by BasinStreetDesign @ instructables.com:
I had a bunch of random inductors in some random drawers and I wanted to know what values they were. These values are quite often not obvious by looking at the device. Colour codes for old ones were not standardized and some of the coloured rings on inductors can be faded or discoloured so that its impossible to tell what they are. Others may be unmarked and any that are hand-wound are just guess work without a meter. So I decided to make an inductance and capacitance meter which would be fairly accurate and work over several decades of value from a few nano-Henries to a few milli-Henries and also from a few pico-farads to about a micro-farad (hopefully). Sounded easy – what could go wrong?
Inductance/Capacitance Meter Saga - [Link]
By Ben Coxworth @ gizmag.com:
Ever since the Fukushima nuclear reactor disaster, there has understandably been an upsurge in the sale of consumer radiation-detecting devices. Most of these gadgets are variations on the Geiger counter, in that they alert the user to the presence and level of radiation, but not the type of radiation – which is very important to know. Researchers at Oregon State University are hoping to address that situation, with the MiniSpec. Currently in development, the handheld device will additionally tell its users what type of radionuclide is creating the radiation, and whether it poses a risk.
Small, portable and cheap radiation detector is being designed for the public - [Link]
An old but interesting app note (PDF) from Microsemi on resistorless current-sensing technique. [via]
This application note introduces a simple current-sense technique that eliminates that sense resistor, resulting in system-cost reduction, PCB space saving, and power efficiency improvement. Furthermore, the new current sensing mechanism allows higher dynamic tripping current than the static one (built-in low-pass filtering) to improve current-sense noise immunity.
A simple current-sense technique eliminating a sense resistor - [Link]
Pulse oximetry is a non-invasive method for monitoring if a patient’s oxygenation is unstable and Arduino user die_Diode sent us his version of a DIY Pulsoximter developed with two Arduino:
Arduino Mega for the oximetry electronics and Arduino Uno for the graph. The electronics includes LED Driver, Photo current transformation, patient-dependent calibration LED, Active filters, Nellcor SpO2 sensor. Adafruit OLED displays Vitalparamter. Noritake VFD display GUU-100 shows the PPG. The boards are connected to the electronics with a Protoshield.
DIY Pulsoximeter developed with two Arduino - [Link]
by Henrik’s Blog @ hforsten.com:
Ionizing radiation is something that almost anyone finds exciting (or scary) and I’ve also been for long wanted to build a Geiger counter. Unfortunately Geiger tubes have usually been too expensive to seriously consider buying them just for a hobby project. But I found out that sovtube sold soviet cold war era Geiger tubes only for a couple dollars. I bought one CI-22BG tube and one CI-3BG tube for total of 16€ including shipping from Ukraine to Finland. The site itself didn’t really convince me payment via Paypal failed because of invalid seller email address and gmail warned me that order confirmation e-mail might not have come from the address it claimed. However, I got both of the tubes and they seemed to be okay.
DIY Geiger counter - [Link]
Here’s a cheap and simple Laser Power Meter LPM for small power source, based on “MarioMaster LPM meter” by Davide Gironi:
This type of meter uses a ThermoElectric Cooling module (TEC) to measure the power of a laser. The TEC will absorb the laser light, and transform the heat generated by the laser beam to an electrical signal.
An operational amplifier is used then to amplify the signal and ouput it to a volt meter.
Voltage meter will display the power in W unit of the laser beam you are testing.
The TEC takes a little amount of time to heat, so wait until your reading became stable.
This type of meter is simple and cheap to build.
It can measure laser power up to 2W, with an accurancy of +-10mW.
A cheap and simple Laser Power Meter LPM for small power source - [Link]
Here we have it – an affordable Open Source Laser RangeFinder – OSLRF-01 from www.lightware.co.za. You can order it fully assembled and working or just PCB and optics (all other components have to find by Yourself).
An Arduino Based Laser Rangefinder - [Link]
Dave teardown 3 classic analog multimeters:
EEVblog #634 – Analog Multimeter Teardowns - [Link]
by Ryan Roderick, Intersil @ edn.com:
The fundamentals to translating the analog world into the digital domain reduces to a handful of basic parameters. Voltage, current, and frequency are electrical parameters that describe most of the analog world. Current measurements are used to monitor many different parameters, with one of them being power to a load.
There are many choices of sensing elements to measure current to a load. The choices of current sensing elements can be sorted by applications as well as the magnitude of the current measured. This write up is part one of a three part series that discusses different types of current sensing elements. The focus of this paper is evaluating current measurements using a shunt (sense) resistor. The paper explains how to choose a sense resistor, discuss the inaccuracies associated with the sensing element and the paper discusses extraneous parameters that compromises the overall measurement.
Sensing Elements for Current Measurements - [Link]
Check out the project page for ongoing development for emonPi Raspberry Pi Energy Monitoring Shield, on OpenEnergyMonitor. (Also follow the posts on the project blog here.)
For a while now I have been working on developing a Raspberry Pi energy monitoring shield. Here is a preview of the first prototype design.
The emonPi is not designed to totally replace the emonTx V3, but rather to complement it. I see the emonPi fulfilling two applications:
As a low cost Raspberry Pi add-on shield to make all-in-one home energy monitoring unit based on the Raspberry Pi. We will produce a version of the emonPi board on it’s own (without enclosure, HDD and LCD), maybe even with just SMT components ready assembled (like the Arduino Lenoardo) to being the cost down further.
As a high quality, robust and nicely enclosed stand-alone energy monitoring unit and web-connected base station with LCD status display, built in hard-drive for local logging and backup. The emonPi has also been designed to be perfect for installers of heat-pump monitoring systems which require many temperature sensor wired up (see temperature sensing part of my forum post update) as well as power monitoring.
The emonPi has got an option for RFM12B / RFM69CW radio to enable it also to act as an emonBase, receiving date from other wireless nodes such as emonTH (room temperature and humidity node), emonTx V3 (energy monitoring node) and transmitting the current time to the emonGLCD LCD display.
Since the emonPi is an energy monitor sensing node and remote posting base station all-in-one and coupled with a status LCD this should make system setup, installation and debugging easier. The emonPi should also be great for remote administration since with the correct network config the Raspberry Pi can be accessed remotely, log files checked and even upload Arduino sketch firmware onto the emonPi’s ATmega328….
emonPi Raspberry Pi Energy Monitoring Shield - [Link]