Probe a Circuit with the Power Off (EE Tip #14)

ComponentsDesk-iStock_000036102494Large

Imagine something is not working on your surface-mounted board, so you decide use your new oscilloscope. You take the probe scope in your right hand and put it on the microcontroller’s pin 23. Then, as you look at the scope’s … Continue reading

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Read Your Technical Documentation (EE Tip #145)

MCU

Last year we had a problem that showed up only after we started making the product in 1,000-piece runs. The problem was that some builds of the system took a very long time to power up. We had built about 10 prototypes, tested the design … Continue reading

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Impedance Matching Matters (EE Tip #145)

Figure 1: Impedance matching requirements must be anticipated. In particular, any embedded antenna will surely need manual matching for optimal performance. If you forget to include some area for a matching network like this one on your PCB, you won’t achieve the best performance.

RF designers, as well as more and more digital-oriented designers, are used to thinking about impedance matching. But it is very easy to forget it when you are designing a non-RF project. A non-matched circuit will generate power losses as well as nasty … Continue reading

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Liberally Apply Test Points (EE Tip #144)

MCU

When I first started designing, I did not understand the need for the scope posts for hardware test points. I could always tack on a wire or, with many through-hole parts, connect my scope right to the chip. But now test points are essential. … Continue reading

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Use Watchdog Timers (EE Tip #143)

ComponentsDesk-iStock_000036102494Large

Watchdog timers are essential to many complete electronic system designs.  As Bob Japenga explains, following a few guidelines will help make your designs more effective. No longer used in just the realm of fault-tolerant systems, independent watchdog timers are put on systems … Continue reading

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Got Problematic Little Bits? (EE Tip #142)

Source: Raymond Vermeulen (Elektor, October 2011)

While testing a project, something strange happened (see the nearby image). The terminal showed nonsense, but the logic analyzer properly displayed “Elektor” in ASCII. The latter also indicated that the UART was operating at 4800 baud instead of the 19200 … Continue reading

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Troubleshoot Electronics Problems with Logging (EE Tip #141)

datalog

Electrical engineers often develop “headless” electronic systems—that is, systems without user interfaces. And many of those systems are embedded within product and are generally out of reach when problems occur. Bob Japenga is an engineer with some advice about logging … Continue reading

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Diode Bridge Solution (EE Tip #140)

Diode

Once I connected a battery up to a DSP in the wrong “direction,” thereby destroying the DSP. That incident drove home the necessity of “suspenders and belt” design. After the accident, my colleague and I added a diode to the … Continue reading

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Embedded Security (EE Tip #139)

EmbeddSecurity

Embedded security is one of the most important topics in our industry. You could build an amazing microcontroller-based design, but if it is vulnerable to attack, it could become useless or even a liability.   Virginia Tech professor Patrick Schaumont … Continue reading

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Don’t Trust Connectors, Solder, or Wires (EE Tip #138)

Using the wrong pinout for a connector is a common error, especially on RS-232 ports where it’s approximately 50% probable that you’ll have the wrong RX/TX mapping. Swapping the rows of a connector (as you see here) is also quite common.

Engineer Robert Lacoste is one of our go-to resources for engineering tips and tricks. When we asked him for a few bits of general engineering advice, he responded with a list of more than 20 invaluable electrical engineering-related insights. One … Continue reading

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Test Under Real Conditions (EE Tip #137)

Mark Csele's complete portable accelerometer design, which he presented in Circuit Cellar 266.  with the serial download adapter. The adapter is installed only when downloading data to a PC and mates with an eight pin connector on the PCB. The rear of the unit features three powerful
rare-earth magnets that enable it to be attached to a vehicle.

The world’s best engineers have one thing in common: they’re always learning from their mistakes. We asked Niagara College professor and long-time contributor Mark Csele about his biggest engineering-related mistake. He responded with the following interesting insight about testing under real conditions. … Continue reading

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Specs & Code Matter (EE Tip #136)

MCU

No matter how many engineering hours you’ve logged over the years, it’s always a good idea to keep in mind that properly focusing on specs and code can make or break a project. In 2013, Aubrey Kagan—an experienced engineer and … Continue reading

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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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