Category Archives for Design

Marten Repeller inaudible 90 dB

Figure 1 shows the modest schematic of our ultrasonic sound generator. The heart of the circuit is formed by — and how could it be otherwise — a microcontroller, in this case a small one: the ATtiny25-20. But let’s start … Continue reading

19. February 2019 by sam
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RF Step Attenuator Circuit

There are two different but equivalent circuit configurations used to attenuate signals while maintaining impedance matching (in other words, the input and output impedances of the circuit are the same, but the signal level is not). These are called a … Continue reading

08. November 2018 by sam
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PCB Design Markings and component print

Try to provide designators for all component outlines and make sure they remain visible after the components are mounted. I like to orient designators the same way as the components, in rows and columns (see also Figure 3). Do indicate … Continue reading

08. November 2018 by sam
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PCB Design Use Design Rules

Use the design rules checks (DRCs) and electrical rules checks (ERC) to make sure all PCB elements respect them. Good design rules will help avoid traces from overlapping or coming too close to the board’s edge, help you find illegal … Continue reading

08. November 2018 by sam
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PCB Design Traces and planes

Keep traces as short as possible; you knew that, of course. This is especially true for high-frequency signals, but low-frequency and even DC signals benefit from short traces too. Not only are short traces good for signals, they also save … Continue reading

07. November 2018 by sam
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PCB Design Holes

Pads often have holes in them — vias have holes too. Mounting holes can be non-plated; holes in pads and vias are plated. You specify the plated-hole diameter for your vias and pads; it is the job of the PCB … Continue reading

07. November 2018 by sam
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PCB Design Pads

Component leads and terminals are soldered to pads on the PCB. For many parts the pads not only provide the electrical connection, they double as the mechanical mounting points for the part. It is therefore important that the pad is … Continue reading

07. November 2018 by sam
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PCB Design Automatic or manual routing?

CAD tool manufacturers and scientists spend and have spent many, many, many hours on developing and improving automatic routers and yet I have never been satisfied with the results of a single one of them. I also have never met … Continue reading

07. November 2018 by sam
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PCB Design Component Placement

Components should not be placed anywhere or anyway you like, not even when the circuit allows you this virtual luxury. For ease of installation, inspection and repair, components should be arranged in rows and columns, and oriented uniformly. Although for … Continue reading

07. November 2018 by sam
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A Small Glossary of PCB Design

Auto-router: Holy Grail of PCB design software developers Bottom: the lowest layer of the board stack, also still commonly known as solder side Class: resolution or density of a PCB; the higher the class, the smaller PCB elements and clearances … Continue reading

07. November 2018 by sam
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