App note: 400MHz, 2500V/µs, 9mA single/dual operational amplifiers

in app notes by DP | 1 comment


400MHz, 2500V/µs, 9mA single/dual operational amplifiers (PDF!) application note from Linear Technology:


  • 400MHz Gain Bandwidth Product
  • 2500V/μs Slew Rate
  • –85dBc Distortion at 5MHz
  • 9mA Supply Current Per Amplifier
  • 6nV/√Hz Input Noise Voltage
  • Unity-Gain Stable
  • 1.5mV Maximum Input Offset Voltage
  • 8μA Maximum Input Bias Current
  • 800nA Maximum Input Offset Current
  • 40mA Minimum Output Current, VOUT = ±3V
  • ±3.5V Minimum Input CMR, VS = ±5V
  • Specifi ed at ±5V, Single 5V Supplies
  • Operating Temperature Range: –40°C to 85°C
  • Low Profi le (1mm) TSOT-23 (ThinSOT™) Package

The LT®1818/LT1819 are single/dual wide bandwidth, high
slew rate, low noise and distortion operational amplifi ers
with excellent DC performance. The LT1818/LT1819 have
been designed for wider bandwidth and slew rate, much
lower input offset voltage and lower noise and distortion
than devices with comparable supply current. The circuit
topology is a voltage feedback amplifi er with the excellent
slewing characteristics of a current feedback amplifi er

A real-time table tennis score keeper

in hacks by DP | 0 comments


A real-time automatic table tennis score keeper by Pol, Frank, and Taylor from Cornell University, built as a final project:

The primary goal of this project is to use digital signal processing on a video feed to track a ping-pong ball in a game of table tennis. We propose that by tracking the movement of a ball, a processing system is able to maintain the state of the game, and determine the score in real time with no direct user input. This allows players to focus on their performance, without breaking the flow of the game to recall the score, or determine who should be serving.
The system that we have designed uses this type of ball tracking and understanding of gamestate, and superimposes the score of the game on top of a video stream of the game in action, so players can easily see it while playing. Additionally, it provides an indication to players of who should be serving, and provides audio feedback for certain states of gameplay– such as scoring or serving– to provide an augmented table tennis experience.

Via the contact form.

Check out the video after the break. Continue reading →

ESP8266 WiFi touch screen thermostat

in Arduino, wireless by DP | 1 comment


An instructables on how to build WiFi touch screen thermostat by EasyIoT:

In this tutorial we will show how to build WiFi controlled thermostat with ESP8266, Arduino and touch screen display. Thermostat will also show other info, like weather forecast and temperature outside. Total cost for thermostat is about 40EUR, which is price for basic commercial thermostat in shop.
Basic features:

  • 6 modes – Auto, Off, LOLO, LO, HI, HIHI
  • Touch screen
  • WiFi connected
  • Four set temperatures (LOLO, LO, HI, HIHI) and weekly schedule
  • Time display
  • Additional data display – temperature in other room, air pressure and weather forecast

Project info at

Check out the video after the break. Continue reading →

Free PCB coupon via Facebook to 2 random commenters

in Free PCBs by DP | 2 comments


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 →

Posted in Free PCBs | Tagged | 2 Comments

Universal soldering controller

in project logs by DP | 0 comments


sparkybg shared his universal soldering controller in the project log forum:

The intention was to build the most universal soldering controller I can think of. It can drive any low voltage (upto 24V) iron with thermocouple or resistive sensor, in series with the heater, or separate.
Here is a short list of features:
– power: 9-28V, AC or DC
– 2 separate heater control channels
– 2 independent sensor inputs
– current source on any sensor input 3uA – 12mA, wuth 2 bands (x1, x16) and 256 steps per band
– flexible differential amplifier input selection
– amplifier gain from 0 to 750 in 256 steps
– negative offset selection in 1024 steps
– resistive instrument identification (upto 625 different instruments can be identified by 2 resistors on the connector)
– polynomial floating point voltage/resistance to temperature calculation
– wave shaping to filter out the inductive peaks from series sensor signal
– PID control with power limit
– isolated USB port for firmware updates and live data
– 128×64 OLED display with rich user interface.

Via the forum.

ESP8266 Breadboard adapter

in wireless by DP | 2 comments


Baoshi of DigitalMe wrote an article detailing his ESP8266 (ESP-07/12) Full I/O Breadboard adapter, that is available at Github:

The rise of the ESP8266 WiFi chip was almost overnight with Espressif’s open approach and pushing from Hackaday. While no ground-breaking product has yet emerged, the development on the chip are phenomenon. However due to an unknown reason the ESP8266 modules manufacture seems to prefer non-standard 2.0mm pitch connector, which gives a lot of headache to breadboarding lovers like me. This forced me to make a breadboard friendly ESP8266 breakout board.
The modules I’m targeting are ESP-07 and ESP-12, both having identical pinout but only differ in antenna type. I choose these two because they have all the I/O available, and using same edge castellation (half vias) connectors which is easy to work with.

Project info at DigitalMe site.  It’s also up on Tindie.

Posted in wireless | Tagged , | 2 Comments

Interfacing PIR sensor to 8051 microcontroller

in Interface, sensors by DP | 4 comments


Praveen from CircuitsToday has written up an article on interfacing PIR sensor to 8051 microcontroller:

PIR sensors are widely used in motion detecting devices. This article is about interfacing a PIR sensor to 8051 microcontroller. A practical intruder alarm system using PIR sensor and 8051 microcontroller is also included at the end of this article. Before going in to the core of the article, let’s have a look at the PIR sensor and its working.

Mikey’s first DirtyPCB experience

in, PCBs by DP | 0 comments


Mikey shares his first impressions with DirtyPCBs:

Yes, exclamation mark and lots of yelling!
The PCB’s has arrived, lets have a look at them.
At first glance they look very good, silk screen is fine, both on top and bottom. The outline of the board feels smooth with a sharp edge, just as it should be.
Let’s have a closer look…

Details at

3D model .STL to .PNG preview

in #liveupdates, site by Ian | 4 comments


Bing search sucks.

Tried a bunch of ways to get image previews from 3d model .STL files. OpenSCAD does a decent and fast preview, but you gotta figure out where to put the camera for a good scene. The Linux repositories with OpenSCAD are outdated so you have to compile from source. Fire it up and it needs an Xserver and OpenGL, which are an additional install on most servers.

Looked at stl2pov, used by thingiverse to go from .stl->.pov and then render with the open source POV-Ray. From there to stltools, an improved version in Python. Renamed incorrectly named files, installed Numpy dependencies, couldn’t get it going.

Completely by accident found libre3d/render-3d which rolls all of the above into a .PHP script we can run server side. It coverts .STL to .POV using techniques similar to stltools, adds grid and calculates a camera position, then renders it through POV-Ray. Exactly what we would have cobbled together, eventually. Thanks Open Source!

Windows boxes running XAMPP are my go to for web development. Installed POV-Ray and got the render-3d scripts by composer. Worked on first try, but POV-Ray stayed open and blocked the script from finishing, a common issues running Windows app with a GUI from PHP. Around line 51 of Povray.php tag an /EXIT onto the POV-ray execution options to force shutdown: $cmd.= ” /EXIT”;.


render-3d doesn’t actually do well with our test model. The camera position isn’t very well chosen, but that’s something we can work on later. The rendering looks much nicer than OpenSCAD.

Bing, you suck. Google would have given modern relevant results first, not ten pages into a vaguely related search.


Posted in #liveupdates, site | Tagged | 4 Comments

#FreePCB via Twitter to 2 random RTs

in Free PCBs by DP | 0 comments


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.

Talk SPI to EEPROM part3: Test SPI Protocol with Bus Pirate

in Bus Pirate, testing by DP | 0 comments


Jan Cumps tested out SPI Protocol using a Bus Pirate:

It wasn’t my initial intention to use the Bus Pirate.
But my first naive attempts to talk from Hercules to EEPROM failed.
I could create the SPI instructions with the LaunchPad, but I didn’t get a reply back from the 25LC256.
It’s in these cases that a Bus Pirate comes in handy. It’s easy to prototype a SPI conversation from the Pirate’s command prompt.

Details at Jan Cumps’s blog.

Arduboy – card sized gaming

in Arduino, open source by DP | 8 comments

The final Arduboy, an Arduino gaming and learning project, came out yesterday. Kevin has been in Shenzhen arranging manufacturing for the last few months. He’s also been a staple at the neighborhood BBQ place and Hacker Camp after parties, some of us even got access to pre-release dev-kits.

Of all the project builds I’ve witnessed in Shenzhen, Arduboy stands out as the best example of what you can do here in a short time if you’re well prepared and have a reasonable project scope. Kevin landed ready to go, with electronics and (most) mechanical design complete. In China he refined Arduboy for production with the help of his local manufacturing partners. The result is excellent. Congratulations Kevin!

You can visit his Kickstart page for more info.

Simple Infrared PWM on Arduino

in Arduino, infrared by DP | 3 comments


The crew from AnalysIR has written up an article on Simple Infrared PWM on Arduino. This first part of a series will show you how to generate the simple Infrared carrier frequency on Arduino:

We are often asked on discussion boards, about conflicts between IRremote or IRLib and other Arduino Libraries. In this post, we present a sketch for ‘Simple Infrared PWM on Arduino’. This is the first part in a 3 part series of posts. Part 1 shows how to generate the simple Infrared carrier frequency on Arduino, using any available IO pin and without conflicting with other libraries. Part 2 will show how to send a RAW infrared signal using this approach and Part 3 will show how to send a common NEC signal from the binary or HEX value

Posted in Arduino, infrared | Tagged , | 3 Comments

Power Meter pulse logger with ESP8266 running NodeMCU

in wireless by DP | 0 comments


Patrik Thalin writes:

This device is installed in my home to monitor the usage of electricity. It counts the pulses from the meter and produces a log file with number of pulses and a time stamp that can later be analyzed. The hardware is quite simple. The NodeMCU development kit board with an ESP8266 running the NodeMCU firmware is connected to a phototransistor with an pull-down resistor. The firmware and my lua script seems stable since it has been running for more than 10 days without problems.
The phototransistor used is PT204-6C. It is aimed at the pulse windows on the power meter.

Via the contact form.

Project info at Patrik’s blog.

Posted in wireless | Tagged , , , | Leave a comment

Teardown, repair and analysis of an Anritsu MS2721A 7.1GHz portable spectrum analyzer

in repair, Teardowns by DP | 0 comments

Teardown, repair and analysis of an Anritsu MS2721A 7.1GHz portable spectrum analyzer by Shahriar of TheSignalPath:

In this episode Shahriar takes a look at an Anritsu MS2721A portable spectrum analyzer which does not completely boot up. After displaying the message “Application Running!” the unit no longer advances to the main measurement screen. After intentionally corrupting the firmware, a system menu is observed.
During the teardown of the unit, various DC-DC converters are examined along with a basic overview of the Linear Technologies DC-DC converter datasheet. The main problem is traced to a faulty SRAM IC. After replacing the IC the unit completes the boot process. Various simple experiments are performed to ensure the unit’s functionality and correct operation.

App note: Advanced vibration alerting waveforms

in app notes by DP | 0 comments


Here’s an app note from Precision Microdrives on different techniques of motor vibration that can be used as haptic feedback. Link can be found here

Advanced signal waveforms are predominantly used in haptic feedback, but in fact the effects of simple vibration alerting can be greatly improved with relative ease. With vibration alerting the output waveform need not be restricted to just a continuous vibration, we will cover three simple techniques that can be used to extend the capability of a vibration alerting system, without implementing fully a haptic feedback solution.

Free PCB Sunday: Pick your PCB

in Free PCBs by DP | 63 comments


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 →

Posted in Free PCBs | Tagged | 63 Comments

App note: Discrete driver circuits for vibration motors

in app notes by DP | 0 comments


Simple solution in driving vibration motors, an app note from Precision Microdrives. Link can be found here

This bulletin covers the circuitry required to drive vibration motors from a high impedance signal source (for example an output pin of a micro controller / digital device).
There are several integrated IC’s that can do this job, but if there is already a power supply of appropriate voltage in the application design, it is often cheaper to use discrete components.
Circuits like this are common in handheld applications where one may want to alert users and operators of an event. This is generally known as vibration feedback. For haptic feedback which is used more commonly with things like touch-screen interfaces, a more advanced drive circuit is usually employed.