What’s inside a Dräger Multiwarn II gas detection warning system used in mining, oil, chemical, and emergency services etc to detect hazardous or explosive atmospheres.
Intrinsic safety design and how both catalytic bead and infrared IR gas detectors work, and pellistors. And a teardown of a Hydrogen Sulfide (H2S) sensor.
EEVblog #603 – Gas Sensor Teardown – Dräger Multiwarn II - [Link]
Ray Wang @ youtube.com writes:
This is Part 2 of the NeoDen Tm-240A pick and place machine demo. This time I am using it for a production run to assemble the OpenSprinkler Pi circuit board. Details can be found in this blog post: http://rayshobby.net/?p=6688
NeoDen TM-240A Automatic Pick and Place Machine Demo - [Link]
In the first of a series of videos tutorials on microphones, Doug Ford, former head designer at Rode Microphones explains the basics of how microphones work, the different types – carbon, dynamic, ribbon, condensor/electret, and how the omnidirectional pattern works. Also, the internal construction of a high end measurement microphone.
EEVblog #602 – Introduction to Microphones - [Link]
Why do digital oscilloscopes appear noisier than traditional analog oscilloscopes?
Dave busts the myth that digital scopes are noiser than analog scopes, and demonstrates what inherent advantages digital scopes can have over analog scopes in terms of true waveform capture. And also why your analog scope may be hiding important signal detail from you.
Demonstrations of how memory depth, analog bandwidth, averaging, and intensity graded displays can all effect the signal detail you see on your digital oscilloscope.
And how long exposure camera shots on analog oscilloscopes can reveal detail you can’t see with your eyes.
EEVblog #601 – Why Digital Oscilloscopes Appear Noisy - [Link]
Build this homemade “one-size-fits-most” speed controller for use with your hobby projects. It’s small, it’s flexible, and it’s built with off-the-shelf components around the venerable 555 timer IC.
Dial-a-Speed Motor Controller - [Link]
This is a review of the Sanwa PC7000 Multimeter. Video has two parts, Part1 and Part2.
Review: Sanwa PC7000 Multimeter - [Link]
In this episode Shahriar repairs an Agilent 86120B Multi-Wavelength Meter. The instrument reports “E14 Data Acquisition Problem” which corresponds to a potential internal HeNe reference laser failure. After the instrument disassembly, the old HeNe laser is removed and its optical power is compared to that of a new laser. The measurements confirm that the old laser has significantly deteriorated in output light intensity. The new laser is fitted inside the unit and the error message is eliminated. The free-space optic portion of the instrument is revealed and the principle operation is reviewed. Various components of the Michelson Interferometer is examined.
To test the correct operation of the instrument, a single tone semiconductor laser is applied to the unit and the result is compared to a different wavelength meter. The concept behind the operation of a Fabry-Perot laser is also presented before the signal is applied to the wavelength meter.
Teardown, Repair and Experiments of an Agilent 86120B Multi-Wavelength Meter - [Link]
This GU10 LED spot light is cheap (£3 including postage) and bright. But it’s also lethal! There’s a 50% chance of putting live mains within a few microns of the metal casing (which is what you’ll be holding when you insert it) and there’s no earth to protect you. It’s like playing Russian Roulette with 240v AC mains. This sort of thing gives new technology a bad name. Avoid it if you want to stay alive.
Dangerous GU10 LED Spot Light is Cheap and Bright but could Kill You – Seriously - [Link]
This video reviews the two most common reasons why the output amplitude setting on a function or signal generator doesn’t match what is read on an oscilloscope. This can be due to an incorrect attenuation setting on the scope, but is most commonly due to the fact that the generator is not presented with the load impedance that it is expecting. To correct this most common case, you can either use the correct load impedance, or tell the generator what load you are presenting it with.
Why your Function Generator’s output voltage reading can be wrong - [Link]
In this tutorial Dave explains what Operational Amplifiers (OpAmps) are and how they work. The concepts of negative feedback, open loop gain, virtual grounds and opamp action. The comparator, the buffer, the inverting and non-inverting amplifiers, the differential amplifier, and the integrator circuit configurations are also explained. Then a practical breadboard circuit to demonstrate a virtual ground and the effect of voltage rail limitations.
EEVblog #600 – OpAmps Explained - [Link]