I ordered a single panel as a test for the production version of the plant watering sensor and I got astonishing perfect panels from Eurocircuits.
Even I only ordered just one, I got three perfect panels in gold. Thank you very much Eurocircuits! As you can see from the photos, the quality of the panels is just amazing.
This panels use the Eurocircuits registration system. This is a own set of rules for the registration holes around of the panel. Using these registration holes, I can easily align the stencil and the board on a special tool they produce. I will tell more about that in one of the next parts of the series “How to design a cheap plant watering sensor” (Read Part 1, 2, 3, 4, 5)
If you have questions, miss some information or just have any feedback, feel free to add a comment below.
Update: Weller solved the problems I describe in this article with a new design of the retainer. This new retainer solves all the problems described in this article. The new retainer looks very different and uses a spring to pull the tip to the heating element.
A little bit more than a half year ago I bough a Weller WT solder station. This solder station has a very smart design and there are many features I like.
The solder pencil is very small, but has exactly the right weight and grip to solder for a long time without fatigue.
The cable between the station and the pencil is very flexible, soft and never gets tangled magically.
The tip heats up to working temperature in seconds.
After a programmed time, the station goes into power saving mode and automatically wakes up as soon you touch the solder pencil again.
It has a large nice display, just showing the info you actually like to know.
Even digital, temperature can be quickly and precisely changed.
The solder pencil is very modular, you can actually have multiple heat elements with different tips and change them in the middle of the work.
The tips are small and relatively cheap, but from a high quality.
The stand is heavy and does not slide away. You can switch between brass wool and a sponge if you like.
I am a machine engineer and very used to work with CAD software. The abbreviation CAD stands for Computer Aided Design. I personally think, Autodesk Eagle fails with the ‘A’, because often it does not give you any aid. On the contrary it often puts a spoke in the wheel and makes your life horrible.
Please do not get me wrong, there are many aspects I like and the alternatives I know have other issues. I would really like to work with Altium Designer, but a license is way to expensive for me as hobbyist. There is also KiCAD, a very promising program. I will try to do a whole project design in this software soon, to see where the strengths and weaknesses are.
I hope the Eagle developers will be able to add the described features to the software. They develop Eagle using C++ and the Qt framework – I personally really like this language and framework combination and use it for most of my own software.
1. Inadequate Layer Handling
Even if you only work with a two layer board, the board display quickly gets crowded and it is very hard to see all details.
It is not only the visual representation, as soon objects are close, selecting a specific one gets really hard. In some locations, you always have to cycle through many objects, until you find the right one. This is slowing down your work and is really annoying.
Hide some of the layers is the solution for this, but you have to do this either via text commands, or create many own keyboard shortcuts to work efficient. Just for the simple action to only show the top layer, you have to enter display none top and shortly after this display last to restore the previous view. There is a panel, where you can do this actions graphically, but this is a modal dialog and blocks further user input – it is useless for efficient work.
For a software, where layers play an such important role, the layer handling is inadequate. Every modern vector drawing program already demonstrates, how an efficient layer handling can be implemented.
There should be a permanent visible panel, docked in the window, where the list of all layers is visible:
It should be possible so view only a single layer and restore the previous view easily.
A special combination of layers should be save- and loadable.
Layer presets should be accessible via keyboard shortcut.
All layer should be made visible with one click.
There should be a default view to restore at any time.
The panel should be easily hidden and shown with a keyboard shortcut.
Another important missing feature is locking. Each layer should be lockable, so no objects on this layer can be selected or modified.
Each layer should be lockable.
All layers except one, should be easily lockable and the previous state restored easily.
There should be an option to allow modification of attached objects, even if the layer of these is locked.
I just finished a small series of the PissOff project. After all work done, I probably would use a stencil and solder paste next time.
For this series I used a slightly larger speaker to improve the loudness and sound quality. Tried some different ones, but the really good ones do not fit on the back of the project anymore.
While soldering all these boards, I found out the contacts of the SD card holder do not always easily connect to the PCB. If the SD card is not working, resoldering these solved problems for two boards. Also in one case, flux came into the trimmer, there was no contact anymore and no sound output.
I made a short video how I solder the Boldport project “Touchy”. It is a SMD project with a quite difficult to solder chip. For the first half of the assembly, I did not notice that the solder tip was no screwed tight, so the heating of the tip was not optimal.
Click the link below for the same video on YouTube in a better quality:
If you already saw the soldering video, here two photos of the result.
To get this result, I was inspired by the way Saar from Boldport was soldering his own projects, I adapted his technique.
After initial soldering, I flush cut carefully the wire as close as possible to the board. Cutting off any solder with the wire to make it flat.
Next I add more solder to the point until it forms a small round dome.
On the component side I add solder if necessary to fill the hole and make a smooth transition from the hole to the wire.
For this photos I use solder with lead – this is a huge exception. It is the only way to get this shiny domes. Normally I work with lead free components and solder according to ROHS.
I recently ordered a set of “PCBite”. These are special PCB holder as shown in the images in this post. To solder components into PCB I sometimes used one of this many “helping hands” products with two clamps, but they are no real use in most cases.
PCBite seems to solve some of the problems very well. You get a metal plate with a mirror finish and four of this cylinders which have a very strong magnet in the base. The middle part of the cylinder with the grip on is can be moved down and the PCB fastened that way. It is very solid and two would be enough to hold the PCB easily.
The mirror finish makes the bottom side of the PCB easily visible so you can solder on the top side and keep the component in view.
You can get you own set for $79 here, this includes free shipping. The quality of this PCB holder is outstanding. If you look at the close up photo, you see the perfection how this tool was made. I can really recommend this PCB holder.
Currently I am working on the final assembly of the Outmoded Sequencer, it looks very promising. There will soon be an update with all details about the final device.
As expected, there were many things that went wrong in the process from the prototype to the first PCB version of the project. I would like to share them here, maybe it will prevent similar mistakes in one of your projects.
Wrong Values
While drawing the circuit diagram, I copied all values from the components into this document. But later, I experimented with the prototype and changed components – but forgot to update the values in the circuit diagram.
When I soldered the components onto the PCB, I just read the values from the diagram and did not cross check them with the prototype. I soldered the wrong capacitor on the board and it took a while to find the problem. It was hard to remove the wrong component and replace it with the correct one.
How to fix later: If the shape of the components match, you can easily unsolder the wrong component and use the correct one. But often you have to destroy the wrong component to be able to unsolder it.
How to avoid: This is very easy to avoid and there are two safe strategies. First I keep a sheet with the printed circuit diagram beside the prototype. So I can easily note any changes I do and update the diagram later. Second, before I order a new PCB, I check all values in the diagram with the prototype.
Not Connected Copper Pour
I created a copper pour on both sides of the PCB, but somehow I did not connect the pour on the bottom side with GND. This is not easily visible, because usually while drawing routes you keep your board free from the pours and just add them for the final touches.
How to fix later: You can not fix this entirely, but you can prevent the worst. Just scratch off the solder mask from the largest pours and connect them to ground with a small wire.
How to avoid: If you do the final checks, check each layer individually. So you will spot this problem immediately.
Today I shot a short demonstration video, which shows all 50 modes of the table light visually. The video can not replace a real table lamp, but you will get a first impression. And you can obviously implement your own colours and effects with own code.
