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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Battery Charger Design (EE Tip #130)

Figure 1: This lead-acid battery charger uses Texas Instruments’s UC2906 IC.

It’s easy to design a good, inexpensive charger. There is no justification for selling cheap, inadequate contraptions. Many companies (e.g., Linear Technology, Maxim, Semtech, and Texas Instruments) supply inexpensive battery management ICs. With a few external parts, you can build … Continue reading

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Active ESD Protection for Microcontrollers (EE Tip #129)

Figure 2—Typical ESD protection circuit, as found in an Atmel microcontroller

Microcontrollers need to be protected from of electrostatic discharge (ESD). You can use the circuit described in this post when you have an application requires a greater degree of ESD protection than what you get from an IC on its … Continue reading

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Op-Amp Versus Comparator (EE Tip #128)

SPICE-Sim-Feat

Practically every lecture course or textbook on electronics describes how to use an operational amplifier as a comparator. Here we look at the possibility in more detail, and see how it can often be a very poor idea. The idea … Continue reading

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Build an Adequate Test Bench (EE Tip #127)

Test Board

It’s in our makeup as engineers that we want to test our newly received boards as soon as possible. We just can’t wait to connect them to a power supply and then use our test bench equipment (e.g., generators, oscilloscopes, … Continue reading

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