Dual Mono AK4493 DAC (MK II)

An update on Dual Mono AK4490 DAC project we covered previously:

Since I was going to update the PCB design, I thought I might as well improve on as much as I could. So, the new board would:
*Include a new reclocking solution. I went for the best specc’ed chip out there, the famous Potato Semi PO74G374A. One chip would take care of the all of the I2S lines for both DAC chips.
*Add a couple of external 1.8V DVDD power supplies.
*Make some optimization of the LT3042 local regulators’ layout, in order to accommodate larger package capacitors (1206) where it would make most sense.
*Give access to the zero-detect lines of one of the dac chips. These pins could be used to easily implement auto muting of the output stage.
*Give access to the Enable pin of the Si570/Si544. The use of this Enable pin will be explained later.

See project details on Dimdim’s blog.

App note: 18pF crystals may not oscillate with energy saving MCUs

App note from Abracon about problems due on large crystal capacitive loading on smaller sized MCUs. Link here (PDF)

The 18pF plated Quartz Crystals may no longer be the ideal choice for a typical clocking circuit using an off-the- shelf MCU. As silicon geometries have shrunk over the last decade, the Pierce oscillator loop embedded in typical MCU’s has also evolved.

The latest 22nm, 14nm and now 10nm silicon geometries are bringing many benefits such as decrease in total IC size & reduction in power consumption – while incorporating feature rich capabilities. However, these advancements present challenges in the typical Pierce oscillator loop for system engineers.

In particular, these advancements in silicon geometry have decreased amplifier/inverter’s transconductance, gm , in the crystal oscillator loop. The results are power starved oscillation circuits that are marginally functional. These circuits run the risk of failing to startup due to total capacitive loading, changes in temperature & bias levels, etc.

App note: PCB trace vs. chip antenna design considerations

Abracon lists the requirement which antenna type best fit to your application. Link here (PDF)

The modern urban environment poses a challenge to high-speed designs involving Cellular, GNSS, WiFi/Bluetooth/BLE/ZigBee and LPWA protocols: the reflection, refraction, scattering, diffraction, polarization and absorption of signals necessitates highly efficient RF chains. Of all components in the chain, the antenna has the key role in establishing wireless connectivity.

A PCB trace antenna is given serious consideration when attempting to reduce the overall system cost; however, chip antennas offer better overall performance in terms of size selectivity and efficiency in most cases.

Repairing a vintage 40-kilovolt xenon lamp igniter

Ken Shirriff writes:

What do xenon lamps and the invention of radio have in common? The box below is a 1960s German high voltage unit that CuriousMarc obtained as part of an auction. After some research, we determined that it is an Osram1 igniter2, which generates a 40-kilovolt pulse3 to ignite a xenon arc lamp. The unit didn’t work, so I opened it up, figured out its circuitry, and fixed it, so we could generate some sparks. The circuit turned out to be very similar to a Tesla coil, although the sparks are much smaller.

See the full post on Ken’s blog.

Check out the video after the break.

Continue reading “Repairing a vintage 40-kilovolt xenon lamp igniter”

DIY voltage and current reference

Petteri Aimonen designed and built his own voltage and current reference:

When developing a data acquisition system, I ran into a need of having fairly accurate current reference to compare against, 0.1% accuracy or better. This is not a particularly high standard, but unable to find a suitable device in my price range, I chose to design my own.

Project info at essentialscrap.com.

#FreePCB via Twitter to 2 random RTs

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Tiny breathalyzer

Facelesstech posted a tiny breathalyzer project, that is available on GitHub:

A breathalyzer built around a ATtiny85 using a MQ-3 alcohol sensor displayed on a 4×7 segment display powered by a power bank. I 3d printed the body that slots over a power bank.

More details on Facelesstech blog.

Check out the video after the break.

Continue reading “Tiny breathalyzer”

App note: Cable compensation of a primary-side-regulation power supply

Another tech note from Richtek on power supply regulation with cable compensation. Link here

Cable compensation has been used to compensate the voltage drop due to cable impedance for providing a regulated charging voltage in battery charger applications. This application note uses a novel cable compensation method, which called cable minus compensation, as an example to describe the concept and design criteria for the cable compensation of a PSR flyback converter. The analytic results are also verified by the simulation results.

App note: Analysis of buck converter efficiency

Tech note from Richtek on buck converter profiling. Link here

The synchronous buck circuit is wildly used to provide non-isolated power for low voltage and high current supply to system chip. To realize the power loss of synchronous buck converter and to improve efficiency is important for power designer. The application note introduces the analysis of buck converter efficiency and realizes major power component loss in synchronous buck converter.

The ArduINA226 power monitor

ArduPicLab published the details on how to build a current, voltage and power datalogger with Arduino and the INA226 module:

In the past I have developed various projects of ammeters based on Hall effect current sensors such as the ACS712, or on High-Side Current-Sense Amplifiers such as the MAX4080SASA or made with operational amplifiers. All these systems have an analog output which must then be digitized. The INA226 sensor has a digital output and incorporates a 16-bit ADC for which a high accuracy and precision is obtained.

MCP4141 based digital potentiometer

Dilshan Jayakody has been working on an open-source hardware project MCP4141 based digital potentiometer, that is available on GitHub:

The main objective of this project is to create an experimental prototype of a digital potentiometer using Microchip’s MCP4141 IC. MCP4141 is available with end-to-end resistances of 5KΩ, 10KΩ, 50kΩ, and 100KΩ. This potentiometer-module can drive MCP4141 with any of the above mention resistances.

DIY motion simulator

Bogdan Berg has been working on a DIY motion simulator:

As you may have seen from some of my other posts on this blog, motorsports and cars in general are one of my passions. I try to attend at least couple track days in a season, and enjoy circuit racing greatly. However, costs can add up quickly, and living in Seattle leaves us with a lot of rainy days through fall/winter/spring, somewhat limiting the time window for optimal conditions on the track. Although racing in rain as an art in itself… 😉

See the full post at bogdanberg.com.

Check out the video after the break.

Continue reading “DIY motion simulator”

Inside a Titan missile guidance computer

Ken Shirriff has written an excellent in-depth look at a Titan missile guidance computer:

I’ve been studying the guidance computer from a Titan II nuclear missile. This compact computer was used in the 1970s to guide a Titan II nuclear missile towards its target or send a Titan IIIC rocket into the proper orbit. The computer worked in conjunction with an Inertial Measurement Unit (IMU), a system of gyroscopes and accelerometers that tracked the rocket’s position and velocity.

See the full post at righto.com.

DIY long lasting voltage regulator circuit for Raspberry Pi

Jithin @ rootsaid.com writes:

Raspberry Pi is simple, handy and cheap yet powerful single board computers of all time. It has USB ports to connect hardware such as pen drive, keyboard, mouse, HDMI port for display out, 3.5 mm port for audio and several GPIO pins to work with embedded projects, all of which can be powered using a mobile charger. You can even make it portable by simply connecting the mini USB port to a mobile phone power bank so that you can use your pi on the go. But if you connect more USB devices and use the GPIO pins, the power bank will drain off quickly. In this post, I will tell you how i made my own power supply unit using a Lithium Polymer battery and a voltage regulator.

Project info at rootsaid.com.

Building my own 50Ah LiFePO4 lithium battery pack

Kenneth Finnegan posted his DIY 50Ah LiFePO4 lithium battery pack build:

Several years ago, I had purchased a 20Ah 12V Lithium Iron battery pack from Bioenno for my various 12VDC projects. To help protect it, I ultimately built it up into a 50cal ammo can with a dual panel-mount PowerPole connector on the outside, which has proven really nice as far as battery boxes go:
*20Ah is a decent battery capacity for a small load
*The packaged Bioenno pack left some space inside the box to also store the charger it came with, some PowerPole accessories, etc
*The fact that you’re able to close up the box and use the power connectors on the outside once you’re using it is real nice

More details on The life of Kenneth blog.

Low cost open source ventilator

Johnny Chung Lee writes, “In the event that COVID-19 hospitalizations exhaust the availability of FDA approved ventilators. I started documenting a a process of converting a low-cost CPAP (Continuous Positive Airway Pressure) blower into a rudimentary Ventilator that could help with breathing during an acute respiratory attack. If interested, follow along the Github Project

More details on Procrastineering blog.

Looking inside a vintage Soviet TTL logic integrated circuit

Ken Shirriff examines a 1980s chip used in a Soyuz space clock:

The clock is built from TTL integrated circuits, a type of digital logic that was popular in the 1970s through the 1990s because it was reliable, inexpensive, and easy to use. (If you’ve done hobbyist digital electronics, you probably know the 7400-series of TTL chips.) A basic TTL chip contained just a few logic gates, such as 4 NAND gates or 6 inverters, while a more complex TTL chip implemented a functional unit such as a 4-bit counter. Eventually, TTL lost out to CMOS chips (the chips in modern computers), which use much less power and are much denser.

More details on Ken Shirriff’s blog.

App note: Nonideality of ground

Ground in PCB design, another app note about grounds from Renesas. Link here (PDF)

Ground is supposed to be ideal. It should be a black hole for stray currents where the voltage is always zero. Unfortunately, those stray currents travel through some non-superconducting material, so small voltages arise. You may not notice small changes in ground potential, you may, instead, notice surplus noise or instability or other unwanted attributes in your system. We are going to discuss ground. Every circuit is unique and grounding paths are different for every device on your board and in your system. Therefore, we are starting with an intuitive approach to try and give you a feel for the paths currents choose to travel and how that affects the ideal assumption of ground being zero volts.

App note: Grounding techniques

Renesas detailed app note about grounds. Link here (PDF)

Ground is taken for granted. We stand on it, we dig into it, we make mud pies out of it. The ground isn’t supposed to move. We don’t have to think about it; it just is. When it comes to grounding a circuit, we assume that our connections are as solid as the turf below our scuffed shoes. Many times, this is a reasonable assumption-but not always. How do we know when there is a problem with a circuit’s ground? What practices will ensure we construct a good ground?

No longer to be taken for granted, we define ground in ideal and real situations. Ground configurations and printed circuit board (PCB) examples will be presented.