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Vacuum tubes are awkward, need always 6.3V filament and high supply voltage? No, they can also work on 3.3V. I have built a vacuum tube pre-amplifier that runs entirely on 3.3V, inclusive the filament voltage. Apparently, the electron emission of the filament still works at 3.3V. Despite the very low supply voltage, the tube amplifier still works well.

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30x10mm ATtiny3217 Arduino breakout board in DIL24

The Dily3217 is an Arduino compatible development board of 30x10mm, easy to integrate since it has a breadboard-friendly narrow DIL24 package. It is powered by the new ATtiny3217 and it has 21 I/O lines. It can be programmed with an external USB FTDI adapter. It has more or less the same functionality as the Arduino Uno.

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My name is Albert van Dalen and I'm an inventor. I have 40 years of experience in electronics and software. During the development of the Maxun One solar bike, I constantly needed special equipment, parts and software, and so I rolled from one project to another. In September 2010, I started this website where I share my ideas and designs with the world. On my webshop, I sell products that I initially made for myself, but that were also interesting for others, such as a spot-welder controller and a solder-paste dispenser.

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DIY simple manual SMD solder paste micro-dot syringe dispenser

With this tool you can precisely dispense very small dots of solder paste. Although this solder paste dispenser is cheap and uncomplicated, it works better for small SMD parts than many automatic dispensers.

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This advanced controller is used by many people and has a unique reduced inrush current circuit that prevents main fuse blow up.

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I have developed the D.I.Y spot welder because I needed a special spot welder for the building of my Maxun One solar bike. It turned out that the spot welder is being built by many people worldwide, so I have published here the entire building project.

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This Arduino board can be used for any project where something needs to be controlled and that is menu-driven.

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The SAM 15x15 is a very small Arduino development board, with the same powerful controller as the Arduino Zero: the SAMD21G18.
All I/O pins are used: despite the small size, it has more I/O pins than the Arduino Zero or SAMD21 Mini/Dev Breakout: 34 instead of 21. Due to the very small dimensions it will fit easily into all embedded electronic projects, even in microdrones.

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Switches and push buttons need debouncing. It is straightforward to do this with software, using a library. The advantages of the Switch library are:

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For programming Arduino compatible microcontrollers, there are three different connectors in use: ICSP, FTDI or UPDI. Because these connectors are only used during programming and then remains unused, I have found a solution where no physic program connector is needed anymore.

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To be able to modify and repair the Chinese S-KU63 e-bike motor controller I have redesigned it. The S-KU63 may also give insight into other Chinese motor controllers. Note that the S-KU63 is the successor of the KU63.

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Bosch Active Line 3 printed circuit board explained

For my solar powered bicycle, the Maxun One, I designed a very powerful and lightweight mid-drive motor. I also wanted to investigate whether I could use a Bosch Active Line 3 motor. The Bosch motor weight is 2975g, this is relatively lightweight for a mid-drive motor, but it is still too heavy for my solar bike.

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Minimum values for trace width and via size

Here are some common minimum values which are used by PCB manufacturers:

Track width

6mil (Recommend >8mil)

Track/Vias space 

6mil (Recommend >8mil)

Pads space

8mil

Silkscreen text size

32mil

Drill hole

0.3mm

SMT Solder Mask Width

0.2mm

Solder Mask Clearance

0.2mm

Incidentally we may need a smaller trace width of 4mil, e.g. under ball grid chips.

PCB trace width and via drill used in smartphones, laptops etc.

  • Samsung GT-S5660 smartphone: Trace width 2mil, via diameter 12mil
  • Acer laptop 2008: Trace width 4mil
  • Sparkfun-samd21-mini-breakout: Trace width 10 and 6mil, via drill 10mil
  • Arduino-Zero-Pro-V3: Trace width 16 and 8mil, via drill 16mil

How to choose resistor and capacitor SMD size

Note that the assembly of the small 0201 size is more expensive.

  • 0805 Very large and is not used much anymore.
  • 0603 The most used, also in laptops, except in smartphones. The advantage is the low assembly costs. You can still solder this size manually.
  • 0402 The most used in smartphones because of miniaturization.
  • 0201 This size is sporadically used in smartphones.
  • 01005 I have never seen this used.

PCB checklist

  • Carry out the Design Rule Check.
  • Check unconnected pins. In Eagle file > export Pinlist.
  • No traces under crystals and TO220.
  • Large pads for components that may need to be replaced.
  • Check if the Gerber files contain all layers, don’t forget Tdocument, Bdocument in Eagle.

Silkscreen text checklist

  • All text is vector
  • Pin1 at ICs, connectors and jumpers
  • PCB name and company name
  • Date or version
  • TS and BS
  • Name test pins

Online Gerber Viewer

Here you can upload the entire set of Gerber files in one go and see how the PCB looks like:
https://gerber-viewer.easyeda.com/

Online Gerber viewer Easyeda

Adding breadboard pads

I always place extra pads on a PCB, that allow easy modifications afterwards. Use a dummy via: square 42mil, drill 20mil. Delete the via-solder mask, in Eagle you can do this by: Edit > change > Stop > set on and then select the via.

PCB with extra perfboard pads

Using the PCB as a drilling jig for switches

It is difficult to precisely drill holes for switches in a front plate. I came up with a handy solution for that. Add a center hole in the middle of the switch, the PCB can then be used as a drilling jig:

 Tactile switch Eagle package with center hole

Cheap PCB manufacturing in China

I’m an inventor and regularly make electronics prototypes, nowadays this can be done with low costs in China. But many people already know this.

For example, a double-sided PCB of 10 x 10cm costs less than $10, including shipping. You will get always five pieces, even though you only need one. The PCB is completed with a solder mask and a silkscreen on both sides.

Make the first prototype PCB sloppy

The first prototype PCB can be designed quickly and sloppily. It is not necessary to spend time on aesthetics, it often has to be completely redesigned when many things change. During the development process you always get new ideas and insights. Designing fast and sloppy is however quite difficult for a precision neurotic as me.

 

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I have developed a cheap multimeter calibration reference by which you can calibrate a digital multimeter yourself. Here we calibrate my favorite multimeter, the PeakTech 2010, it has a lot of features and it cost just €35.

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These are my inventions up to now, see also the inventions in the pipeline. If you are interested, please contact Business Partners.

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I have inventoried my on-going projects, because I honestly speaking lost the overview. I had started many projects but many of them are on-hold because they, on closer inspection, cost years to finish and in the meantime other things had become more important and I keep getting interesting new ideas.

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