Therm RTD

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Matthew Reed writes:

Therm RTD is an addition to the Therm PID Controller family, with support for RTD temperature sensors. RTDs (or Resistance Temperature Detectors) use a coil of fine wire made from a material (usually platinum, copper or nickel) that has a very predictable temperature coefficient of resistance (or change in resistance as temperature changes). RTDs are generally more accurate and stable than thermocouples, and have a much greater range than thermistors – although they can tend to be more expensive than both.

More details at Protofusion.org.

Elektor 500ppm LCR meter case tips

LCR meter

NopHead wrote a blog post review of Elektor 500ppm LCR meter:

I recently bought a 500ppm LCR meter from Elektor because I didn’t have anything for measuring inductors or the ESR (equivalent series resistance) of capacitors, both of which are important for modern electronics, particularly switch mode regulators that have become ubiquitous.
It is also more accurate than any of my multimeters and has wider measurement ranges. For example it can measure resistance from 0.1mΩ to 1GΩ and capacitance between 0.1pF and 0.1F. This means I can now measure parasitics like contact resistance, stray capacitance and lead inductance. The principal reasons it can do this while my multimeters can’t is because it uses a four wire Kelvin connection to the device under test, and as well as measuring voltage and current, it also measures the phase between them.

More details at HydraRaptor blog.

#FreePCB via Twitter to 2 random RTs

BP-600x373 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.

1″ 100W hot-plate for SMT reflow

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kevinhub88 over at the Black Mesa Labs writes:

Black Mesa Labs has been using a $20 hot plate for a year now for soldering QFN ICs to PCBs. Only issue so far has been the size ( 10″x10″x3″ ) and thermal mass of the thing as it consumes precious microscope work area and unfortunately stays quite hot for 30+ minutes after a quick 4 minute reflow job. BML boards are mostly 1″x1″, so a 800W hot plate with a 6″ diameter heating surface is overkill for most jobs.
Wanting something much smaller for a typical BML PCB – stumbled across this 24V DC heating element on Amazon for only $14. It is rated for 24V at 5-7 ohms ( or 4.8Amps ). A surplus 19.5V DC 5A laptop power brick laying around BML seemed like a perfect match for this element. BML has safety rules avoiding designs above 48V – so the 100Watt 20V DC supply coupled with the 24V element seemed like a great way to make a lot of heat in a small surface area in a short amount of time.

Details at Black Mesa Labs project page.

Bus Pirate v3.8 free PCB build

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Hector built a free Bus Pirate v3.8 PCB.  The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

App note: WM9712 Jack plug auto-detection, hookswitch detection and microphone headset detection

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App note on Cirrus Logic’s WM9712 jack plug auto-detection by monitoring the connected headphone resistance. Link here (PDF)

This application note describes two operations associated with using headset. The first is the facility to automatically switch between a mono ear speaker and stereo headphones for use in a Smartphone, PDA etc. The second operation is a method which can be used to detect if stereo headphones have been attached or if a mono headset with microphone has been attached.

Free PCB Sunday: Pick your PCB

IRToy

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:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: An Introduction to MEMS Microphone Specifications

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An application note from Cirrus Logic on their MEMS microphones, which are small and perfect for wearables devices. Link here (PDF)

MEMS microphones are small form factor microphones, which translate acoustic sound pressure input into an electrical output response. They utilise the silicon wafer processes from the microelectronic industry to create high performance microphones of increasingly smaller geometries.

These processes give MEMS microphones a number of advantages over conventional electret condensing microphones (ECM), which has resulted in a general market transition to MEMS technologies for many of the latest consumer applications, including those requiring multi-microphone support or high quality capture.

The aim of this applications note is to enlighten readers with little or no experience of MEMS microphones to a point that they are confident in basic terminology and able to understand datasheet information to make product selections.

App note: Ultrasonic sensing basics for liquid level sensing, flow sensing, and fluid identification applications

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Here’s an app note from Texas Instruments: Ultrasonic sensing basics for liquid level sensing, flow sensing, and fluid identification applications (PDF!)

One of the most effective areas of sensor technology is ultrasonic, the science that measures the time interval between an ultrasonic signal that is sent and received, or what is commonly referred to as “timeof-flight” (TOF). TI is leveraging its ultrasonic expertise to deliver new signal conditioning solutions to fluid level sensing, fluid identification, flow metering, and distance sensing customers with its latest products (TDC1000 and TDC7200) based on time-to-digital converters (TDCs).
This application note provides an introduction to how Texas Instruments Ultrasonic Sensing solutions (TDC1000 and TDC7200) can be applied to popular applications such as liquid level sensing, flow sensing, and fluid identification.

Hacking DTM0660L based multimeters

I2CProg-600

Kerry Wong writes:

In my previous post, I did a review of the 6000 counts ennoLogic eM860T true RMS multimeter. This meter is based on a signal chip design using the versatile DTM0660L DMM chip. Besides the ennoLogic eM860T, several other multimeters such as UNI-T 139C, Velleman DV4100, Tekpower TP40 etc. are also based on the same chip.
One key feature of this chip is that most of the configurable parameters as well as the calibration data are all stored in an external EEPROM. This means that we could potentially change certain settings and enable certain settings (e.g. enabling UART communication, backlight duration, auto power off duration, etc.) by just changing values in the configuration EEPROM without having to do any hardware modifications. We will take a look at how to make these configuration changes in this post.

More info at Kerry Wong’s blog.

Free PCB coupon via Facebook to 2 random commenters

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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:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Modifying RAM SPD data

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Zak Kemble wrote a post on his blog showing how he modified the RAMs Serial Presence Detect (SPD) data:

Recently I brought some low-power Mini-ITX motherboards; a Gigabyte GA-N3050N-D3H and a Biostar N3050NH. These boards take SO-DIMM DDR3 RAM, the sort found in laptops. The boards are both pretty much the same, however the Gigabyte board lacks quite a few BIOS features and settings that the Biostar board has. One of those missing features was being able to set the RAM frequency. I wanted to run the RAM at its lowest frequency of 800MHz, but the Gigabyte board would run it at the its normal frequency of 1600MHz. Running at 800MHz reduced idle power consumption by about 0.12W on the Biostar board, a ~2% reduction… yeah ok, it’s a teeny tiny amount, but it was just a matter of flicking a switch.
To remedy this it looked like I was going to have to modify the RAMs Serial Presence Detect (SPD) data.

More details at Zak’s blog.

ChipStick – A small scale experimental Forth machine

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Ken Boak blogged about his ChipStick PCB build:

The ChipStick design has the following features:

  1. MSP430FR2433 with 15.5K FRAM and 4K SRAM
  2. External SRAM or FRAM device connected via SPI on USCI B0
  3. CH340G USB to serial converter IC on detachable section of board
  4. 3V3 voltage regulator
  5. Reset Switch and User LED
  6. 20 Pin DIL footprint to allow insertion into G2 Launchpad socket
  7. Programmable by SBW or BSL

Project info at Sustainable Suburbia blog.

Having cheap PCB’s made, part 2

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Batches of PCBs from Ivo of Knutsel.org:

The first batch was a new run of the LivingColors Arduino shield.
The second batch was a breakout board for the NiceRF SX1276 LoRa module. Here I experimented a little with contour routing.
The third batch was an adapter board to use no-name CC2500 modules in boards designed for the Quasar QFM-TRX1-24G. The boards are small (about 20 mm x 25 mm) and the minimal size for dirtypcbs PCB’s is 100 mm x 100 mm. Here I experimented with breakout panels, putting 4 PCB’s in one design.

More details at Ivo’s project page.

Mains 230VAC isolator

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Jaanus Kalde has built an isolator box:

Probing mains powered schematics is hard. Most oscilloscopes are earth referenced, so connecting ground probe to random spot of mains connected device will make a small explosion. Also there is the risk of electric shock by touching wrong part of the schematic while being in contact with something grounded like a desktop computer case
To combat these dangers I built an isolator box. I took an 1:1 transformer rated for 230 VAC 50 Hz mains voltage used in Europe. With 0.76 A current output capability it gives me ~170 W to play with. To make it even more useful I added a second output that goes through a diode bridge and has bunch of filter capacitors. This gives me rectified DC voltage to use, since most schematics rectify it anyway.

Project info at Jaanus’ blog.

Low voltage power supply unit

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Dilshan Jayakody writes:

In this post we introduce simple and flexible, regulated low voltage power supply unit. This power supply has provision for 4 outputs such as 1.5V, 1.8V, 2.5V and 3.3V. We mainly build this low voltage power supply unit to test (and power-up) low voltage MCUs, CPLDs and radio receivers. For this power supply we choose 1.8V, 2.5V and 3.3V to get it compatible with most of the LVTTL/LVCMOS devices. Other than that, we include 1.5V because there are several analog ICs are available for that voltage level.
This power supply unit is based on LM1117/AMS1117 voltage regulator series and for this design we use AMS1117-1.5, AMS111-1.8, AMS1117-2.5 and AMS1117-3.3 fixed voltage regulators. Except to above regulators this board can be use with AMS1117-2.85 and AMS1117-5.0 regulators.

Project info at Dilshan Jayakody’s blog.

Building a simple circuit probe

Probe 4

Vicente Jiménez has published a new build:

Sometimes you need to check one circuit and test some of its nodes. Usually a tester in voltage mode is a good solution, but it has a pair of problems. First, it measures about zero both when the node is driven at zero volts and when the node is floating (not driven at all). Second, it gives the information on the tester display, so you need to take the view from the circuit to the tester to check the voltage.
The proposed circuit somewhat qualifies as a logic probe. It should give no indication when the node is not being driven and it should give a different indication when the node is driven at high or a low voltage.
A lot of logic probes are not self powered. They rely on the circuit supply to operate. In my case I would like the probe to be usable also a as a continuity tester. If we set ground in one point of the circuit and we probe another point, the continuity can be detected between both points because a low level will be driven even if the circuit is not powered at all.

More details at r6500 blog.

An almost-GHz active differential oscilloscope probe (Part 3)

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Christer Weinigel wrote a series of three posts about how he built a active differential scope probe which is usable up to about a GHz:

This is part three of a series about building a active differential oscilloscope probe. Part 1 covered why I wanted a differential probe and the design of it. Part 2 covered actually building the the probe. The probe had much lower bandwidth than I had hoped for but it was still useful.

Project info at Christer’s blog.

#FreePCB via Twitter to 2 random RTs

BP-600x373

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.

Building a better RTL-SDR TCXO

Craig posted an article describing how he built a 28.8MHz RTL-SDR TCXO, that is available on github:

Here’s a scratch-built 28.8MHz TCXO capable of +-1ppm stability from 0C-55C; best of all, it’s not only easy to build, but is designed entirely from readily available and inexpensive components. For improved temperature stability, the main oscillator can even be replaced with one of many commercially available TCXOs!

More details at Analog Zoo project page.