Scenes from the cutting room

Today was a day for more lasercutting. 16 MDF panels in total. When i got home i couldn’t wait to see if my calculations were correct. Other than a few minor errors it wasn’t that bad at all!

It looks all crooked on the pics but that is because they are very very roughly screwed in place. When they all fit, the entire thing needs sanding and paint.

image image  image

Console woes

Decided i needed more switches. More switches means more panels. More panels require console. See pics for progress.


Reading the not so smart meter

Today I completed another small project. I’ve got this ‘smart meter’ in my house. The smart bit is that automatically sends off the meter data to the network provider. But I can not see the actual power usage from inside my apartment.

My meter has an infrared LED interface (right next to the meter above 1000 imp / kWh), which gives a pulse for every kWh consumed. By measuring the time between pulses and to count I’m on a current consumption in watts (3.6 / pulse duration to be exact).

I already had a sensor network running based on my previous Simplyduino project, so the addition of a new node was a quick job.

The graph shows that it works well. I still can not explain all the peaks, but the high consumption (800W) between 10:30 and 16:00 is my electrical water boiler.  The other major consumers are the refrigerator, the coffee and tea (for short peaks).

Measuring is knowing!

IR sensor diagram (led1 not used for now).



Closeup of the meter



Sensorium graph:


Gathering of Tweakers nomination

Hi guys!

I’ve been invited by the guys from to do a video interview on my chair build! Woohoo.


HT16K33 breakout board

In line with my previous board i’ve designed a custom breakout board for the HT16K33. Much inspired (cough) by Adafruit’s break out board, this design allows for oriented connectors and a I2C passthrough chainability. As an added benefit i have added mounting holes with the same dimension as my controller PCB so they can site next to eachother.

The HT16K33 is a very nice led driver chip that allows 128 individually addressable leds on a single I2C ID. These leds aren’t individually adjustable in brightness like the MCP7219 but for me that isn’t a requirement.

The board is primarily used to drive the throttle and joystick led effects. Currently it is a little mess with all the wires sticking out.

I just sent it off to the PCB maker, I’m guessing i’ll find a design flaw within the next 24 hours.



UPDATE: The PCB’s have arrived. You can tell they came from the other side of the planet because everything is upside down (bading tssss)


Updated rudder control

Redesigning the joystick and throttle made them feel much more solid. In fact, they became that much ‘more solid’ that the old rudder control actually started to feel flimsy. So I tackled that one too.

Not much is changed from the previous setup. Most of the changes we basic ‘improvement’ steps. Here they are:

  • Main bearings changed from M4 to M5 width. Bigger bolts and bigger bearings means stronger bolts and bearings.
  • Ditched the old MDF panels and swapped them for black solid 5mm acryl
  • Hall effect sensor parts reprinted with PETG for additional strength and quality.
  • TODO: Recut the (white) mounting plate in black.

So, black it is. The A1302 Hall Effect sensor was already in the old setup so I just had to reassemble everything and perform a small calibration to get it working in the simpit.

IMG_2945 IMG_2951

Updated 3D-printed gimbal and throttle design

Here’s version 2 of my joystick mechanical bits. Improvements:

  • Metal control stick
  • Hall Effect sensors
  • Ball bearings
  • PETG filament
  • Adjustable throttle resistance

The metal pipe is what caused the new iteration. Not only is it much more solid, but because the wall of the pipe is much thinner without a change to the outside diameter means more wires can go through.

The change to A1302 Linear Hall Effect sensor was a logic move after the use of the same sensor in the foot controller proved very reliable.

Also I move from 3Dprinting with PLA to PETG. My Vertex K8400 give much stronger and consistent parts now.

With the use of ball bearings everything feels solid and absolutely free of any kind of play.

Gimbal_v2_explode Throttle_v2


IMG_2708 IMG_2928

Deck the Hall Effect Sensors with boughs of holly

I keep forgetting how to properly orientate the magnets for my the hall effect sensors. Courtesy of Allegro (the maker of these fine sensors) I copy the significant bit of their application guide.


Operating Mode Enhancements: Compound Magnets


Because the active area of a Hall switch is close to the branded face of the package, it is usually operated by approaching this face with a magnetic south pole. It is also possible to operate a Hall switch by applying a magnetic north pole to the back side of the package. While a north pole alone is seldom used, the push-pull configuration (simultaneous application of a south pole to the branded side and a north pole to the back side) can give much greater field strengths than are possible with any single magnet (see figure 43). Perhaps more important, push-pull arrangements are quite insensitive to lateral motion and are worth considering if a loosely fitting mechanism is involved.

figure 43Figure 43. Examples of compound magnet configurations (either the Hall device or the magnet assembly can be stationary), with a south pole toward the branded face and a north pole toward the back side: (left) push-pull head-on and (right) push-pull slide-by 


Figure 44 shows the flux-density curve for an actual push-pull slide-by configuration that achieves a magnetic slope of about 315 G/mm.

figure 44Figure 44. Example of magnetic flux characteristic in push-pull slide-by magnet configuration 



Another possibility, a bipolar field with a fairly steep slope (which also is linear), can be created by using a push-push configuration in the head-on mode (see figure 45).

figure 45 Figure 45. Example of a push-push head-on compound magnet configuration (either the Hall device or the magnet assembly can be stationary), with south poles toward both the branded face and the back side 


In the push-push, head-on mode configuration shown in figure 45, the magnetic fields cancel each other when the mechanism is centered, giving zero flux density at that position. Figure 46 shows the flux-density plot of such a configuration. The curve is linear and moderately steep at better than 315 G/mm. The mechanism is fairly insensitive to lateral motion.

figure 46Figure 46. Example of push-push head-on mode magnet configuration, in which the fields cancel in the middle of the travel range

back up

My internet provider had made a boo-boo and we were offline for maybe 90 minutes. All is well now, carry on.

Handle USB Host Suspend/Wake on Arduino Sketch

The lighting plan for my game seat uses a lot of LEDs driving by a few Arduino’s,  and I thought it would be nice to shut down the LEDs when the host PC shuts down.

It turns out the current USB Device implementation of Arduino does not implement such a feature so I decided to hook into the USBCore.cpp file with a few simple statements.

I have submitted the change as a pull request on the Arduino github. Find the patch here: