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23 Apr 2012

Very cheap low-speed dual channel PC/USB oscilloscope with STM32 (STM32F103C8T6)  microcontroller

Miniscope v2c is a very simple USB interface for low-speed oscilloscope/recorder capable with continuous sampling and streaming to PC at 2×300 kSps speed. It is stripped down from switchable analog amplifier that version v2b had, but it is using small single-side PCB that would be easy to make with toner transfer method and parts should cost less than $10 total.

Miniscope v2c – Cheap low-speed dual channel USB oscilloscope with STM32 – [Link]

20 Apr 2012

Monitoring your Air Quality. Chris writes – [via]

With allergies and asthma I’m interested in both the indoor and outdoor air quality. I heat with a Quadrafire woodstove. It is suppose to be a clean stove. I was interested in the impact on both my inside air (ie. ash/dust) and outside air (smoke). New York State monitors the air quality at several locations around the State. Certified Allergy & Asthma Consultants in Albany NY published daily pollen counts. I have several weatherstations collecting data ( KNYREXFO1 [barn roof], KNYCLIFT1 [garage roof]),

There are several citizen group projects that are developing open source equipment (e.g. Air Quality Egg). There are several recent discussions about adding a Particulate sensor. The Egg Project aims to give citizens a way to participate in the conversation about air quality. It is composed of a sensing device that measures the air quality in the immediate environment and an on-line community that is sharing this information in real-time. It is a community-developed, open source project that is driven by people who care about the air they breathe.

The $290 DC1100 Pro Air Quality is a true Laser Particle Counter with two different size ranges. The small channel (0.5> Micron) should see bacteria and mold. The Large channel (2.5> micron) should see dust and pollen. The LCD display constantly shows bargraphs and values for the small and large particles. The unit saves 30 days of air quality data. I ordered the unit with the PC Interface Option and connected it to an Arduino Ethernet so I can automatically log the data to Pachube. That way air quality alerts can be triggered and sent to twitter and my cell phone.

Monitoring your Air Quality – Automatically measuring and graphing Air Quality – [Link]

20 Apr 2012

Le Hung writes:

LCFesR 4.0 unit is a precise, wide range LC / LCF / LCR / ESR meter (tester / checker) that measures inductance (L), capacity (C), frequency (F), small resistance (R) and equivalent series resistance (ESR) of a capacitor inside an electronic circuit (in-circuit). The meter can be built easily with one- or double-sided PCB and available electronic components (DIY). It’s functions are base on an further developed AVR ATMega88PA-PU microprocessor. Professional KIT is also available.

LCFesR 4.0 meter – LC / LCF / LCR / ESR meter – [Link]

17 Apr 2012

OpenLog is an open source data logger. Simple to use, simple to change. We wanted to create a serial logger that just worked. Power up this device and it will start logging any received serial data at 9600bps. Sending Ctrl+z three times will drop out of logging and in to command mode. ‘new’ will create a new file. ‘md’ makes a directory. ‘?’ brings up the list of commands. OpenLog doesn’t do a lot, but it does log serial streams extremely well.


  • >new testfile.txt
  • >append testfile.txt
  • <(send large amounts of text followed by three ctrl+z characters)

That’s really it! OpenLog firmware is open source and is based on Bill Greiman’s sdfatlib. OpenLog currently supports FAT16 and FAT32 microSD cards (we’ve tested up to 16GB!).

OpenLog – an open source data logger – [Link]

17 Apr 2012

Measuring Battery Capacity with an Arduino. Dennis writes- – [via]

I needed a couple of AA batteries and found the display at the supermarket where they were all arrayed. Normally when I’m shopping in the supermarket, I tend to look at the price/kg or price/l when comparing similar products. In the case of the batteries, there was no such indicator. Fine, I thought, I’ll work it out myself. I grabbed a few different makes and scanned the packaging for some measure of their capacity. Nothing. Not a single one of the batteries had any indicator of how much energy they would provide. Instead, they all had terms like ‘PLUS’, ‘SUPER’, ‘ULTRA’ and of course had wildly differing prices. So, I decided that it was time for an experiment and bought one pack of every type I could find.

Measuring Battery Capacity with an Arduino – [Link]

17 Apr 2012

Arduino Temperature Humidity Sensor @ PlastiBots – [via]

The projects I do tend to fall in one of two buckets – either proof-of-concept (so I can learn new stuff) or items that have some sort of functional use. The need for this project came about when my wife was prodding me about the humidity in the house and whether our humidifier was doing it’s job correctly. Most people would just go out and buy a temp / humidity sensor and be done with it. However, if you have a look around here, you will see that I don’t fit that mold. Instead, I decided to build an accurate temp / humidity sensor with a Sensiron SHT11 to read the values, a RBBB Arduino kit to process everything and an Adafruit 128×32 OLED to display the results – all wrapped up in… LEGO! Read on for more…

Arduino Temperature Humidity Sensor – [Link]

6 Apr 2012

dangerousprototypes.com writes:

Ben Eishen sent in this link. He says, “I have been thinking about building an ESR meter, and this one looks like a winner.” The design is based on the ATMega88 and according to the designer, Dr. Le Hung, “The LCFesR 4.0 unit is a precise, wide range meter that can measure inductivity, capacity, frequency and equivalent series resistance of a capacitor in-circuit, which can be easily built with homemade one- or double-faced PCB and available electronic components.” The video above shows the LCFesR measuring component values as compared to values determined by a commercial unit.

The schematic and documentation can be found on Dr. Le Hung’s website.

ATMega88 based LCFesR meter – [Link]

6 Apr 2012

Air Quality Egg by @EdBorden — Kickstarter – [via]

The Air Quality Egg is a sensor system designed to allow anyone to collect very high resolution readings of NO2 and CO concentrations outside of their home. These two gases are the most indicative elements related to urban air pollution that are sense-able by inexpensive, DIY sensors.

Air Quality Egg – [Link]

30 Mar 2012

Safecast Geiger Counter Reference Design @ bunnie’s blog. [via]

Safecast Geiger Counter Reference Design – [Link]

29 Mar 2012

Build a circuit that displays four channels 0-100C using Pt100 as the temperature sensor. Wichit Sirichote writes:

The RTD or the Pt100 is one of the high accuracy temperature sensor for laboratory. Using the high resolution delta-sigma converter, enables designer to use a simple voltage divider circuit for measuring the resistance of the RTD without the need of any DC amplifications. This instrument shows how to use the LTC2420, 20-bit delta-sigma converter and the LM385 reference voltage for measuring four Pt100 sensors and displays on the text LCD.

4-Channel Pt100 Thermometer – [Link]





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