DDS Basics (EE Tip #122)

Figure 1: The most basic digital signal generator is built with a simple binary counter. Its output sequentially
addresses the rows of a memory, which holds the successive points of the output signal. It is then converted to an
analog signal and filtered.

The simplest form of a digital waveform synthesizer is a table look-up generator (see Figure 1). Just program a period of the desired waveform in a digital memory (Why not an EPROM for old timers?), connect a binary counter to … Continue reading


Using Arduino for Prototypes (EE Tip #121)


Arduino is an open-source development kit with a cult following. Open source means the software and hardware design files are available for free download. This begs the question of how the Arduino team can turn a profit, and the answer … Continue reading


Basic Goertzel (EE Tip #120)

Figure 1: 
Figure 1—The signal flow of the basic Goertzel transform produces an output (y0) for each sample processed. The output is a combination of the current ADC sample added to the product of the previous output (y1) multiplied by a constant minus the previous output (y2). After a block of samples has been processed, the sum of the squares of y1 and y2 are computed to determine the relative amplitude of a particular frequency.

The basic Goertzel transform, which has been around since 1958, was derived from the discrete Fourier transform (DFT). It’s an extremely efficient method of detecting a single frequency component in a block of input data. Figure 1 depicts the signal … Continue reading


IR Remote Control Testing (EE Tip #119)

IR remote tester

On the Internet you can find them in all shapes and sizes: circuits to test remote controls. Here I describe a simple and cheap method that is not that well-known. This method is based on the principle that an LED … Continue reading


Desoldering Components (EE Tip #118)

Desoldering components from a printed circuit board.

Every engineer and technician sooner or later faces the challenge of having to desolder a component. Sometimes the component can be a large transformer with 10 pins or a power chip with many connections, and desoldering tools are typically around … Continue reading