output impedance I used scikit-rf python library, because I couldn't find any online calculators doing the same job. Input was fed from  Touchstone SnP Format file type, because this was the only way I could think of to convert dB form to rectangular form:

# MHz S DB R50
400 -2.73 176.91

And code itself was:

import skrf as rf
amp = rf.Network('amp.s1p')
print amp.z

So, my amplifier output impedance @400 MHz should be 7.799Ω+1.3158j. Quick check from mismatch calculator confirmed my results. Next I used PI-match impedance matching calculator to calculate necessary values. Got some answers, probably will use other methods to check if they are correct.

Posted in RF | Comments (1)

Buck-boost converter from LT3791-1

oktoober 22nd, 2013
by jaanus
Finished prototype, some mosfets and big inductor.

Finished prototype, some mosfets and big inductor.

I'm building quite high power (for me) buck-boost converter for a friend. It takes in 12-45 V and has to output regulated 24 V. Total output power has to be more than 300 W. I don't understand switching regulators well enough to build more than 100 W regulators from 555 timer (that is basically how your computer power supply is built). Just too much phase shifting and output oscillations and whatever else to take into account. You know, the things you learn in electronics classes (which there was none in my school).

LT3791-1 in the middle of a debugging session.

LT3791-1 in the middle of a debugging session.

So I took the highest power buck-boost controller I could find - LT3791-1. It satisfied all my specifications so I calculated what parts would I need to make a 300 W board out of it. After ordering stuff and soldering it together it looked awesome. But after some playing around I couldn't get it to boost more than 100W, buck worked well but boost didn't. After lots of debugging and bunch of fried chips I finally figured out that the MOSFET drivers are too weak. My big and high power mosfets didn't even get warm at 300W output, but the chips internal voltage regulator fried all the time.

So, lessons learned from high power:

  • Every watt adds problems to MOSFET driving
  • Don't over specify parts three times

Next prototypes will be smaller and there will be several of them in parallel. Maybe some pictures soon.

Posted in Small projects | Comments (8)

Aalto-1 photos

september 27th, 2013
by jaanus

I have been visiting finnish Aalto-1 satellite project a couple of times. I am building half of one of their experiments - motor control board for electric plasma brake. Took bunch of cool pictures of their technology. Enjoy.

Mock-up satellite for exhibitions. Really good for overview.

Mock-up satellite for exhibitions. Really good for overview.

LM75 temperature sensor on the outside of the satellite.

LM75 temperature sensor on the outside of the satellite.

Solar cells are soldered to the PCB, it gave some trouble in thermal vacuum tests.

Solar cells are soldered to the PCB, it gave some trouble in thermal vacuum tests.

Prototype of Aalto-1 on board computer. Two cold redundant AT91RM9200 ARM processors running linux. And small MSP420 FRAM microcontroller that switches between them.

Prototype of Aalto-1 on board computer. Two cold redundant AT91RM9200 ARM processors running linux. And small MSP420 FRAM microcontroller that switches between them.

Bottom of on-board computer. Battery for real time clock and some memory.

Bottom of on-board computer. Battery for real time clock and some memory.

S-band downlink and GPS system. On the bottom there are: S-band tranciever, distributed element filters, power ampliffier and some more filters. On the top there is GPS module with antenna connector.

S-band downlink and GPS system. On the bottom there are: S-band tranciever, distributed element filters, power ampliffier and some more filters. On the top there is GPS module with antenna connector.

Local flatsat, really useful for satellite testing if it works.

Local flatsat, really useful for satellite testing if it works.

Open antenna setup. It consists of two 70cm dipole antennas. Elements are connected with UMC connectors and antenna block with MCX.

Open antenna setup. It consists of two 70cm dipole antennas. Elements are connected with UMC connectors and antenna block with MCX.

Antenna relase mechanism. Resistors for burning the wire and switches to detect the release.

Antenna relase mechanism. Resistors for burning the wire and switches to detect the release.

What I want to find from every lab: bunch of multimeters on a stack of documentation.

What I want to find from every lab: bunch of multimeters on a stack of documentation.

Prototype electrical power system for next satellite. Looks like classical EagleCAD work.

Prototype electrical power system for next satellite. Looks like classical EagleCAD work.

Another power system prototype.

Another power system prototype.

The side of the satellite. Solar cells, connecting PCB and strong machined side panel.

The side of the satellite. Solar cells, connecting PCB and strong machined side panel.

Posted in Space | Comments (0)

New lab

september 12th, 2013
by jaanus
Old lab in my room.

Old lab in my room.

My old lab was in the corner of my dorm room and as projects proceeded I needed a bigger lab. So, I got one. I teamed up with couple of my friends and we got 80m2 of space in nearly industrial building. It is nice to have room big enough to have 7m Yagi antenna indoors. In the same room there is EDM OÜ making small CNC machines and soon, couple of more startups.

New lab area, with more room.

New lab area, with more room.

Mechanics room with some machines and antenna.

Mechanics room with some machines and antenna.

Posted in Small projects | Comments (2)

Bicolor led cube

august 29th, 2013
by jaanus
Bicolor led cube, displaying red characters.

Bicolor led cube, displaying red characters.

I needed a bicolor LED cube, so I designed one. One coloured cubes are useful only as toys so bicolor one seemed like the easiest to make. I used Atmega8u2 to control two TLC5926 and high side switching was done with four small mosfets. As a bonus feature I used NCP3170 to convert USB 5V to 2.2V more suitable for red and green LEDs. Using a switching regulator let me use power from USB more efficiently.

Bottom side of LED controller board.

Bottom side of LED controller board.

My second led cube was much more ambitious - 6x6x4 RGB led cube. I planned to use one big Atmaga and charlieplex all the pins. I did the easy part - calculations, designing the system, routed and soldered the circuit board. Then I faced with the killer part - soldering 144 small surface mount three color LEDs to thin wires to form a cube. I tried couple of different racks but it was too time consuming to do even one. Some day when I think of a better way I will build a dozen, but for now it goes on my Out of Development wall.

LED cube controller.

LED cube controller.

Posted in Small projects | Comments (0)

AMSAT-UK Colloquium

august 5th, 2013
by jaanus
High end camera system for cubesat. Three temperature compensated cameras, beefy FPGA, radiation sensors and bunch of flex-rigid cabling.

High end camera system for cubesat. Three temperature compensated cameras, beefy FPGA, radiation sensors and bunch of flex-rigid cabling.

So I got the opportunity to visit AMSAT-UK  Colloquium. What is that anyway? Well - Radio Amateur Satellite Corporation UK edition's meetup.

ISIS VHF/UHF radio system. Notice the weird soldering of crystals and resonators.

ISIS VHF/UHF radio system. Notice the weird soldering of crystals and resonators.

On the first day there was a bring your own board meetup. So we took about all of the ESTCube-1 PCB and threw them on the table and went off to talk with other people. It was really fun and I took a lot of pictures of other people's work. From that I learned that many people have the same problems as us. System engineering problems, internal communication protocols and so on.

There was a bunch of talks about well, amateur radio satellites. European Space Agency guy was talking about their workflow (which made me doubt in them a bit more) and then about their projects (which made me to like them again). QB50 guys were talking about behind the scenes and future of this project. I got more confirmation that system engineering is awesomely hard. So I want to do it even more.

We got a tour in the Surrey University space center and Surrey Satellite Technology LTD headquaters and could see in their cleanrooms. They had more cleanroom soldering places as whole Tartu has normal ones..

But most importanly - I meet up with a lot of cool people. If everything goes well then I will be involved in some ESA projects soon.

NB. And I got to see the PCBSat, wee!

Pretty and small GPS for space. Surrey SGR-05. Normal GPS algorithms are made for using ON the planet so you need you own. Also if you go further than GPS satellites they you can't hear them very well. Antennas are directional towards earth.

Pretty and small GPS for space. Surrey SGR-05. Normal GPS algorithms are made for using ON the planet so you need you own. Also if you go further than GPS satellites they you can't hear them very well. Antennas are directional towards earth.

PCBSat! 1/4 U Cubesat. The cutest thing ever!

PCBSat! 1/4 U Cubesat. The cutest thing ever!

PCBSat internals. Not so impressive but basically as good as half of cubesats.

PCBSat internals. Not so impressive but basically as good as half of cubesats.

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