About Test and measurement

This page contains an archive of all entries posted to Gadget Freak in the Test and measurement category. They are listed from oldest to newest.

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Test and measurement Archives

October 24, 2007

Meet Andrew's blast from the past

Back to the future

Sometimes the best way to take a step forward is to take a step back in time. So Andrew Smith designed a fully-functional toy oscilloscope, made out of parts he found in his junk box, such as the EF91, EF80 and EF184 valves. Using a DC-DC converter to power the old (but still working) 7cm CRT he discovered in his loft, Andrew housed it in the same wooden box as the rest of the circuitry. The whole system runs from a single regulated 12.6V DC supply, which can be derived from a “wall-wart” PSU. Doc Brown would be proud.

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Continue reading "Meet Andrew's blast from the past" »

November 8, 2007

Build your own DigiThermo

Return to Taking the Temperature

This link explains how to build your own DigiThermo to measure time and temperature.

DigiThermo.JPG

Continue reading "Build your own DigiThermo" »

November 21, 2007

Keep your PC cool this winter

An accurate PC thermometer you need all year round

Award-winning designer Alberto Ricci Bitti designed this simple microcontroller-free DS1621 PC thermometer that requires no calibration. It's so cheap and simple because all you need is the sensor IC, a voltage regulator and a handful of diodes and resistors. It can be plugged into any free serial port and the temperature is shown on the Windows taskbar. Lucky for us, Alberto's friends all asked for a PC thermometer of their very own, so he decided to release the build instructions into the wild. A cheap and simple PC thermometer? Now that's hot. Or should we say cool?

USB%20thermo.JPG

Continue reading "Keep your PC cool this winter" »

January 18, 2008

Richard had a flash of inspiration

Now he’s got the power to cut lightning down to size

People have always been fascinated by the fury of the heavens. Electronics prodigy Richard Hodgkinson created a lightning distance timer so he would no longer have to manually calculate the approach or retreat of a thunderstorm. He recycled a 70 KHz crystal from an old device for the oscillator. “Let there be light,” he declared as two HP 45MGC670 surface mount LEDs were attached to allow him to see measurements in the dark. And his project wouldn’t be complete without two 1.5V AA cells which are the heart of his timer. Now his creation is alive, all he needs is a wicked thunderstorm.

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Continue reading "Richard had a flash of inspiration" »

July 28, 2008

Thermal management for a frosty office atmosphere

GF US Thermal management.jpg
Thanks to Design News for this Gadget Freak, in which NASA engineer Bob Wilson takes the office temperature.

He devised a technological solution for a bureaucratic problem: convince building maintenance that his office was frigid in the morning.

By the time anyone responded to a call, the heat was on. So he programmed a TI MSP430-F2013 microcontroller to record the temperature continuously over several days.

The size of a quarter dollar and powered by a 3V lithium cell, it records converted, filtered, RL-encoded data from its built-in temperature transducer into Flash memory, to be read back later via a USB interface. The maintenance department was convinced.

Continue reading "Thermal management for a frosty office atmosphere" »

August 4, 2008

Circuit Design Idea - Microcontroller detects pulses

circuit microcontroller controls pulses.jpgTake a look at another Circuit Design Idea we have uploaded to the site.

It covers the use of a microcontroller in a nonstandard task, not just detecting a pulse but detecting it as part of a wider dozen tests and measurements.

The Design Idea begins:

While recently designing an automatic test station employing a microcontroller, I faced a nonstandard task: Detect the presence or the absence of output pulses in the DUT (device under test). You might think this task is easy to accomplish by connecting an LED to the DUT output. The blinking LED provides evidence of the pulse's presence. That approach would work if that test were the only one you needed to perform.

Continue reading "Circuit Design Idea - Microcontroller detects pulses" »

August 13, 2008

Circuit Design Idea - Amplifier holds the difference of two inputs

circuit - Amplifier holds the difference of two inputs - small.jpgCheck out another newly-uploaded Design Idea designed to give circuit building inspiration.

It involves a sample-and-hold amplifier that tracks and holds the difference of two input signals.

The Design Idea begins:

You can fulfil a requirement for sampling the difference of two signals in two classic ways. You can subtract the two input signals with an instrumentation amplifier whose output connects to an input of a classic sample-and-hold amplifier.

Continue reading "Circuit Design Idea - Amplifier holds the difference of two inputs" »

September 9, 2008

Circuit Design Idea - Illustrating low power MOSFET leakage

cc MOSFET leakage.jpgCheck out another newly-uploaded Design Idea designed to give circuit building inspiration.

It involves simple 'toggle' circuits to demonstrate the low gate leakage of modern power MOSFETs.

The Design Idea begins:
The novelty circuit in Figure 1 illustrates the extremely low gate-leakage current typical of modern power MOSFETs. You can find parts that, in a moderately dry environment, will hold their state for days at a time. In operation, if MOSFET Q1 is off, the load - perhaps a lamp or a buzzer - pulls Q1's drain to nearly the 12V-dc power-supply voltage. R2 charges C1 to practically the same voltage. 

Continue reading "Circuit Design Idea - Illustrating low power MOSFET leakage" »

October 8, 2008

Circuit Design Idea - Locked-sync sine generator

c Locked-sync sine generator.jpgHere's a Circuit Design Idea fresh to the site - Locked-sync sine generator covers three decades with low distortion (click on the circuit diagram to expand it).

It covers a sine-wave generator that can synchronise a sine-wave output through three decades of frequency and maintain low THD and constant amplitude.

The Design Idea begins:
Analogue applications, such as testing, calibration, and general system operation, often require a sine waveform of accurate amplitude and frequency, with low THD (total harmonic distortion). Some applications demand that the generator of such waveforms have the ability to accurately synchronize the output with an external timing signal.

Continue reading "Circuit Design Idea - Locked-sync sine generator" »

December 8, 2008

Circuit Design Idea - Achieve precision temperature control

Achieve precision temperature control with TEC Seebeck-voltage sampling 175.jpgHere is some more fresh Circuit Design inspiration - Achieve precision temperature control with TEC Seebeck-voltage sampling.

By periodically setting the TEC's drive to zero, a storage capacitor samples and holds the Seebeck voltage.

And you can, states the author, adapt Seebeck sampling to virtually any TEC-drive topology.

The Design Idea begins:
TEC (thermoelectric-cooler) temperature-control systems often have limited stability. The causes of these limitations are the thermal properties of the system, not the performance of the control electronics. Real-world thermal-control systems incur nonzero thermal impedances in the heat-transfer paths between the TEC; the thermal load, which is the object of thermostasis; the temperature sensor - for example, a thermistor; and the ambient temperature.

Continue reading "Circuit Design Idea - Achieve precision temperature control" »

February 13, 2009

Hotbox temperature logger

Hot Jersey.jpgHere's a great project, recommended to Gadget Freak by our own indomitable device-builder, EW's Technology Editor Steve Bush. It's the Hotbox temperature logger.

Whether its monitoring the temperature for home brewing beer, making marmalade or even checking to whether the sea water is warm enough to swim in, this logger could be the solution. No calibration required, says its inventor.

According to the website, the logger probes measure temperatures from -55°C to +125°C (-67°F to +257°F). No calibration

Here is the author's introduction:

Continue reading "Hotbox temperature logger" »

March 25, 2009

Testing circuits with toasters

testing till toast.jpg
Thanks to our sister site Design News for this Gadget Freak, which involves rewiring a toaster to make a special test chamber.

Mark Thoren and Jim Williams became frustrated when they could not get lab time to test a circuit they were designing, so they rewired a toaster to make their own test chamber

They needed to test the temperature compensation scheme of a circuit they were designing, but while their company lab had several temperature chambers they were always in use. So...
Jim grabbed a brand new toaster and plopped it down on Mark's desk, saying, "This will do." Not quite. The hysteresis of the oven's thermostat was 10C  -  too crude to measure the circuit. Mark and Jim scrounged about and found an auto-tuning temperature controller, some solid-state relays and a shiny platinum RTD probe. After some minor rewiring they had a test chamber, more than adequate and better than most of the "real" chambers that were never available when needed.

Continue reading "Testing circuits with toasters" »

July 17, 2009

Spying on your freezer to ensure it's constant and true

GF freezer monitoring.jpg
Food in your freezer should stay frozen. De-frosting and then freezing again - should power fail - is not a healthy option. But how to ensure that freezer has indeed stayed frozen?

Thanks again to our sister site Design News for this Gadget Freak, which involves a temperature monitoring system.
William Grill wanted to make sure his freezer didn't cut out and ruin his frozen food. He was concerned that when he travelled, his food could defrost and re-freeze  -  thus compromising his frozen steaks  -  without his knowledge.
So, he developed a gadget that measures freezer temperatures, keeps a history of variance and sends an alarm if freezer temperatures rise above a set range. The gadget is built around a small controller, an alarm and a temperature sensor.

Continue reading "Spying on your freezer to ensure it's constant and true" »

August 10, 2009

Circuit Design Idea - First to press the button

figire 3 first event.jpgAnother circuit idea to help get your creative juices flowing - First-event detector has automatic-reset function

It lets you indicate which game player presses a button first. Each button has a corresponding LED that indicates the pressing of the button. All other LEDs remain locked out until someone presses a reset button.
The voltage at Point A pulls down to nearly 3.7V, which you determine by adding the forward voltage of the optoisolator's internal LED, the phototransistor's voltage, and the LED's voltage: 1.3+0.6+1.8V=3.7V. The green LED then turns off.


Continue reading "Circuit Design Idea - First to press the button" »

September 29, 2009

Circuit Design Idea: Pulses indicate position

circuit schematic figure 1.jpg
A new Circuit Design Idea has been uploaded to the sight. Check it out.

It covers a simple logic circuit that counts pulses and blocks one of every 36, and is written by one Michael C Page, of Chelmsford, Massachusetts.

It begins:

Continue reading "Circuit Design Idea: Pulses indicate position" »

October 30, 2009

Video: MCU turns the gears of time



Check out this inventive use of an MCU and stepper motor by one Alan Parekh.

This great looking gear clock tells the time in a unique way. A PIC 16F628A microcontroller with an external 20MHz crystal oscillator times a stepper gear, which drives a minute display, which also drives an hour display...

It's 11:21 in the still above, by the way.

Details of Alan's project can be found here: http://alan-parekh.com/projects/gear-clock/

Of the motor, he writes:

Continue reading "Video: MCU turns the gears of time" »