This article shows how to build a simple Triplexer (Diplexer plus integrated DC Bias-T) for use with commercial TV LNBs for QO-100 or X-band microwave experiments. Introduction When using modified, commercial LNBs for reception of the QO-100 amateur radio satellite or X-band microwave experiments, it is necessary to pass a clock-reference signal, a DC supply […]
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Electronics
Tremolo DSP Effect for Arduino
This article continues my newly acquired interest in implementing digital signal processing algorithms on the Arduino GIGA R1 by showing how to implement a tremolo effect algorithm in software. After showing how to implement an Audio Loopback Device and a DSP Diode Clipping Algorithm for Overdrive and Distortion Effects on the Arduino GIGA R1 WiFi, […]
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DSP Diode Clipping Algorithm for Overdrive and Distortion Effects
This article shows how to approximate the behaviour of a regular diode in a mathematical equation and how to subsequently implement the behaviour in software. The DSP algorithm can be modified to implement different topologies, such as single diode clipping, dual diode symmetrical soft clipping or asymmetrical clipping. The easiest way to implement distortion through […]
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Critical length of a PCB trace and when to treat it as a transmission line
Ideally, the impedance of PCB traces should be matched to the load and source impedances. This becomes especially important in high-frequency and high-speed digital PCB designs. Various rules of thumb are available to determine the critical length at which a PCB trace should be treated as a transmission line. Below this critical length, an impedance […]
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Etching PCBs using hydrochloric acid and hydrogen peroxide
Choosing the right etchant for home made PCBs could be a science on its own. Some people prefer ferric chloride, some advocate for sodium persulfate and I personally prefer hydrochloric acid and hydrogen peroxide. This article shows how to use a mixture of hydrochloric acid and hydrogen peroxide in a safe and controllable manner. UPDATE: […]
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Universal Clock Translator using Renesas VersaClock 6E Devices
Due to the popularity of the QO-100 geostationary amateur radio communication satellite, precision GPS reference frequency sources (GPSDO) are becoming more and more common in home labs. The desire to derive different, fixed frequency signals from a GPSDO has similarly been increasing as different devices requiere different reference clocks with different frequencies. Therefore, this article […]
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Arduino GIGA R1 WiFi | Audio Loopback Example
This article shows a basic sketch outline to use the Arduino GIGA R1 WiFi for audio DSP experiments. The sketch presented makes use of the Advanced Analog Library to implement a simple audio loopback device. UPDATE: There also is a German version of this article available on my German blog: Arduino GIGA R1 WiFi | […]
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LNB Modification for 10 GHz QO-100 Satellite Reception
This article shows how to modify an inexpensive LNB to accept an external LO-reference signal in order to be used as a K-band downconverter for QO-100 (Qatar Es’hail 2) amateur radio sattelite reception, radio astronomy or similar K-band experiments. This article is a shortened version of a scientific paper that I wrote as the lead […]
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Program uBlox GPS-module timepulse frequency (dynamically) with an Arduino
The uBlox GPS-modules are capable of providing various reference clock signals through the TIMEPULSE pin. By default, this pin outputs a 1 pulse-per-second (PPS) signal. For an upcoming project, a GPS disciplined oscillator (GPSDO), this output had to be adjusted to 100 kHz. Instead of using the manufactuer’s software, u-center, this task is supposed to […]
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JFET-based infinite impedance detector for AM-demodulation
The so-called “infinite impedance detector” is a circuit that was commonly used in the old days of vacuum tubes. Since vacuum tubes can be somewhat considered to be heated JFETs, it is evident that such a circuit can also be built using a more modern, silicon-based approach. This article covers my first experiments with a […]
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