Inside the digital clock from a Soyuz spacecraft

Ken Shirriff has written an article on reverse engineering a “Onboard space clock” from a Soyuz mission:

We recently obtained a clock that flew on a Soyuz space mission.1 The clock, manufactured in 1984, contains over 100 integrated circuits on ten circuit boards. Why is the clock so complicated? In this blog post, I examine the clock’s circuitry and explain why so many chips were needed. The clock also provides a glimpse into the little-known world of Soviet aerospace electronics and how it compares to American technology.

See the full post at

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App note: Failure signature of electrical overstress on power MOSFETs

Nexperia app note about MOSFET’s destruction investigative hints that can be used for design improvements. Link here (PDF)

When Power MOSFETs fail, there is often extensive damage. Examination of the size and location of the burn mark, the failure signature, provides information about the type of fault condition which caused the failure. This document provides a catalogue of failure signatures from common electrical overstress failure modes. The catalogue can be used in forensic investigation of the underlying root cause of failure to improve module design and reliability.

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App note: Designing in MOSFETs for safe and reliable gate-drive operation

This app note from Nexperia discuss’ gate drive designs for safe operation of MOSFET. link here (PDF)

The MOSFET gate-source threshold voltage (VGS-th) and maximum gate-source voltage (VGS-max) are key parameters that are critical to the reliable operation of MOSFETs. The threshold voltage represents the voltage at which the MOSFET starts to turn on, whilst the maximum gate-source voltage is the maximum gate-source voltage that the MOSFET can withstand safely. VGS-max ratings vary between suppliers and between MOSFETs, which can make it difficult to choose appropriate MOSFETs for the application.

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24-bit stereo audio DAC for Raspberry Pi

Dilshan Jayakody has published a new build:

This project is about 24-bit stereo DAC, which we build for Raspberry Pi boards. This R-2R ladder DAC is developing around Intel / Altera EPM240T100C5N CPLD.
We developed this module after review the PT8211 DAC, which we tested a few months ago. Compare with PT8211 DAC, this module is capable to provide high-quality audio output with Raspbian OS.

See project details on Jayakody’s blog. Project files are available on GitHub.

from Dangerous Prototypes

Simple VU-meter circuit

VU-meter circuit built on a breadboard using transistors, diodes, resistors, and LEDs @ Build Electronic Circuits:

It’s basically a simple display for showing a value. It’s originally for showing signal level in audio circuits, but there’s no reason you can’t use it to show temperature, rain intensity, light level, or whatever other value you are measuring.

Check out the video after the break.

from Dangerous Prototypes

App note: How to protect mobile devices from ‘USB Kill’ threats

Great read from Bourns about USB killer devices and port protection solutions. Link here (PDF)

Researchers have long warned about the security risks of inserting other users’ USB drives into your PC, even those from whom you trust. If the threat of malware infections isn’t cause enough for concern, there have been stories of malicious USB thumb drives that have “fried” laptops. Does this seem like a far-fetched occurrence? Hearing of the threats, PC World documented the work of an electronics engineer who set out to create a prototype that could actually kill a mobile device’s USB port.

from Dangerous Prototypes

App note: Protecting USB Type-C Cable connectors featuring higher power & tighter pin spacing

Bourns’ built-in thermal cut-off devices adds extra protection from faults directly on USB Type-C cables. Link here (PDF)

The now ubiquitous Universal Serial Bus (USB) standard was initially developed in 1994 with the intent of providing a communication standard to improve and simplify communication between the PC and peripheral devices. An updated version of the USB interface standard is the USB 3.1 Superspeed+, which doubles the data rate to 10 Gbps – a 2x improvement of the previous generation USB 3.0 Superspeed. USB 3.1 Superspeed+ is backwards compatible with USB 1.1, 2.0 and 3.0 with a power delivery projected at 100 W. This gives users enhanced data encoding for more efficient data transfer offering higher throughput and improved I/O power efficiency.

In addition to the increased power capability and bandwidth achieved in this updated USB standard, the connector has been changed. The original simple 4 pin D+/ D- Power and GND format has been upgraded and now combines multiple connector functions into one. The new USB Type-C connector features 24 pins in a smaller form factor.

A downside to this combination of increased power and the extremely tight pin spacing is heightened concern about potential safety and fire hazards due to the possibility of thermal runaway at the connector. To deal with these potential threats, it is recommended that electronic equipment manufacturers and connector and cable manufacturers integrate overcurrent and overtemperature protection into the Type-C connector.

from Dangerous Prototypes

FIREO – a low power SSB/CW tranceiver with its unique speech processing

Kang.K.P.S. writes:

“FIREO” (Pronounced FIRE-O), is basically a bit of non-conventional QRP (low power) SSB/CW transceiver design in which speech compression is implemented using FM limiter circuit. This unique approach of speech processing increases the effective average transmitted power and thus it improves on the signal strength reports at the receiving end. Consequently this technique also helps to cut through any man made or natural noise, very effectively.

See the full post on Small Wonder QRP blog.

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Compact Si5351 based SDR

Ray Ring has written an article detailing the build of his mini SDR radio using FV-1 Audio processor and Si5351:

This is a revised version of my FV-1 based SDR. I replaced the CS2100 clk generator with the Si5351 clk generator. The Si5351 has some advantages over the CS2100, namely you can generate quadrature clks directly. This simplifies the hardware design and improves the quadrature accuracy. The sideband rejection in LSB/USB modes is impressive..somewhere around 60 db as best I can measure.

More details at

Check the video after the break.

from Dangerous Prototypes

An ATmega brushless sensored motor driver v02

David Gironi writes, “Brushless electric motor (BLDC motors) are synchronous motors that are powered by a DC electric source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor. Hall sensored motors uses hall effect sensors or a rotary encoder to directly measure the rotor’s position.

See the full post on David’s blog.

Check out the video after the break.

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