Topic: Electronics

Practical tips on electronic circuits, Raspberry Pi and Arduino

Pinecil V2

Disclaimer: the experiences described here are my personal opinion. I bought the product privately and paid for it myself.

So far I have used “traditional” soldering stations consisting of a base for power supply and temperature control and a handle with heating and replaceable soldering tips, like the Hakko FX-888D.

The crucial thing is the way the soldering tips are heated: the heating element is part of the handle and the soldering tips are only made of metal and are heated by the heating element. As a result, it takes a relatively long time for the soldering tip to reach the temperature of 350 °C required for lead-free solder after switching on. With the Hakko FX-888D this takes about 30-40 seconds. Since the temperature is also not measured directly in the soldering tip itself, the control can react to changes only with a delay.

Due to the long heating-up time, devices of this type also lack an automatic “sleep mode” to reduce heating power if the soldering iron is not used for a few minutes. This can lead to residues on the soldering tip oxidizing heavily and the soldering tip then having to be laboriously cleaned so that it accepts solder again.

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LED display HDSP-2000

The designation “HDSP-2000” refers to different variants of LED matrix displays that were developed by Hewlett Hackard and later also offered in a variant by Siemens. What they all have in common is that they display four characters with a matrix of 5×7 characters each with a height of 3.7 mm and use a DIL-12 housing. Multiple displays can also be placed side by side to form longer lines of text.

HDSP 2000, variants with ceramic carrier

The first displays with red LEDs were used in devices such as the HP 9825A in 1976. Later there were also other variants with yellow and green LEDs. A special feature is the elaborate construction with ceramic carrier and glass cover, which was colored in the red version to achieve a higher contrast.

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Hantek DSO2D15 digital storage oscilloscope

In the summer of 2021 I bought a digital storage oscilloscope (DSO) for my electronics workshop – a Hantek DSO2D15. This model is from the DSO2000 series and offers two channels with 150 MHz and an integrated signal generator with up to 25 MHz. There are also variants with 100 MHz (DSO2D10) and without a signal generator (DSO2C10 and DSO2C15). Now that I’ve been using it for over a year, it’s time for a review.

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IKEA Vindriktning with Tasmota and SCD30

I recently reported on my first experience with Home Assistant. The reason for this was that I wanted to collect the data from a suitably modified IKEA Vindriktning air quality sensor. The alternative firmware Tasmota, which can be used on ESP8266 or ESP32-based microcontrollers, serves as the basis for expanding the sensor. In addition, I now use the Sensirion SCD30 to measure the CO2 concentration in the room air, the relative humidity and the temperature.

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A whole range of devices is available under the name “M-Tester” which can automatically detect electronic components such as transistors, diodes, resistors, capacitors, etc. and test their properties. Hence the name: “M-Tester” is the abbreviation for “Multi-function Tester”.

All products of this type go back to the article “AVR Transistortester” at, which first described a transistor tester based on an ATmega8/168/328 and an LCD with 2×16 characters in 2012. The latest version of these devices, such as the “M-Tester T7” or “M-Tester TC1”, offers a color display with a graphic display of the components and an infrared sensor with which the function of remote controls can also be checked.

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Port expander MCP23017

If you want to control many I/O ports with a microcontroller you can use shift registers like the 74HC595. This solution is quite cheap but requires three lines to control and only works in one direction. If you also want to read in data you need another chip like the 74HC165 and additional lines if you want to have this parallel to the output.

A much more flexible solution is the port expander MCP23017. This chip will be controlled using I2C and provides 16 ports which can be configured individually as input or output.

There is also the variant MCP23008 with less ports and the variant MCP23S17 with SPI instead of I2C.

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AlphaClock – old meets new

AlphaClock is the sort form of “alphanumeric clock” as the displays used can also show text. The following video was done with the first version of the firmware.

A while ago I started to deal with the topic “micro controllers”. The first trials were with an Arduino micro which I also used to test old LED displays like the HDSP-2116 or DL-2416.

One advantage of the Arduino Micro ist that it can be plugged in directly to a breadboard and has a micro USB connector for data transfer and power supply. However from LCD2USB I also know the ATmega in a DIP package. For normal operation with external clock this controller only needs a crystal and two capacitors.

My idea was to combine an ATmega328P with two DL-2416 from 1987 and a DS3231 realtime clock module. The whole thing was also a project to learn to know the development environment as Visual Studio Code and PlatformIO as well as the way how the microcontroller works in terms of interrupt control and PWM.

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Arduino Uno Clone with WiFi

There are numerous replicas of the Arduino Uno, some with a different structure. What most replicas have in common is that they use a USB-TTL converter CH340 instead of their own controller for the USB connection. However, the connection to the Arduino IDE is made in the same way via a serial interface and the Arduino Uno bootloader required for this also works with these boards and is usually already available.

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Shift register 74HC595

If you work with microcontrollers like the ATmega328 (Arduino Uno) or ESP8266 (Wemos D1 mini) and want to control many lines at the same time, it can become a problem that there are not enough outputs are available.

For example: to control an HD44780-compatible LCD at least 6 lines are required if it is operated in 4-bit mode. However with a Wemos D1 mini there are only 11 outputs available or 9 if you want to use the serial data lines. If 6 lines are only used for the display, only 5 or 3 lines are available for other purposes. This can still be sufficient in some cases – but if you also want to connect sensors or buttons to control the unit, this may not be enough.

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