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Showing posts from 2015

Touch sensor, aanraaksensor, capacitief, voor attractiepark (video)

Voor een bevriende ontwerper van waterattracties een proof of concept.

Het betaat uit 2 pads van een AED, een chip met 2 oscillatoren, waarvan 1 beinvloed wordt door de pads.

Op youtube fimpje gezet, 1 foto 1000 woorden, 1 filmpje ook zoiets. Dat scheelt weer veel typewerk.

tot laters.
Heb je zoiets nodig, neem contact op.

Met gemak door 8 mm acryl isolatie, zal worden gebruikt met glasvezel/epoxy.
Schakelt 1 contact, optisch gescheiden, voor bediening van klep of pomp in waterattractie.

EMC/EMI in een auto of vliegtuig

In response op een discussie met een aantal "deskundigen" op het internet heb ik een filmpje gemaakt dat laat zien dat het gebruik van zenders, zelfs als zijn ze van laag vermogen, in voertuigen zoals auto's en vliegtuigen niet zonder risico is.

Ik wordt altijd een beetje kwaad als ik mensen dingen hoor verkondigen met een zekerheid die grenst aan religeuze overtuiging en fanatisme over een onderwerp waar ze helemaal niks vanaf weten.

Zo'n onderwerp is het effect van elektrische of magnetische velden op elektronische apparaten.

Er zijn mensen (heel veel mensen) die beweren dat het gebruik van elektronische apparatuur en mobiele telefoons absoluut geen effect heeft op een auto of vliegtuig.

De argumenten zijn dan :

* "ik zet gewoon mijn telefoon aan, en we zijn niet neergestort"
* "ze willen gewoon hun eigen telefoondiensten verkopen"
* "die vliegtuigen hebben heel goede afscherming, dus dat maakt niks uit"
* "Ik ken iemand die er ve…

CNC milling OnShape design 20 mm aluminium

A few days ago I started playing with OnShape, an online design program. It can do a lot of things and I am very impressed by it. Check it out at
I designed a mounting bracket for my camera microscope (which needs to mount on my spindle motor)

In 3D it looks like this 

And after exporting the contour as a DXF file I milled it on my CNC machine. I used a 4 mm 2 flute end mill, at 20000 rpm. The mill had to stick out quite a lot, so I have some shatter markings on the surface, but it worked, milling 20 mm thick aluminium.
The results are here.

Impressive right ?
Until next time, Greetings from Holland ;-)

Laptop repair (MSI 1035 OEM) saved money again

Today I repaired my laptop.
It was not working anymore, completely dead. Here is a link to the manufacturer :
It is an old one, it does not support Virtualbox, but runs Debian just fine. I like it because it has a 17" screen, nice to work in bed, full size keyboard too.
Searching for problems without any schematic is just gambling so I postponed it. I found a YouTube channel by Louis Rossmann who repairs laptops, and he got some schematics from a website :
I ordered my schematics for about 10 euro. I got 57 pages of PDF.
I had to take apart the whole laptop to get near the actual hardware.
I took my time, did not break any plastic tabs off.. And after what seemed like an hour I was where I needed to be.
I started at the beginning, the power input and verified it. 19.14 volts. At the end of the cable, without load 18 volts... weird stuff. I look…

Why? : Because we can...

Today I repaired a parking sign.


Because I need to have an excuse to use my CNC milling machine, that is why!

I drew the sign with Q-Cad professional ( and imported it into USBCNC.
I used a 2 flute 4 millimeter end-mill and created a couple of P characters.

Do you want to make one too : here is the DXF file, have fun.

Deja Vu? (no picture on the screen) Bad caps again, and again Samsung.

Today I repaired a Samsung TV in just a few minutes. A friend walks in and says : My Samsung TV is ticking.. Red light blinking on/off... It is about 6 years old... What could it be?
I just say : "Ah bad caps again?"
Reply : "Do you really thinks so?"
Let's fix this puppy a.s.a.p so you can watch TV again.
So I take my screw driver and go with him to take a look at the TV. Indeed, it is trying to start but fails etc. tick tick tick blink blink blink...
1) remove power cord 2) take off back cover 3) look around 4) Notice caps with round caps in PSU???

Of course there are, 2 bad capacitors, 10 Volt 1000uF close to a thermal aluminium block. Alright, here they are... I say..
Exclamation : "Bad caps again? Can they not make anything anymore without bad capacitors, I bet most of these TV's get dumped in the trash for this"
And that is probably true, a bad capacitor costing 20 cent will make your TV worthless. And please note this is not a low end TV, t…

RX TX of a USART is easy (right?)

Today I figured it out.
What did you figure out, I hear you say...

I finally resolved a problem with a USART on a STM32F407 board, that was easy to spot if I had just looked closely. I just lost a day in trying to find the fault.

I am working with this board made by Olimex (

And connected it using ST-Link interface to my PC.

I connected the SWD pins to the JTAG connector of the Olimex

SWD-pin-1 ------ JTAG-pin-1 (VCC)
SWD-pin-2 ------ JTAG-pin-9 (TCK)
SWD-pin-3 ------ JTAG-pin-4,6,8 (GND) SWD-pin-4 ------ JTAG-pin-7 (TMS) SWD-pin-5 ------ JTAG-pin-15 (TRST) SWD-pin-6 ------ JTAG-pin-13 (TDO)

I connected the serial port (USART6 is pins 3 and 4 of UEXT) of the Olimex to the TX/RX lines of the ST-link (see the green circle)

Then I wrote a program and tested it.
I made sure the PLL of the STM32F407 was running, configured all the needed files.

defined the target cpu in stm32f4xx.h (STM32F40_41xxx)defined the real crysta…

A new generator of PWM controller for AutoJet

Currently I am working on an alternative controller for AutoJet Technologies Spray controller made by Spray systems Inc.

I have been working on a more advanced and microprocessor controlled controller, it is intended to be used where the Model 1008 (AutoJet PWM driver modules, aka CP-PMDCT1008-XX) are not advanced enough or easy enough to install and set up.

The 1008-AutoJet device is a pure analog box, it needs to be programmed with potentionmeter/trimmer inside the device and can be controlled externally using industry standard 0..20mA current loop to control frequency of pulses.

The typical application I am looking at is the airless deposition of oils or emulsions used in the production of concrete products.

The oils or emulsions are used as releasing agents with high viscosity, mould release agents designed for the production of expanded concrete blocks. 
Deposition with air-driven nozzles leads to inaccurate placements of d…

Failed to load session "gnome" and how to fix it on Ubuntu

It has been far too long since I wrote something on my blog.
I have been writing on another site : about my CNC machine, and about the mcHF transceiver I am building.

Today I ran into a little problem after updating some packages on my Ubuntu 12.10 VM. (I know this is very old, but I have no choice since a vendor supplied a gcc/uclib toolchain for a specific product exactly on this version of Linux)

However, my X did not start anymore, I got "Failed to load session gnome".

After some digging I realized what had happened, the default X session was set to gnome (which is not really installed) instead of my normal XFCE4 session.

If you know what the problem is, the fix is easy :

$ sudo update-alternatives --config x-session-manager

Then select the correct session manager.

I hope this helps someone from having to search a long time.
Until next time.

Exploding CAPS again, brand new CNC driver board goes BANG. (but will be replaced)

I have been working on my CNC milling machine and tested the new stepper motor controllers last Friday 13th.

Brand new controller, power supply made of a large toroidal transformer, large diode bridge and lots of parallel capacitors made a very strong 42 volt.

After the smoke cleared... I investigated the source of the problem. This was not a fault I made in wiring, nope...

The exploded capacitors were 220uF/16 Volt types parallel to the power supply of 42 volt...

Not a real surprise that they did not last 2 seconds.
I do not think it is very hard to build a good CNC stepper board, but some engineers or buying departments still struggle with the basics like capacitor voltage specification.

After removing the exploded capacitors we managed to get the motor controller working without problems (without the caps) The CNC machine now moves all Axis fine, runs smooth in…

DDS UDB120x(s) serial protocol reverse engineering

I got a DDS with a serial interface

You can now control the device over a serial/USB port if you want.
Use my code, original research.