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  1. Hero999

    change gas sensor sensitivity

    I read your post. I just don't see why i should help you when you can't even be bothered to post the schematic and datasheet.
  2. Hero999

    How to switch 3A with a mircoswitch?

    The old IRL540 will probably do but the VDS may be too high for what you're doing. Any of the following transistors will be able to switch 3A with 3V. http://www.onsemi.com/pub_link/Collateral/2SK4043LS-D.PDF http://www.irf.com/product-info/datasheets/data/irl1104pbf.pdf...
  3. Hero999

    change gas sensor sensitivity

    How are we supposed to know? You've posted no schematic and no information about the gas sensor or any of the other components you plan to use.
  4. Hero999

    How to switch 3A with a mircoswitch?

    There are plenty of MOSFETs which will switch 3A with a gate voltage of 3.7V. The old IRL540 is has an RON of 0.11Ohms at VGS = 4V and ID = 14A. With a source voltage of 3.7V it'll be a bit worse but you only want to switch 3A so it should be fine. What's the lowest battery voltage? It sounds...
  5. Hero999

    Help for a school Physic Projet ''Bulding a FM transmitter ''

    Then you need to learn more. Why not post a link to the schematic you've found so we can explain it to you.
  6. Hero999

    Help for a school Physic Projet ''Bulding a FM transmitter ''

    Audioguru designed a better transmitter while ago. Here's a link to the project. http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=15
  7. Hero999

    Circuit board inside computer power supply

    It's an RFI filter.
  8. Hero999

    Ultrasound Proximity Sensor for Blind??? Please help

    Here's a link to a very simple ultrasonic proximity detector. It works by sensing the amplitude of the reflected signal which isn't very good because it's dependany on how well the object refelects the sound as well as the distance. The output is either on or off which isn't very good either...
  9. Hero999

    Led cluster module to fibre optic interface?

    Yes, a cable gland will work. Most electrical suppliers sell them. YOu could use a small plastic enclosure for the PCB and put the fibre optics in the gland opposite the PCB.
  10. Hero999

    Help for a school Physic Projet ''Bulding a FM transmitter ''

    How are you powering the transmitter?
  11. Hero999

    Heat transfer theory

    I don't think it'll make a difference whether you use wire or resistors. A lower flow rate would certainly allow a higher temperature rise. It would be also more efficient if the air intake is non the other side of the hand so the air is recycled.
  12. Hero999

    Heat transfer theory

    I think it's worse than that. 1ft = 30.48cm 1ft3 = 30.483 = 28316.85cm3 which works out at around 1.2kW. This makes sense when you think about it. Look at the power rating of a typical hair dryer and you'll find it's in the region of 1 to 2kW. A halogen lamp will be more efficient than a fan...
  13. Hero999

    Solar charger for ZUNE 30GB mp3 player?

    It depends on how the charger works. If the actual charging  circuitry is built-in to the Zune then all you is a  power supply with a voltage of around 5.5V and a rated output current of 1.4A or more. The charger will just use as much current as it requires. The internal control circuitry should...
  14. Hero999

    Heat transfer theory

    The amount of power required is determined by the flow rate and desired temperature rise. According to Wikipedia, air  has a volumetric heat capacity of 0.00121J/cm3 under standard conditions. This means, if the flow rate is 1cm3/s the amount of power required to raise the temperature by 1oC is...
  15. Hero999

    Joining w/ external GND killing my PSU?

    You're generally better off not connecting the 0V rail to chassis because you don't know what the 0V rail of the device you're powering is connected to.
  16. Hero999

    Switch signal on pulse

    Your description is too vague. By the sounds of it you want a toggle on/off i.e. a divide by two counter rather than an XOR but it could be anything.
  17. Hero999

    HELP! how can i increase a piezo electric current?

    The circuit in question only lights the LED briefly when enough energy has been gatherd. It doesn't continuously light the LED brightly. You can't create energy from nothing, for example, there isn't a circuit which would allow a single AA cell to provide enough power to boil a kettle and the...
  18. Hero999

    DATASHEET OF SE336 (SMD IC)

    I couldn't find a datasheet but a Chinese site is selling them and provides some technical data. http://www.aliexpress.com/product-gs/447102475-IC-chip-new-SE336-wholesalers.html Perhaps you could ask them for a datacheet.
  19. Hero999

    HELP! how can i increase a piezo electric current?

    Are you just trying to power the LEDs from the transducers? If so you need to add more transducers or increase the force or speed of the mechanical action. Adding a transformer will increase the current but the voltage will be lower so may not be high to light the LEDs. You need more power. The...
  20. Hero999

    HELP! how can i increase a piezo electric current?

    Plsea post a schematic of what you already have.
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