One-Wire RS-232 Half Duplex (EE Tip #135)

Grun2-HalfDup

Traditional RS-232 communication needs one transmit line (TXD or TX), one receive line (RXD or RX), and a Ground return line. The setup allows a full-duplex communication. However, many applications use only half-duplex transmissions, as protocols often rely on a … Continue reading

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Low-Drop Series Regulator Using a TL431 (EE Tip #134)

EL2009-Kruger-SeriesReg

You likely have a stash of 12-V lead acid batteries (such as the sealed gel cell type) in your lab or circuit cellar. Below is a handy tip from Germany-based Lars Krüger for a simple way to charge them. A … Continue reading

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What Is Emissivity? (EE Tip #133)

Fig1-IR-Rad-Elektor

All objects radiate infrared energy. The warmer an object is, the faster the molecules in the object move about, and as a result the more infrared energy it radiates. The wavelength of this radiation lies roughly between 0.5 and 100 … Continue reading

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Measuring Jitter (EE Tip #132)

Figure 4—Time interval error (TIE) is another way to measure jitter. Here, the actual transitions are compared to a reference clock, which is supposed to be “perfect,” providing the TIE. This reference can be either another physical signal or it can be generated using a PLL. The measured signal’s accumulated plot, triggered by the reference clock, also provides the so-called eye diagram.

Jitter is one of the parameters you should consider when designing a project, especially when it involves planning a high-speed digital system. Moreover, jitter investigation—performed either manually or with the help of proper measurement tools—can provide you with a thorough … Continue reading

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DIY Single-Board Computer (EE Tip #131)

Photo 2—This is the N8VEM in its $20 stand-alone incarnation. Even without any other boards, this SBC provides sufficient I/O and storage options to be a full-fledged CP/M computer.

In the early 1990s, nostalgic users wrote software emulators to relive the “vintage” experience of their old Commodore 64 or Apple II. Others preferred the actual hardware and began collecting classic computers. As their old machines occasionally broke down, people … Continue reading

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