App note: Paralleling linear regulators made easy

Various configuration of linear regulator for parallel operation discussed in this technical article from Analog Devices. Link here

Linear regulators provide a simple, low noise solution for dc-dc regulation. However, at higher VIN-VOUT differentials the low efficiency and high power dissipation of linear regulators limits the amount of output current that can realistically be delivered. Connecting multiple linear regulators in parallel spreads the load (and the heat) over several ICs, increasing the useful range of output currents a solution can deliver. However, connecting linear regulators in parallel is not always straightforward.

App Note: Optimizing CAN node bit timing to accommodate digital isolator propagation delays

Adding robustness by digital isolation and compensating for propagation delays to CAN network presented in this technical article from Analog Devices. Link here (PDF)

Controller area network (CAN), standardized under ISO 11898, is widely used in industrial and automotive applications. CAN protocols such as DeviceNet or CANOpen rely on the built-in error checking and differential signaling. Galvanic isolation can further enhance robustness, offering immunity to high voltage transients at a cost of added propagation delay. The optimal configuration of CAN nodes can allow the maximum data rate and distance even when isolation is present.

App note: Impedance characteristics of bypass capacitor

App note from ROHM Semiconductors about different type of bypass capacitors impedance and some tip when replacing them. Link here (PDF)

There are various types of capacitors. If you select parts only based on their capacitance values, the requirements for bypass capacitors may not be satisfied, leading to malfunction of devices or nonconformity to standards. This application note focuses on the impedance characteristics of capacitors, and explains cautions for selecting bypass capacitors.

App note: BA1117 dropout voltage

App note from ROHM Semiconductors about linear regulator dropout voltage. Link here (PDF)

The dropout voltage is the difference between the input and output voltages that is necessary for the stabilizing operation of a linear regulator. When the input voltage approaches the output voltage, stabilizing operation cannot be maintained and the output starts dropping in proportion to the input. The voltage at which this situation starts, i.e., the difference between the input and output voltages that is necessary for the stabilizing operation, is referred to as the dropout voltage.

Supercapacitor uninterruptable power supply (UPS) for Raspberry Pi

smbakeryt built a couple supercapacitor uninterruptible power supply (UPS) prototypes for his raspberry pi projects:

For my Convergent restoration, I decided to build an RASCSI to replace some failing SCSI hard drives. The RASCSI is a SCSI emulator built using a raspberry pi. Problem with these types of emulators is that if you carelessly power off the host computer (which was a perfectly acceptable thing to do back in the 80s), you end up also unsafely shutting down the pi — which can cause corruption of the SD-Card, loss of in-memory data, etc.
Back when I built David Gesswein’s MFM Emulator, he included a supercapacitor UPS that provided power just long enough to safely shut down a beaglebone. I figured the same thing would work for a raspberry pi.

Project info at smbaker.com.

Check out the video after a break.

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Reverse-engineering the first FPGA chip, the XC2064

Ken has written an article on reverse engineering the first FPGA chip, the XC2064:

The FPGA was invented by Ross Freeman1 who co-founded Xilinx2 in 1984 and introduced the first FPGA, the XC2064. 3 This FPGA is much simpler than modern FPGAs—it contains just 64 logic blocks, compared to thousands or millions in modern FPGAs—but it led to the current multi-billion-dollar FPGA industry. Because of its importance, the XC2064 is in the Chip Hall of Fame. I reverse-engineered Xilinx’s XC2064, and in this blog post I explain its internal circuitry (above) and how a “bitstream” programs it.

See the full post on Ken Shirriff’s blog.

App note: RS-485 communication link vs. the electric fence, A demonstration of RS-485 EMC robustness

Analog Devices’ RS-485 robustness demonstration by direct application of HV transient to the communication line. Link here

Industrial and instrumentation applications (I&I) require transmission of data between multiple systems, often over very long distances. The RS-485 bus standard is one of the most widely used physical layer bus designs in I&I applications. Applications for RS-485 include process control networks, industrial automation, remote terminals, and building automation such as heating, ventilation, air conditioning (HVAC), security systems, motor control, and motion control.

In these real systems, lightning strikes, power source fluctuations, inductive switching, and electrostatic discharge can cause damage to communications ports by generating large transient voltages. Designers must ensure that equipment does not just work in ideal conditions but also works in the ‘real world.’

App note: Using ESD diodes as voltage clamps

App note from Analog Devices on improving robustness of an amplifier by determining and mitigating internal ESD diode clamp electrical overestress. Link here

When external overvoltage conditions are applied to an amplifier, ESD diodes are the last line of defense between your amplifier and electrical over stress. With proper understanding of how an ESD cell is implemented in a device, a designer can greatly extend the survival range of an amplifier with the appropriate circuit design. This article aims to introduce readers to the various types of ESD implementations, discuss the characteristics of each implementation, and provide guidance on how to utilize these cells to improve the robustness of a design.

App note: Notes for temperature measurement using forward voltage of PN junction

App note from ROHM Semiconductors about the cautions when measuring temperature from PN Junctions. Link here (PDF)

The forward voltage of a pn junction can be measured to estimate the junction temperature of a semiconductor device. However, correct results may not be obtained if the measurement is performed incorrectly.

App note: What is a digital transistor?

See the simple composition of a digital transistor, app note from ROHM Semiconductors. Link here

A digital transistor is a bipolar transistor that integrates resistors. Bipolar operation tends to become unstable if the input (Base) is connected directly to the output terminal of an IC for voltage control. Inserting a resistor at the Base stabilizes operation.

A full-duplex tiny AVR software UART

Nerd Ralph writes:

I’ve written a few software UARTs for AVR MCUs. All of them have bit-banged the output, using cycle-counted assembler busy loops to time the output of each bit. The code requires interrupts to be disabled to ensure accurate timing between bits. This makes it impossible to receive data at the same time as it is being transmitted, and therefore the bit-banged implementations have been half-duplex. By using the waveform generator of the timer/counter in many AVR MCUs, I’ve found a way to implement a full-duplex UART, which can simultaneously send and receive at up to 115kbps when the MCU is clocked at 8Mhz.

See the full post on Nerd Ralph’s blog.

Back to basic – Mini CNC plotter

tuenhidiy shared detailed instructions of how to easily build your own low-cost Arduino mini CNC plotter from old DVD/CD player, project instructables here.

I have become too concerned with complicated details or new things, and now I should concentrate on basic, simple and important ideas. Getting back to basics, to start learning CNC, today I’d like to share how to easily build your own low-cost Arduino Mini CNC Plotter. With my version, I used the spring part of stapler as a main component for pen lift. During the process of doing this, I have referenced from many sources, studied & tried to clarify some point hard to grasp.

Check out the video after the break.

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Convert an ATX computer supply to a bench power supply

Using an old computer ATX power supply as a high-performance workbench power supply @ DroneBot Workshop:

A Bench Power Supply is an essential component for any serious electronics experimenter. But a good supply with multiple output voltages and a high current capability can set you back some serious cash. In this article we’ll look at an alternative – using an old computer ATX power supply as a high-performance workbench power supply. It’s a simple project that can give you a highly capable piece of equipment for next to nothing

Check out the video after the break.

Continue reading “Convert an ATX computer supply to a bench power supply”

App note: Advantages and limitations of the chopper-stabilized architecture of zero-drift precision op amps

App note from ON Semiconductors on the do’s and don’ts when using zero-drift precision op amps. Link here (PDF)

Zero−drift precision op amps are specialized op amps designed for applications that require high output accuracy due to small differential voltages. Not only do they feature low input offset voltage, but they also have high CMRR, high PSRR, high open loop gain, and low drift over temperature and time. These features make them ideal for applications such as low−side current sensing and sensor interface, particularly with very small differential signals.

Precision op amps are able to achieve “zero−drift” offset voltage, maintaining low input offset voltage over temperature variation and time, through a number of techniques. One of the ways that an amplifier can achieve this is by using a design technique that periodically measures the input offset voltage and corrects the offset at the output. This type of architecture is referred to as chopper−stabilized. Like all engineering solutions, zero−drift op amps also have their limitations. One of the less obvious is a result of the fact that the internal circuit of the chopper−stabilized amplifier contains a clocked system.

App note: A method of enabling more touch pads With 5-ch CapTouch module on LPC804 MCU

App note from NXP demonstrating capacitive pin channels expansion on LPC804 MCU with SWM (switch matrix) and scan sequences. Link here (PDF)

The CapTouch module on LPC804 supports only 5 channels by hardware. Normally, the device with up to 5 channels can fulfill some simple use cases. But if more channels are required by the original CapTouch module, the LPC804 might not support the usage. Even by the LPC845, the CapTouch module support up to 9 channels.
However, the SWM module on LPC804 can remap the CapTouch function to almost all the GPIO pins, while the CapTouch feature was the fixed function for pins on LPC845. With suitable software and the settings to CapTouch, the LPC804 use the different pins at different time slice, then it can support more channels than the hardware limited count by software. For example, 12 channels of normal dialing keyboard, or more.

App note: SPI flash programming algorithms for LP546xx

App note from NXP giving step by step guide on creating flash programming file for MDK and also using pre-compiled flash programming algorithm which can be used directly. Link here (PDF)

LPC546xx has external spi flash interface(SPIFI) which can R/W external flash with single/dual/quad mode. It also supports XIP mode which means code can be executed directly on spi flash. SPIFI greatly expands application’s code size, and makes it possible to store large data(image or even videos). However, downloading data into spi flash in development phase is always a troublesome problem, since different spi flash vendors have different command sets. Customers often meet the situation that original flash programming algorithm in MDK cannot fit their hardware, which causes downloading data incorrectly.

Yaesu FT-817 companion display

Andy (G7UHN) over at SWLing Post has written an article detailing the build of his genius companion control display for the Yaesu FT-817 transceiver:

Like so many I love getting out portable with my FT-817 but I do seem to spend so much of my operating time fiddling through the soft-keys because my most used functions (CW narrow filter, power and keyer settings to tune an ATU, A/B, A=B, etc.) are spread across different “pages” of the A,B,C assignments. Compared to the sublime experience of using my Elecraft K2 the FT-817 can be a little frustrating!
Last month, inspiration struck and I thought I could cobble together a small microcontroller and a little OLED display with some buttons to provide some extra soft-keys for the radio using the CAT serial port.

App note: Measurement, calibration and measurement uncertainty of OSRAM Opto Semiconductor LEDs

App note from OSRAM focuses on the measurement of LEDs and provides a fundamental understanding of optical measurement, calibration and measurement uncertainty. Link here (PDF)

With the recent rapid growth of the LED market and the development of its applications, LEDs have become more common. They can now be found in many new applications within the lighting community. These new applications have placed increasingly stringent demands on the measurement of LEDs. Hence, accuracy and precision are the keys in the optical measurement of LEDs. The radiometric, photometric and colorimetric quantities of the LEDs are typically derived from the optical measurement.

App note: Health monitoring

App note from OSRAM on design recommendation for LEDs and photodiodes intended for health monitoring. Link here (PDF)

Wearable applications enable the monitoring of vital signs for healthcare reasons and also for daily life activity tracking.
This application note provides basic information on health monitoring as well as an overview of the potential products and electrical and optical design recommendations.