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Posts posted by mixos

  1. I came across bq24100 datasheet and i thought it may interests you. This is a Li-Ion switchmode charge management IC. Take a look here:


    In page 25 of datasheet there is circuit using bq24100 that charges the battery while powering the system without affecting battery charge and termination. Search for other charge ICs that you could be used this way.

  2. As electrolytic capacitors getting old their ESR (Equivalent Series Resistor) is rising and that may or not cause problem to your circuit.

    You can measure ESR using special ESR meters (Elektor has published one before) or using low resistance meters. An alternative method if you don't like any of the above is described here:


    The quality it's for sure a reason for a capacitor to fail but also enviromental conditions or excess heat can dry out a capacitor. I think it's difficult to predict the lifetime of an electrolytic capacitor so some may last much more than others.

  3. Inplug it from the rest of the circuit and mark the side used as secondary (the side that goes to outlet and gives 220VAC). Then with a multimeter measure across the terminals of each side to find the two separate coils (use contiunity tester). Your transformer will look like the one in the image below. It must be T2 in schematic (....-sxems.pdf). Then short the two terminals so you have one coil each side of the transformer and two free terminals. Then with EXTREME CARE apply 220 AC on the secondary winding and measure the voltage on the primary.

    Then you can find the ratio dividing the two voltages 220/what you measure on primary. The most possible rating of your transformer is 2x120VAC on secondary and 2x12VAC on primary so you must measure 24VAC on primary (when you short the coils).

    The power of it must be at least 400VA on the one and 600VA on the other. Check the size of each transformer if are identical. If they are the same then they are 600VA both of them otherwise the bigger -> the most powerfull, .

  4. Hello :D

    This is the main power transformer that steps up the low AC voltage to a higher level AC volatge (110VAC or 220VAC). This has usually a ratio 1:10 between primary and secondary windings and can be used also as a step down tranformer if you use it in reverse.

    How many terminals can you see on this tranformer?

  5. After exposure you should develop the board in NaOH solution. The solution must have aroung 5,8g per litre of water. After 1-2 minutes you will se the pcb artwork to appear on the board. Wait until it seems clearly. After this step you move to etching step as normally on no photo fabrication method.

  6. Ever wonder what's lurking within the dark corners, nooks and crannies of your computer? Is some gremlin responsible for all those crashes---you know, the ones that happen when you are trying to save that critical document you've been working on so diligently for the past three hours? We wondered too, so we took a look to see what we could find. And guess what? When we put the computer chips under the microscope we found some very interesting creatures hiding there.

    Hewlett-Packard superscalar PA-RISC 7100LC Hummingbird microprocessor chip

    Their search has led to a new collection of photomicrographs (photographs taken through a microscope) featuring many of the interesting silicon creatures and other doodling scribbled onto integrated circuits by engineers when they were designing computer chip masks. The tiny creatures are far too small to be seen with the naked eye, so we have provided high-magnification photomicrographs to share these mysterious wonders with our visitors. Engineers designing modern computer chips have a very rich sense of humor as you will discover when you visit our Silicon Creatures Gallery that we keep corralled in the Silicon Zoo. We hope you enjoy your adventure!

    Source: http://www.microscope.fsu.edu/creatures/index.html

    Also downlod this great screensaver: http://www.microscope.fsu.edu/software/screensavers/zoosaver.html

    More interesting microscope images here: http://www.microscope.fsu.edu/micro/gallery.html

  7. You must start by identifing the magnetic compass sensor you will use. Some common sensors are:

    KMZ52 from Philips
    HM55B from Hitachi
    1490 Compass Sensor

    Then you can take a look to some schematics/application notes to see how this can be intergrated to your system:

    1490 Digital Compass

    Electronic Compass Design using KMZ51 and KMZ52

  8. A virtual scanning electron microscope (SEM) on your PC!

    Check out this great software and watch as close as you couldn't imagine into chips, flyes, rocks, ect. Hope developers release more data in future.

    Texas Instrument DLP (Digital Light Processing) chip

    Virtual Lab completely emulates a scanning electron microscope and allows any user to zoom and focus into a variety of built-in microscopic samples. It also comes with a set of educational materials such as a demo on how a SEM works and movies of the real thing in action.

    An integrated circuit (TI jm38510 series NAND gate)

    Virtual lab allows users to pan around a sample and zoom up to 3,600 x magnification. There are also controls to control focus, brightness, and contrast. It effectively simulates a real SEM's set of controls. It serves as a very accessable alternative compared to the costs of purchasing and setting up a real Electron Microscope.

    Download it : http://learn.arc.nasa.gov/vlab/install/VirtualLab-pc.zip

    more info: http://learn.arc.nasa.gov/vlab

  9. Hello :D

    You can find some Soundcard oscilloscopes software that require no hardware to be attached to the pc. You need only one sound card and some connectors to drive the signal at the input of the sound card of your pc.
    Check here: http://www.electronics-lab.com/downloads/pc/index.html

    Additional pc oscilloscopes:

    Non Commercial
    http://www.geocities.com/tangmonster911/oscilloscope.htm (ISA bus)
    http://www.dansworkshop.com/Homebuilt%20oscilloscope.shtml (TV based)
    http://www.geocities.com/SiliconValley/Lakes/7156/articl3.htm (with LEDs)
    http://www.electronic-projects.net/Electronic-Projects/projects/telescope/index.shtml (TV based)
    http://www.intio.or.jp/jf10zl/tvosc.htm (TV based)

    http://www.usb-instruments.com/ (USB)

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