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Experimenting with MAX6955

Posted on Thursday, September 15th, 2016 in LEDs by DP | No Comments

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Florin wrote an article about experimenting with MAX6955:

My experimenting actually started with MAX6954. After many failed tries due to SPI issues (Maxim uses a special interpretation of the protocol, I read), I switched to MAX6955.
MAX6955 is the I2C sibling of MAX6954 (which uses SPI). They both have identical LED driving abilities, only the microcontroller interface part of the chips differ. Once, both chips were available in DIP-40 package. Now, MAX6955 only comes in SSOP-36 (MAX6954 is still available in DIP-40). Luckily, the pin configurations for the two chips are compatible, which allows for easy swap. For this reason, I designed a breakout board (shared at oshpark), so I can use the same setup I built for MAX6954.

More details at Florin’s blog.

Adding ADC to Microcontrollers without ADC

Posted on Thursday, September 15th, 2016 in AVR by DP | No Comments

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Scott Harden writes:

I recently had the need to carefully measure a voltage with a microcontroller which lacks an analog-to-digital converter (ADC), and I hacked together a quick and dirty method to do just this using a comparator, two transistors, and a few passives. The purpose of this project is to make a crystal oven controller at absolute minimal cost with minimal complexity. Absolute voltage accuracy is not of high concern (i.e., holding temperature to 50.00 C) but precision is the primary goal (i.e., hold it within 0.01 C of an arbitrary target I set somewhere around 50 C).

More details at Scott Harden’s blog.

CO2, temperature and humidity monitor

Posted on Tuesday, September 13th, 2016 in PIC, sensors by DP | No Comments

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An open source CO2 monitoring project from Roving Dynamics:

The project described below uses a MH-Z16 or MH-Z19 CO2 sensor and a DHT-22 (or DHT-11 if less accuracy is required) to measure the Temperature and Humidity. It has a 4 line by 20 character LCD Display to show the current readings and status, a warning alarm and two relays which can be triggered on a low CO2 (Generally above 1000 ppm) normally to switch on an extractor fan and a high level (4000 ppm) which will trigger a warning device such as an external alarm. There are two models I used the 0 to 5000 ppm device here but the code will be the same for the 0 to 10000 ppm model.

Project info at rodyne.com.

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, September 13th, 2016 in Free PCBs by DP | No Comments

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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.

Ultrasonic Anemometer

Posted on Tuesday, September 13th, 2016 in DirtyPCBs.com by DP | No Comments

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Lukas Fassler has designed and built an Ultrasonic Anemometer project with Dirty Board PCBs.

Full details at Soldernerd homepage.

New ESP8266 board

Posted on Tuesday, September 13th, 2016 in wireless by DP | 2 Comments

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M0xpd writes:

You can well see it is an engineering sample, because I’m squeezing the wrong size packages into locations (quarter Watt resistors where eighth Watt components should be, etc) and using a mishmash of different component types, but you’ll forgive me, I’m sure.
The new design presents the Expressif ESP8266 device on an Arduino-sized board, supported by a full USB programming interface and power supply.
I should be careful to explain – this is not a “shield”. It does not sit on top of an Arduino. It REPLACES the Arduino. It IS the processor – and a whole bunch more…

Project info at M0xpd’s blog.

App note: Class D audio amplifier basics

Posted on Sunday, September 11th, 2016 in app notes by DP | No Comments

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Class D audio amplifier an efficient amplifier by Infineon Technologies, Link here

A Class D audio amplifier is basically a switching amplifier or PWM amplifier. There are a number of different classes of amplifiers. This application note takes a look at the definitions for the main classifications.

App note: How to pick a click-and-pop suppressor

Posted on Sunday, September 11th, 2016 in app notes by DP | No Comments

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Audio noises click-and-pop suppression method from Maxim. Link here (PDF)

This application note presents the MAX9890 and MAX9892 which use different approaches to remove audible click and pop from headphones. Each device is uniquely suited to different applications.

App note Quick-Start: Driving 14-segment displays with the MAX6954

Posted on Saturday, September 10th, 2016 in app notes by DP | No Comments

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Guidelines from Maxim on using the MAX6954 to drive 14-segment monocolor LEDs, app note here (PDF!):

This article is how-to guide, intended as a quick learning aid for engineers considering using the MAX6954 to drive 14-segment monocolor LEDs.

The MAX6954 is a versatile display driver, capable of controlling a mix of discrete, 7-segment, 14-segment, and 16-segment LED displays through a serial interface. This application note shows a typical application and configuration for driving eight mono-color, 14-segment LEDs.
See the MAX6954 data sheet for additional information about MAX6954 features.

An Arduino Terminal

Posted on Saturday, September 10th, 2016 in Arduino by DP | No Comments

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Peter Scargill writes, “As it happens I’m experimenting on a 1284 chip which while being Arduino-compatible kind of, it does have another serial port, so without disconnecting my FTDI – I hooked up the second serial port to the home control serial and fired the DEBUG command at the latter.
As you can see on the left, a perfectly usable terminal. At this point despite YEARS of VT-100 wilderness I’d mastered the colours and scrolling area controls – thanks to this handy VT-100-related link. Not all of the commands work and in order to make a character counter I had to do a custom colour save.”

More details at Scargill’s Tech blog.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, September 9th, 2016 in Free PCBs by DP | 3 Comments

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Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

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Teardown of a Static fieldmeter

Posted on Thursday, September 8th, 2016 in Teardowns by DP | No Comments

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teardown of a Static fieldmeter from Kerry Wong:

Static fieldmeters (or electrostatic fieldmeters) are typically used for non-contact measurements of the electrostatic field strength (usually in kV) of charged objects. These are highly specialized test instruments and most hobbyists probably seldomly have the opportunity of coming across one. So in this post and a companion video towards the end, we will take a look at how it works and what’s inside.
An electrostatic fieldmeter comes in handy when handling ESD sensitive electronics components, especially those with metal oxide layers (e.g. MOSFET, CMOS chips). These devices are sensitive to ESD and a typical damaging voltage level is only several hundred volts. Most datasheet lists human-body model (HBM) and charged-device model (CDM) voltage figures. Although these specified voltage may seem to be high (usually hundreds to several thousand volts), they can be exceeded in dry environments when electrical insulating materials are present.

More details at Kerry Wong’s blog.

Check out the video after the break. (more…)

PRU tips: Understanding the BeagleBone’s built-in microcontrollers

Posted on Wednesday, September 7th, 2016 in how-to by DP | Comments Off on PRU tips: Understanding the BeagleBone’s built-in microcontrollers

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Ken Shirriff writes, “The BeagleBone Black is an inexpensive, credit-card sized computer that has two built-in microcontrollers called PRUs. While the PRUs provide the real-time processing capability lacking in Linux, using these processors has a learning curve. In this article, I show how to run a simple program on the PRU, and then dive into the libraries and device drivers to show what is happening behind the scenes.”

More details at Ken Shirriff’s blog.

Teardown and analysis of an Agilent 86109B Optical/Electrical DCA-X oscilloscope module

Posted on Wednesday, September 7th, 2016 in Teardowns by DP | No Comments

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Teardown and analysis of an Agilent 86109B Optical/Electrical DCA-X oscilloscope module from The Signal Path:

In this episode Shahriar presents the inner workings of an Agilent 86109B optical/electrical DCA-X oscilloscope module. This particular model offers up to 50GHz of electrical bandwidth and an optical input capable of receiving up to 40Gb/s data rates. The differences between a real-time and sub-sampling oscilloscopes are presented with focus on ADC resolution, signal periodicity requirements and input bandwidth. The block diagram of the module as well as a sub-sampling oscilloscope is also presented.
The teardown of the module shows various components such as samplers, O/E conversion block, impulse generator as well as a step-recovery diode driver. I/O interfaces as well as various analog blocks are also shown. Several modules are further disassembled to observe the inner semiconductor designs under the microscope.

Check out the video after the break. (more…)

VHF Frequency Counter with PC Interface

Posted on Wednesday, September 7th, 2016 in RF by DP | No Comments

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Scott has published a new build:

This is the general idea behind how this frequency counter works. It’s so simple! It’s entirely digital, and needs very few passive components. sn74lv8154 is configured in 32-bit mode (by chaining together its two 16-bit counters, see the datasheet for details) and acts as the front-end directly taking in the measured frequency. This chip is “rare” in the sense I find very few internet projects using it, and they’re not available on ebay. However they’re cheap and plentiful on mouser, so I highly encourage others to look into using it! The datasheet isn’t very clear about its maximum frequency, but in my own tests I was able to measure in excess of 100 MHz from a breadboarded circuit! This utilized two cascaded ICS501 PLL frequency multiplier ICs to multiply a signal I had available (the 11.0592 MHz crystal the MCU was running from) by ten, yielding 110 MHz, which it was able to measure

Project info at SWHarden homepage.

App note: Using Cymbet™ EnerChip™ batteries instead of coin cells and super capacitors

Posted on Sunday, September 4th, 2016 in app notes by DP | 6 Comments

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High charge/discharge cycle and solid state reliability EnerChip from Cymbet make this a good replacement for super caps and coin cell backup batteries. Link here (PDF)

Primary and secondary (i.e., rechargeable) coin cell batteries, as well as super capacitors, have been in use for years as auxiliary power sources for applications including SRAM, real-time clocks, and microcontrollers. Now, a new type of rechargeable battery is available from Cymbet Corporation, the leader in thin film rechargeable micro-batteries.

Free PCB Sunday: Pick your PCB

Posted on Sunday, September 4th, 2016 in Free PCBs by DP | 33 Comments

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

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App note: Battery fuel gauge IC (LC709203F) for 1-Cell Lithium-ion (Li+)

Posted on Sunday, September 4th, 2016 in app notes by DP | No Comments

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Lithium-ion fuel gauge IC from ON Semiconductors. Link here (PDF)

The LC709203F is an IC that measures the remaining power level of 1-cell lithium-ion (Li+) batteries used for portable
equipment etc.
This product reduces fuel gauge errors with a unique correction technology during measurement of battery temperature and
voltage.
This technology has inherently high precision without the need for an external sense.

App note: Crystal oscillator basics and crystal selection for rfPICTM and PICmicro devices

Posted on Sunday, September 4th, 2016 in app notes by DP | No Comments

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The basics of crystals and crystal oscillators application note from Microchip, link here (PDF!)

This Application Note will not make you into an oscillator designer. It will only explain the operation of an oscillator in simplified terms in an effort to convey the concepts that make an oscillator work.
The goal of this Application Note is to assist the product design engineer in selecting the correct crystal and external capacitors required for the rfPICTM or PICmicro® device. In order to do this the designer needs a clear understanding of the interrelationship of the various circuits that make up an oscillator circuit. The product design engineer should also consult with the crystal manufacturer about the needs of their product design.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, September 2nd, 2016 in Free PCBs by DP | 3 Comments

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Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

(more…)

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