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ถูกปรับปรุง 13 hours 47 min ก่อน

1750Hz tone generator

อังคาร, 06/04/2019 - 19:13

Dilshan Jayakody published a new build:

The 1750Hz tone bursts are often used to trigger repeaters. There are several methods to build 1750Hz tone generators which including TC5082 divider, using MCUs, etc.
In this post, I present another 1750Hz tone generator which I built using 74HC4060 high-speed 14-stage binary ripple counter and 7.168MHz crystal. In this design, 74HC4060 is used to drive the crystal and divide its output by 4096. By using 7.168MHz crystal, this circuit produces 1750.0Hz square wave output with a 50% duty cycle.

See the full post on his blog.

App note: Magnetometer placement in mobile devices

จันทร์, 06/03/2019 - 00:00

App note from Kionix about magnetometer integration challenges from the mobile equipment point of view, and gives guidelines for the mounting position of the magnetic sensor. Link here (PDF)

Electronic devices contain many parts which can affect a magnetic sensor. When deciding the mounting position, it is necessary to consider the types of materials and the amount of current carried in proximity of the magnetic sensor. Accuracy of an electronic compass depends upon getting clean geomagnetic data from the magnetic sensor output without errors caused by other magnetic elements. These errors need to be canceled by calibration or correction.

App note: Using two tri-axis accelerometers for rotational measurements

อาทิตย์, 06/02/2019 - 20:00

App note from Kionix on utilizing 2 linear accelerometers to determine angular rotational rates. Link here (PDF)

In many applications, customers would like to measure rotational motions (angular velocity, angular acceleration) in addition to linear motions. Most often, gyroscopes are added to their end product to obtain the rotational information. In some instances, customers already have a system that contains two or more accelerometers. With some understanding of fundamental physics, they can extract more than just linear acceleration data from their system.

Decap a Chinese chip at home: Clone or not?

เสาร์, 06/01/2019 - 06:41

Sjaak writes, “It has been a while before I posted something useful. On my search for obscure chips, I came around another interesting Chinese chip (which I don’t reveal yet). The chip was advertised as a cheap drop-in replacement for a American IC so I suspected it would be a clone. I wanted to look inside the chip to check if that is true.”

More details at smdprutser.nl

Teardown of a Marconi 2305 modulation meter

พฤ, 05/30/2019 - 06:55

Kerry Wong did a teardown of a Marconi 2305 modulation meter:

I picked up a Marconi 2305 modulation meter off eBay the other day. As the name indicated, a modulation meter is used to measure the modulation characteristics of a source signal. The Marconi 2305 is capable of measuring amplitude/frequency and phase modulated signals from a few hundred kHz all the way up to 2 GHz.
The Marconi 2305 was built sometime between the late 70’s and 80’s. It is a pity that the iconic British Marconi Instruments went under in 1998 and had since changed hands a couple of times.

See the full post on his blog.

Check out the video after the break.

#FreePCB via Twitter to 2 random RTs

พุธ, 05/29/2019 - 06:53

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.

DIY inline refractometer

พุธ, 05/29/2019 - 06:49

DIY inline refractometer project from Anfractuosity:

The idea of this project is to image the refractometer output, then convert the position of the blue line, to a digital reading, using image processing. The idea is to measure the brix of wort during mash and sparging, so that sparging can be stopped around 1.010 SG, to avoid tannins.

More details on Anfractuosity blog.

Check out the video after the break.

Ham Radio HT turns CW (Morse) transceiver

อังคาร, 05/28/2019 - 06:55

Ham radio HT CW transceiver project from WhiskeyTangoHotel.com:

Really not much explanation needed; just connect as shown above.  This project uses an electronic keyer, but a simple straight key/oscillator combo could also be used.  Oh… and you will also need to know Morse Code.

App note: Light quality – White light parameters

จันทร์, 05/27/2019 - 00:00

App note from OSRAM on consistency of colors specifically white lights. Link here (PDF)

White light is not the same as white light. When different light sources are used, color differences may become visible. To understand why this can happen, it is necessary to understand how people perceive color and light. Nevertheless, it is possible to reduce the color shifts by choosing suitable white LEDs combined with an appropriate system setup. This application note provides basic information on optical quantities, color spaces and CIE chromaticity diagrams. Furthermore, it describes how color consistency for white light applications can be achieved.

App note: Ambient lighting design utilizing RGB LEDs

อาทิตย์, 05/26/2019 - 20:55

App note from OSRAM on using RGB LEDs or their MULTILED® for automotive interior lighting. Link here (PDF)

This application note describes the advantages and challenges of utilizing RGB LEDs for ambient lighting control. Besides pointing out practical challenges, preferred solutions for RGB LEDs are outlined and discussed to assist customers with engineering design solutions.

Free PCB coupon via Facebook to 2 random commenters

เสาร์, 05/25/2019 - 06:58

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:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook 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.

Edge-lit seven segment display

เสาร์, 05/25/2019 - 06:56

Debra over at Geek Mom Projects posted detailed instructions of how to build this edge-lit seven segment clocks:

This build combines small dozens of small laser-cut acrylic pieces which fit together with very tight tolerances. It uses skinny (4mm wide) LED strips which must be soldered, bent, and then slotted in between those acrylic pieces. When assembling the parts you must be willing to force pieces into place, even though it feels like you are stressing the brittle acrylic. You must also be willing to remove and re-seat said pieces and LED strips when it turns out they *can’t* actually be forced into place. At some point during the assembly there is a strong likelihood that you will have to remove everything and re-solder your LED strip when you realize that forcing everything into place broke one of the wires away from your LED strip or created a short circuit.

See the full post on Geek Mom Projects blog.

Check out the video after the break.

PocketPi MK2

อังคาร, 05/21/2019 - 06:33

 A smaller thinner PocketPi from Facelesstech:

Thinner with a simpler design but packing the same feature as before. At its heart is a raspberry pi zero W with a 3.5″ screen 480×320. It has all the GPIO pins available what aren’t being used by the screen. Its powered by a 2500mAh battery and has one full sized usb port. Its controlled by a bluetooth keyboard with trackpad

More details on Facelesstech blog.

Check out the video after the break.

App note: Color sensing improves look and feel of smart products

จันทร์, 05/20/2019 - 00:00

Renesas’ white paper on applications of RGB sensors. Link here (PDF)

Color printers also require an accurate sensor to ensure that during calibration and printing the correct amount of ink is being deposited onto the paper—an essential requirement when the target output is for color photographs.

App note: Eye safety for proximity sensing using infrared light-emitting diodes

อาทิตย์, 05/19/2019 - 20:10

A guide to human eye safety for designers of consumer products, app note from Renesas. Link here (PDF)

Active Proximity Sensing for Consumer products requires the use of a light-emitting component to illuminate the target object to be detected at some distance from the sensor. Typically, product designers do not want the illumination to interfere with the other functions of the product, or to distract the user during normal use. Therefore, Infrared Light-emitting Diodes (IR-LEDs) are used as the light-emitting components for proximity sensing. To further reduce the user awareness of the proximity function, the IR-LED and the proximity sensor are located under heavily tinted – but, infrared-transmitting – glass. While remaining unaware of any illuminating light source, the consumer indeed is exposed to low-levels of infrared radiation. All consumer products that emit light radiation – whether visible, ultraviolet, or infrared – must adhere to international standards that specify exposure limits for human eye safety.

Tiny thermocouple thermometer

ศุกร์, 05/17/2019 - 06:20

Johnson Davies built a tiny thermocouple thermometer based on an ATtiny85 measuring boiling water:

This project describes a thermocouple thermometer, capable of measuring temperatures up to +1350°C, using just an ATtiny85 and an OLED display.

More details on Technoblogy.

BLE400 with the Bus Pirate

จันทร์, 05/13/2019 - 19:00

@TheGrSpy tweeted, “Bus Pirate is talking nicely to the BLE400 from @Waveshare wearing the awesome nRF51822 SoC”

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

App note: Basics on decoupling

จันทร์, 05/13/2019 - 00:00

See AVX technical note on how capacitors filter out transients in high speed digital circuits. Link here (PDF)

This paper discusses the characteristics of multilayer ceramic capacitors in decoupling applications and compares their performance with other types of decoupling capacitors. A special high-frequency test circuit is described and the results obtained using various types of capacitors are shown.

App note: Hand soldering tutorial for fine pitch QFP devices

อาทิตย์, 05/12/2019 - 20:00

No SMD tools removal and soldering of QFP packages tutorial from Silicon labs. Link here (PDF)

This document is intended to help designers create their initial prototype systems using Silicon Lab’s TQFP and LQFP devices where surface mount assembly equipment is not readily available. This application note assumes that the reader has at least basic hand soldering skills for through-hole soldering. The example presented will be the removal, cleanup and replacement of a TQFP with 48 leads and 0.5 mm lead pitch.

Building a Raspberry Pi UPS and serial login console with tinyK22 (NXP K22FN512)

เสาร์, 05/11/2019 - 06:53

Erich Styger has been working on a UPS with the Raspberry Pi to cover a short power out:

There are different ways to ruin a Linux system. For the Raspberry Pi which uses a micro SD card as the storage device by default, it comes with two challenges:
1.Excessive writes to the SD card can wear it out
2.Sudden power failure during a SD card write can corrupt the file system
For problem one I do I have a mitigation strategy (see “Log2Ram: Extending SD Card Lifetime for Raspberry Pi LoRaWAN Gateway“). Problem two can occur by user error (“you shall not turn it off without a sudo poweroff!”) or with the event of a power outage or black out. So for that problem I wanted to build a UPS for the Raspberry Pi.

Project info on MCU on Eclipse site.