Using the ADS1115 in continuous mode for burst sampling

Edward Mallon writes, “The 16-bit ADS1115 has a programmable amplifier at the front end, where the highest gain setting providing a range of +/- 0.256 v and a resolution of about 8 micro volts. But readers of this blog know you can already approach 14-16 bit sensitivity levels with Arduino’s ADC by oversampling with lower Arefs & scaled ranges. PA1EJO demonstrated a ADS1115 / thermistor combination which resolved 5 milli Kelvin, but we reach that resolution on our NTC’s using the ICU peripheral with no ADC at all. The beauty of time-based methods is that they scale gracefully with sensors that change over a huge range of values. So why am I noodling around with this ADC module?”

See the full post at thecavepearlproject.org.

#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.

An ESP8266-based temperature, humidity and line voltage monitor

KA7OEI’s temperature/humidity/line voltage web
server/telemetering device
:

As anyone who reads this blog probably knows, I have a bit to do with the operation and maintenance of the Northern Utah WebSDR – a remote receiver system that allows anyone with Internet access and a web browser to listen to the LF, MF, HF and some of the VHF bands as heard from a rural site in Northern Utah. The equipment for this receiver system is located a small building in the middle of mosquito and deer-fly infested range land near brackish marshes – no-where that anyone in their right mind would like to be during most of the year. With the normal hot weather in the summer and many clear days, this building gets hot at times: It’s been observed to exceed 130F (55C) on the hottest days inside – a temperature that causes the fans on the computers scream!

App note: Oscillator design considerations

Interesting app note from Silicon Labs about oscillators used on their wireless SoC series 2 devices, oscillator basics included. Link here (PDF)

An oscillator is an electronic circuit which generates a repetitive, or periodic, time-varying signal. In the context of Wireless SoC Series 2 devices, this oscillator signal is used to clock execution of instructions and peripherals in the device. For radio communication the oscillator also provides an accurate and low noise frequency reference to the transciever. There are multiple ways of generating such a signal, each with different properties that influence project cost, board size, and stability of the clock signal.

App note: Safety considerations for Silicon Labs series capacitor isolators

Great in-depth about electronic isolators from Silicon Labs. Link here (PDF)

Isolators are widely used in automotive, telecom, industrial, and medical applications to provide protection for people and/or equipment from high voltage hazards. The robustness of the isolator’s insulation, or “isolation barrier”, over the operating life of the equipment is key to ensuring safety against electric shock in these applications.

Measure voltage and current with the Tiny V/A Meter

Here’s KarlTorp’s palm-sized Tiny V/A:

Tired of replugging your multimeter when you want to measure both voltage and current on a small project? Tiny V/A meter is the device you need!

Via Arduino Blog.

Check out the video after the break.

Continue reading “Measure voltage and current with the Tiny V/A Meter”

CyberDeck ZBS

Recycled cyberdeck made from old project Raspberry pi Zero Boot System @ Facelesstech:

So when I redesigned my ZBS (zero boot system) I decided to also make a thinner version of my portable raspberry pi setup. This worked out great and I used it to develop the raspberry pi add-ons and the software for the ZBS. With the current pandemic its a real pain to order anything or get PBC’s made because of the long postage times.

Check out the video after the break.

Continue reading “CyberDeck ZBS”

DIY ARC reactor CPU performance monitor, powered by an Arduino

Michael @ the-diy-life.com posted detailed instructions of how to build your own Arc reactor CPU performance monitor:

In this project, I’m going to be showing you how to turn one of these popular DIY arc reactor kits into a useful Arc Reactor CPU performance monitor for your computer. It plugs into one of your computers USB ports and displays your CPU performance on the OLED display and the arc reactor pulses according to your CPU usage, increasing the pulse frequency with an increased CPU load.

Project info at the-diy-life.com.

Check out the video after the break.

Continue reading “DIY ARC reactor CPU performance monitor, powered by an Arduino”

App note: Automobile harness protection

Polyswitch fuse use in automobile, app note from Littelfuse. Link here (PDF)

A vehicle’s ideal harness scheme has a hierarchal, tree-like structure with main power “trunks” dividing into smaller “branches,” with overcurrent protection at each node. This architecture allows the use of smaller, space-saving wires that can reduce weight and cost. It also optimizes system protection while providing fault isolation, which ultimately improves reliability.

Using resettable circuit protection devices that do not need to be driver accessible offers designers a number of solutions that may be used separately or in combination. A single junction box located in the instrument panel may still be employed. However, rather than being positioned close to the conventional fuses, resettable PolySwitch devices can be located inside the box or on another face, which can save frontal area. Moreover, placing them closer to the connectors allows the trace’s length to be reduced. As a result, the overall junction box can be downsized.

App note: Automatic AC line voltage selector

Implementation of automatic AC line voltage selector, App note from Littelfuse. Link here (PDF)

In some cases, appliances and equipment are able to operate when supplies by two different levels of AC line voltage to their main terminals (10V or 240V). This is why, it is very common that appliances and equipment have mechanical selectors or switches as an option for selecting the level of voltage needed. Nevertheless, it is also very common that these types of equipment can suffer extensive damage caused for not putting the selector in the right position. To prevent these kind of problems, thyristors can be used as a solution for making automatic voltage selectors in order to avoid possibilities of equipment damage due to over or low voltages AC line supplies to them.

Using modular synth to control Atem camera switching over WiFi using ESP8266

Sebastian writes:

I’ve been wanting to control my camera switching from my modular synth. So I made a setup where a low to high transition on a digital input on an ESP8266 module generates an OSC message on the WiFi network for the ATEM Mini Pro switcher to change cameras. Here, it’s triggered from the kick but it could be any clock, gate or trigger signal. Makes use of atemOSC.

More details on Little-Scale blog.

Check out the video after the break.

Continue reading “Using modular synth to control Atem camera switching over WiFi using ESP8266”

#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.

Experimental Zener diode tester

Dilshan has published a new build:

Automatic Zener diode tester is capable of identifying Zener diodes up to 27.5V. Apart from that, it can be used to recognize leads of the diodes/Zeners and detect damaged diodes. This tester is designed using well-known ICs such as MC34063 and PIC16F88.
This unit provides approximately 5% to 15% accurate readings. Based on our observations, the accuracy of this unit can increase by using resistors with 1% tolerance, stable booster circuit, accurate sampling method(s), and with a more optimized PCB layout.

More details on Dilshan Jayakody’s blog. Project files are available on GitHub.

App note: P-channel power MOSFETs and applications

Another app note from IXYS on P-Channel power MOSFET application. Link here (PDF)

IXYS P-Channel Power MOSFETs retain all the features of comparable N-Channel Power MOSFETs such as very fast switching, voltage control, ease of paralleling and excellent temperature stability. These are designed for applications that require the convenience of reverse polarity operation. They have an n-type body region that provides lower resistivity in the body region and good avalanche characteristics because parasitic PNP transistor is less prone to turn-on. In comparison with Nchannel Power MOSFETs with similar design features, P-channel Power MOSFETs have better FBSOA (Forward Bias Safe Operating Area) and practically immune to Single Event Burnout phenomena. Main advantage of P-channel Power MOSFETs is the simplified gate driving technique in high-side (HS) switch position.

App note: Parallel operation of IGBT discrete devices

Guidelines for parallel operation of IGBT devices discuss in this app note from IXYS. Link here (PDF)

As applications for IGBT components have continued to expand rapidly, semiconductor manufacturers have responded by providing IGBTs in both discrete and modular packages to meet the needs of their customers. Discrete IGBTs span the voltage range of 250V to 1400V and are available up to 75A (DC), which is the maximum current limit for both the TO-247 and TO-264 terminals. IGBT modules cover the same voltage range but, due to their construction, can control currents up to 1000A today. However, on an Ampere per dollar basis, the IGBT module is more expensive so that for cost-sensitive applications, e.g. welding, low voltage motor control, small UPS, etc., designs engineers would like to parallel discrete IGBT devices.

cVert, a truly random MIDI controller

cVert, a truly random MIDI controller @ danny.makesthings.work

cVert is the result of an idea I’ve been kicking around for years, and took a few months of work to bring to fruition. The idea was to use a Geiger counter as a true random number generator to give a non-deterministic input for computer art or music. The result is a MIDI controller with a large amount of control removed – it plays a random musical note every time a radioactive decay is detected.

All files are available on GitHub.

Check out the video after the break.

Continue reading “cVert, a truly random MIDI controller”

DIY home made portable oscilloscope

An ATmega328 based portable home made oscilloscope with ADC from Creative Engineering:

It is basically a small scaled digital oscilloscope. It is capable of displaying all type of waveform like sine, triangular, square, etc. It’s bandwidth is above 1 MHz and input impedance is about 600K. The device is mainly using the ATmega328 micro-controller as the heart and is assisted by a high performance ADC (TLC5510) which is capable of taking up-to 20 mega samples per second and thus increasing the span of bandwidth which can be analyzed by our device. In addition to that, in-order to make the device portable Li-ion battery is used , which will be suitable to be fitted into a confined space.

See project details on Creative Engineering blog.

Check out the video after the break:

Continue reading “DIY home made portable oscilloscope”

Repairing an HP 3438A digital multimeter

Jeff (aka K6JCA) did a repair of an HP 3438A digital multimeter and documented the whole process on his blog:

This blog post is a record of my notes made while repairing an HP 3438A Digital Multimeter I had picked up last year at a local electronics swap meet. The 3438A is a 3.5 digit HP-IB controllable multimeter. It has five selectable functions: DC Volts, AC Volts, DC Amps, AC Amps, and Ohms. Of these five functions, three can be auto-ranged: DC Volts, AC Volts, and Ohms.

Extracting ROM constants from the 8087 math coprocessor’s die

Ken posted an article taking a closer look at Intel 8087 chip:

Intel introduced the 8087 chip in 1980 to improve floating-point performance on the 8086 and 8088 processors, and it was used with the original IBM PC. Since early microprocessors operated only on integers, arithmetic with floating-point numbers was slow and transcendental operations such as arctangent or logarithms were even worse. Adding the 8087 co-processor chip to a system made floating-point operations up to 100 times faster.
I opened up an 8087 chip and took photos with a microscope. The photo below shows the chip’s tiny silicon die. Around the edges of the chip, tiny bond wires connect the chip to the 40 external pins.

More details on Ken Shirriff’s blog.