Tag Archives: pcb

Good Quality Boards from PCBWay

Recently I received boards for a sensor array from PCBWay. This boards were made in a very good quality considering the low price level.

I really like the green solder mask they use, it creates a nice optical effect shifting the green colour towards yellow somehow. The solder mask produces a very nice contrast between the copper and non-copper areas, easy to see all traces.

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The small traces on this board have a width of 0.2mm with an insulation of 0.3mm. It is a lead free HAL which is nice and flat.

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Production time was two days (over the weekend) and shipping using DHL took four days.

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Routing of the boards is nice and smooth, there are no traces of tabs left on the boards.

All boards will be connected with a kind of bus in a circle arrangement as shown in the title image and the image below. There is an address selector on each board, to assign each sensor board an unique address.

By splitting the design of the sensor array into five equal boards, I could save a huge amount of production costs. Producing 10 of the shown boards, lead free HAL, with a production time of 2-3 days was just $19.

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If you have questions, miss some information or just have any feedback, feel free to add a comment below.

Have fun!

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Boards in Good Quality from SeeedStudio Fusion

SeedStudio offered me a coupon to evaluate their PCB service “Fusion“. I am currently working on a new project, so I gave this service a try. I used the following options ordering the two boards:

PCB Dimensions 68mm*108mm
Impedance Control No
Surface Finish HASL Lead Free
Minimum Solder Mask Dam 0.4mm↑
Copper Weight 1oz.
Plated Half-holes / Castellated Holes No
Minimum Drill Hole Size 0.3mm
PCB Color Blue
Base Material FR-4 TG130
No. of Layers 2 layers
PCB Quantity 5
Blind or Buried Vias No
PCB Thickness 1.6
Trace Width / Spacing 6/6 mil

I payed $27.40 for five boards with the option shown above and there were additional $20 shipping costs.

My board design has a very low quality class B4: Minimum drill size is 0.35mm, minimum trace size and spacing is 0.2mm.

Ordering and Shipping

The order process was very simple. The website provides an assistant with all possible options and calculates a quote in real time. I just noticed these minor things:

  • The shipping cost is not displayed in this quote.
  • The dimensions were not correctly extracted from my Gerber files.

The production of the boards and the shipping was quite fast, the whole process only took 10 days until the packet with the boards arrived.

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The boards were well protected in the package, so there were no scratches from the shipping of the boards.

Quality

The boards have a good quality for the chosen options and the price. The alignment of the layers is not perfect, but everything is in an acceptable range.

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The front side of the two boards. Continue reading Boards in Good Quality from SeeedStudio Fusion

Eurocircuits Delivered Astonishing Perfect Panels

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.

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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.

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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.

How to Design a Cheap Plant Watering Sensor (Part 5)

This is the fifth part of the meta-tutorial, where I talk about designing a cheap plant watering sensor. If you did not already read the firstsecondthird and fourth part, please do it now. These parts contain a lot information which lead to this point of the tutorial.

The fourth part ended with step 20, where I did usability tests and stability tests using the preliminary firmware. This article will focus on designing the final board for the project.

Step 21: Design the Final Board

Designing a good board is like one of these puzzles with quadratic tiles, where you try to lay down a 3✕3 set where all edges match. Often a small change result in many follow up changes, so you have to rip-up a lot of routes and design them in a new way.

My goals for the board were:

  • Everything, except the two LEDs, should go to the top side of the board.
  • Reduce the amount of vias to the absolute minimum.
  • Create a ground pour, especially around the oscillator part, to reduce noise.
  • Move the button as far as possible from the oscillator to minimise the influence if the user presses the button.
  • Make it as small as possible.

I worked with small iterations, checking the design after each iteration and checked the design against my goals. To keep track of the changes, I versioned each larger iteration. This way I could go back at a later stage for comparison or if a change did not turn out well.

The Tools

I worked with Autodesk Eagle to create the board. This tool is in the current state far from perfect, but it is cheap and has all required features for the task. For me personally, these are the features I need to design a board:

  • Smart routing editor which is linked to the schema.
  • Quick and easy way to create vias and see the required connections.
  • Good library support for symbols and packages.
  • Design rule checks.
  • Quick board preview to check label placement and design.

I described some issues of Eagle in this post:

12 Time Wasting Issues in Autodesk EAGLE

As you can see, these are not very advanced features and are supported by almost all good board editors. I never use the auto router, because I do not have time pressure or have to do repetitive tasks. Continue reading How to Design a Cheap Plant Watering Sensor (Part 5)

A Versatile ATtiny Programming Adapter

As mentioned in my article about designing a cheap plant watering sensor, I built a small adapter which can be used to pre-program the ATtiny13A. This is necessary, because once soldered on the board, I only have a debugWire interface, which has to be enabled first.

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The adapter has a small 50mil JTAG header, where the Atmel ICE can be connected with the board. There is also room for a USB mini jack, which is used to power the MCU while programming. A small on-off switch is used to power the MCU and a LED is placed as indicator to see if the MCU has power. The assembled board looks like this:

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One of the DIL/ZIF adapters is mounted on top of the female headers. Most of the adapters for SO-8, SO-14 and SO-16 will work with this board. Continue reading A Versatile ATtiny Programming Adapter

How to Design a Cheap Plant Watering Sensor (Part 2)

This is the second part of the meta-tutorial, where I talk about designing a cheap plant watering sensor. If you did not already read the first part, please do it now. It contains a lot information about constraints and decisions made which lead to this point.

The first part ended with step 11, building a working prototype with the selected key components. So let us start with the next steps in this journey.

Step 12: Analyse and Measure the Prototype

Never forget why you actually built a prototype. It is your tool to verify all assumptions you made in the design phase. To do this you need the right measuring instruments.

The Power Usage

I start measuring the current of the circuit. This will show if my assumptions about the battery life will be true. For this test I use a multimeter which has a good resolution measuring in the µA range. The multimeter I use is the Testo 760-3 which is not a very well known brand. Multimeters are usually really poor at measuring low currents on low voltages, so let us see if this will work.

I also use a Fluke 114, but this one has no current measurement. It is sometimes very handy to have two multimeters, one to measure the voltage and a second one to measure the current.

For the first test I program the MCU to do all the tests in a loop and connect the power directly to the second part of the circuit. Now the power is always on and I can measure the current used by the MCU while doing the measurement.

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Just running, doing the measurement of the oscillator, the second part of the circuit uses at maximum ~1.2mA. This measurement phase should be as short as possible. Later we will analyse the timing. Continue reading How to Design a Cheap Plant Watering Sensor (Part 2)

Outmoded Sequencer Finished!

Hurray! I just finished the final Outmoded Sequencer device. The tuning of all frequencies was way faster than I expected, because I used a new method. Have a look at the following photo gallery before I tell you some details.

You can see the device is build like a control desk, with the PCB a little bit at an angle. The left knob on the top controls the speed of the sequencer and the right one the volume.

A did a few tests already and the idea with the steel balls is working, but not great – just ok. So sometimes they do not connect and you have to move them a little bit until they make contact again. Most of the positions are working always without problems.

It is a great fun to play with the device, changing the pattern while the melody is playing. Now everything is finished, I also can move two steel balls at a time which can create interesting variations.

Next I will do a detailed video, where I demonstrate the final Outmoded Sequencer. It should give you a better impression of the device in action. I will also setup a complete filter chain, so you can experience how easy you can use the sound of the sequencer as input to do various interesting effects.

I will also add the second part of the project page, where I explain some of the details about the magnet matrix and how the whole thing is built.

There are seven absolutely perfect PCBs left, so I think about to give them away if someone is interested into building the project. But be aware, this is no kit, just the plain PCB. You also have to use the exact same components as I did – or at least ones which perfectly fit into the holes. All components should be available to buy at various stores, and I will provide the exact part numbers.

Video: Assembling Final Outmoded Sequencer PCB

Here a short update on the progress with the final Outmoded Sequencer project. I did the whole assembly of the final PCB and connected everything. You can see part of the soldering process in the following video:

I accidentally cut a route on the bottom of the PCB, so I had to fix this with a short wire. It is not visible on the final device. The magnet matrix mentioned in a previous post is already securely fastened to the bottom and holds the steel balls in place.

There are only the final adjustments of the frequencies left to do. I have to tune each tone and add the last four missing resistors.