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    Electronics-Lab.com team is always looking for partnerships that will benefit our members and bring some valuable offer to all of you. This time we would recommend an Elektor yearly subscription for half the normal price. With this offer you will gain access to thousands of articles and hundrents of projects. This is an exlusive offer for electronics-lab members and to benefit from the offer you just have to enter E-LAB16 code on this form. The offer is valid for Elektor GREEN Membership and costs US $37.50 (€34.00 / £24.48) for a year.

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  2. Hi and welcome to the forum,

    For what you describe you will need a light activated switch like this one: http://www.electronics-lab.com/project/light-and-dark-sensitive-switch/

    This switch has adjustable sensitivity and with a little of experimentation you will manage to get the desired effect. It may be needed to add a kind of filter to the light sensor to reduce it's sensitivity even further as you need the switch to be activated in direct sunlight. You can also think to add a small "light pipe" to achieve the desired functionality.

    Hope that helps.

  3. Here are two SPICE models found online that will simulate the main IC functions including:- a) bar/dot mode selection, B) dot mode carry for cascaded ICs, c) resistor-programmed hi/lo reference voltages, d) output current selection, e) non-grounded V- and divider ladder, f) independent V+ and Vled, g) leakage current of outputs, h) segment overlap and i) supply current variation with V+ and Vref output load.

    This model is build by user "alec_t" at electro-tech-online.com forum.

    LM3914.zip

    LM3914asc.zip

  4. Hi,

    2SD613 NPN has replacement BD243C, BD543C, BD801, 2SD866 BD243C KT819G

    2SD633 is a NPN Darlington transistor and has replacement BD649, BD901, BDW73C, BDX53C BD649

    2SD600 has replacement BD139, BD230, BD379, 2SD1684 BD139

    2SB631 has replacement BD140, BD231, BD380, 2SA1184 BD140

     

     

  5. According to Sensirion datasheet here SHT31-ARP-B is an analog output temperature and humidity sensor with linearized and calibrated output. To interface it with Arduino you will have to measure the output voltage using an Arduino analog input and then convert the reading to humidity or temperature value based on the linear formulas found on the datasheet. These formulas are depended on the supply voltage of the sensor.

    I also found an Arduino library for this sensor here: https://github.com/winkj/arduino-sht you may find it useful.

  6. Sure it can be, you only have to feed an AC signal to it's input (form a transformer for example) and measure it's output using an oscilloscope. Oscilloscope probe and input will provide some load to the rectifier and thus you will be able to see the full wave rectification and determinate if the bridge is working.

  7. You could build a single cell LED boost driver like the third schematic here, using only 2 transistors. Or you can use ZXSC310 IC to build a boost LED driver working for as low as 0.8V input voltage like this schematic here: http://www.homemade-circuits.com/2012/05/1-watt-led-driver-circuit-using-single.html

    Alternative you can build a 1.2V to 5V boost DC-DC converter able to provide 1A max output current, like the second schematic here.

    For drained AA and AAA batteries you can build a Joule Thief that is able to draw the last available juice from the almost dead batteries. Like the first schematic here.

    http://www.homemade-circuits.com/2012/01/how-to-make-simplest-15v-bluewhite-led.html

    LED Driver (1).png

    HB-LED-for-Li-Battery-Operated-Systems1-1383181219.png

    Two-Transistors-Single-Cell-Battery-LED-Driver.gif

     

  8. I am suggesting to have a reader in place where the pieces will be placed and each piece will have an RFID tag attached. So when the piece come close to the reader it will register itself. Each RFID has it's own ID and will not interfere with each other piece and will interact with the reader only. The only issue i see is if one piece is placed in the range of the reader and another piece is coming in. In this case maybe the reader maybe gets confused, but this is something to be tried.

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