Sonntag, 20. August 2017

Hydroponic Veggies Part 3 -- Calibrating the PH probe

Step 1: Buy calibrated PH buffer solution (at least 2 different reference points are needed)

Step 2: Dip the probe in, log the raw values

Step 3: Install Python and calculate correction values

Here's the Jupyter Notebook I used for that purpose


Samstag, 22. Juli 2017

Hydroponic Veggies Part 2 -- The water level sensor

The initial idea was to stick a VL53L0X TOF distance sensor to the reservoir lid and get the water level from there.
Didn't work out. Not enough light reflected from the water surface lead to super flaky readings. What did work out in the end is this ...

Donnerstag, 6. Juli 2017

Fan-Tas-Tic Pinball, Part 7, Back to a LED - display!

The original Fan-Tas-Tic machine had a mechanical roulette wheel assembly, visible through a window in the middle of the playing field. For some time now I had it replaced with a 1280x720 LCD panel.


However, I'm not completely happy with this configuration and recently decided, the LCD panel has to go! 

Montag, 3. Juli 2017

Hydroponic Veggies

The goal is to grow tomatoes, chilis, carrots, lettuce and spinach on my balcony. It shall be hydroponic and as much automated as possible. Here's my setup so far ...

Plumbing and Dutch-buckets

No rocket since here. It's all made from 1/2 inch PCV pipe and fittings from the hardware store. The buckets were done according to these excellent instructions by mhpgardener. As I wanted the setup to be removable, I didn't use any glue. To achieve a good seal anyway, I used a bit of silicone grease on all fittings. So far it holds up fine.


Sonntag, 1. Mai 2016

Fan-Tas-Tic Pinball, Part 6, EMI trouble!

This is going to be a little story about electromagnetic interference (EMI). The good thing is: there will be a happy end :)

Having installed all the WS2811 LEDs, I decided to play a quick game to see if everything is still working. It was quite surprising to see the LEDs flicker like a Christmas tree, even though they should have been dark. This happened everytime the flipper coils actuated. Clearly there was some kind of EMI problem, inducing noise on the data line of the LEDs.

A quick scope measurement on the solenoids revealed the issue:

Samstag, 16. April 2016

Fan-Tas-Tic Pinball, Part 5

Adding some LEDs

I did a quick test with the WS2811 LED strand and I'm quite satisfied with the results. They are slightly brighter then the original bulbs, consume far less power and hence don't get hot. Especially under the white playfield inserts, the RGB colors look fantastic. The red inserts filter out all the other colors, so it only makes sense to have these LEDs configured for red only -- but that's not a big problem, considering how cheap those LED strands are.

I started to work on a platform driver for the Mission Pinball Framework v30. There is some basic functionality already -- but still some bugs need to be resolved.

Donnerstag, 3. März 2016

Fan-Tas-Tic Pinball, Part 4

 Rewiring the switches

There are around 40 switches on the playing field which were originally wired in a point to point fashion -- the cable management was quite impressive.

With the new electronics, switches are arranged in a 8 x 8 matrix. The row and column wires are tied together in two strands, which are routed in a serpentine fashion below the playing field. Finding a good way to keep the wires in order and organized took some time.

Some pics of the cabling `making-of` ...


The flipper buttons on the cabinet and the tilt switch (lead blob on a pendulum) was wired to a I2C port extender. The shielded white cable for the I2C is visible in the last picture.


The initial test look promising. The Fan-Tas-Tic controller scans the switch matrix and reports input changes to the PC.