App note: Current limits in electronic fuses using direct and Kelvin R limit connections

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App note from ON Semiconductor about eFuse or Electronic fuse. Link here (PDF)

The primary function of an Electronic Fuse, or eFuse, is to limit current, the same function provided by any fuse or positive temperature coefficient device (PTC). An eFuse, however, provides this function with much more versatility than either of these devices. An eFuse, unlike a standard fuse, need not be replaced after it functions and eFuses also respond more rapidly than a either a fuse or PTC. eFuses can also limit current in situations in which a traditional fuses and PTCs will not work. This is especially true when voltage is first provided to a circuit, such as during a hot plug operation, when inrush current can be extremely high. This application note will explain the basic operation of an eFuse’s current limit function and explain important eFuse concepts such as Overload and Short Circuit currents, and Kelvin versus Direct connection of the eFuse’s current sense resistor.

App note: The four benefits brought by using NCP12600

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App note discussing extended features of NCP12600, NCP12600 is a multi-mode controller for offline power supplies by ON Semiconductor. Link here (PDF)

Beside the novel multi−mode structure it embarks, the NCP12600 packs a lot of features such as an efficient short−circuit protection architecture, a start−up sequence with a slow switching frequency ramp−up, a fast reset when latched and an auto−recovery scheme when line cycle dropout occurs in latched versions. Let’s discover these novelties in the present application note.

Open source 22mm diameter PCB project

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An open source 22mm diameter PCB project from Concretedog, that is available on github:

So I posted a while back about how I had used these 22mm pcb’s I’d made in prototyping an ematch ignitor system for use in rocketry. Although I made these stackable boards so they would fit inside a popular size of Estes rocket body tube I’m aware that they are quite useful for lots of things. So i’ve open sourced them so anyone can get some made, or add improve or change them.
There are three boards,an Attiny85 board with some power LED and indicator LED, a SOT89 power supply board which could be built up with either a 3.3v or a 5v supply. Finally there is a “kludge” board which is useful for adding in some thru hole components into the system. Some quick pics here but in the files on Git each board is well documented in a pdf. All the dust components are 0805 so super accessible for hand SMD soldering. :)

See the full post at Concretedog blog.

Repairing the card reader for a 1960s mainframe: cams, relays and a clutch

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Ken Shirriff writes:

I recently helped repair the card reader for the Computer History Museum’s vintage IBM 1401 mainframe. In the process, I learned a lot about the archaic but interesting electromechanical systems used in the card reader. Most of the card reader is mechanical, with belts, gears, and clutches controlling the movement of cards through the mechanism. The reader has a small amount of logic, but instead of transistorized circuits, the logic is implemented with electromechanical relays.1 Timing signals are generated by spinning electromechanical cams that generate pulses at the proper rotation angles. This post explains how these different pieces work together, and how a subtle timing problem caused the card reader to fail.

See the full post on his blog.

Retropie plug in USB speaker

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A detailed instructions of how to make this DIY retropie plug in usb speaker from Facelesstech:

The 2 down sides to my ZeroBoy build I did recently were that it didn’t have a build in battery power and that it didn’t have sound. I seen that the MintyPi was using a USB sound card to give their handheld a speaker by soldering a speaker to the 3.5mm jack. So I thought I could do the same to add sound to my ZeroBoy.

Check out the video after the break.

App note: LEDs – The future of horticultural lighting

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LEDs used in a controlled environment greenhouse farms, an app note from Würth Elektronik. Link here (PDF)

Greenhouse farms may not be a new technology but with an every growing world population and the move towards sustainability, intensive yet highly efficient and standardized food production will increasingly become the norm in future years opening a potentially huge new agricultural sector that incorporates the latest technologies from the bioscience and engineering fields. But how can researchers and personnel from these separate fields understand the mutually dependent requirements of indoor greenhouses? Photosynthesis is the process that converts water and carbon dioxide into complex carbohydrates (i.e. sugars) and oxygen using energy from light. However, although the energy radiated by the sun that reaches the earth’s surface consists of the entire spectrum of visible light (and more), plants only utilize specific frequencies of light for photosynthesis. These frequencies are related to the absorption characteristics of different pigments that are present within organelles called chloroplasts that are responsible for different functions of photosynthesis.

Light emitting diodes are solid-state, light generating components that, have become and will continue to be one of the greatest drivers in the expansion of internal greenhouses due to their advantages over incandescent bulbs, fluorescent bulbs, high-pressure sodium lamps and mercury lamps. Their main advantage stems from their ability to generate specific wavelengths of light. To meet the requirements for Horticultural LED’s for Indoor-farming, Würth Elektronik offers the WL-SMDC SMD Mono-color Ceramic LED Waterclear series of LEDs. The WL-SMDC range has been expanded to include wavelengths of 450 nm (Deep Blue), 660 nm (Hyper Red) and 730 nm (Far Red), which have been selected to match the absorption spectra of photosynthetic pigments. In addition to the existing products in the range, a diverse range of combinations is possible that can be catered to the target cultivar.

App note: The behavior of electro-magnetic radiation of power inductors in power management

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Application note form Würth Elektronik about EM radiation radiated from inductors in DC-DC converters. Link here (PDF)

This Application Note focuses on the Electro-Magnetic (EM) radiation behavior of power inductor(s) in DC-DC converters, which is dependent on several parameters such as ripple current, switching frequency, rise & fall time of a switching device, the core material and its permeability and suggests several design tips to mitigate these EMI effects.