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  1. Hero999

    What are Solder Pots used for

    I wouldn't recommend acid flux. Use rosin cored flux which is found in normal solder and use sparingly.
  2. Hero999

    Please help - OLED "Glow strip" for Motorcycle Helmet

    Most glues are only poisonous before they've cured as they have water soluble components or give of poisonous gasses. Once set most adhesives are fairly inert and therefore safe. My advice is speak to tha manufacturer.
  3. Hero999

    Please help - OLED "Glow strip" for Motorcycle Helmet

    The power supply is pretty small. I've got one and it measures around 10x15x25mm from memory. Don't worry about the relatively high voltage, it's low current and high frequency so the shock hazard is minimal. It looks like this is easy to do but difficult to do well: don't forget the whole...
  4. Hero999

    The voltage varies under load. How can I use a Voltage comparator?

    Yes, use Thevenin's or Norton's theorem to calculate the equivalent series resistance of the dynamo and use Ohm's law to calculate the current through the LED. Look at the data sheet. It should tell you the operating voltage range and change in LED current vs supply voltage.
  5. Hero999

    PA HELP NAMAN PO SA THESIS NAMIN

    I have a good mind to delete this thread but I'll let it stay for now. If you want help please: Post in English, few people here understand the language you've posted in. Do not post in BLOCK CAPITALS, it's considered to be shouting and is very rude. Do not simply ask for us to do your project...
  6. Hero999

    ELECTRONIC BILLBOARDS

    Then it looks like you've answered your question: it's not economically viable to use an electronic billboard. Besides, I don't believe you when you say you've done the research, otherwise you wouldn't need to have asked the questions in your previous post. Care to post what research yo've...
  7. Hero999

    The voltage varies under load. How can I use a Voltage comparator?

    Have you tried reducing the the load resistance or short circuiting it? It could be that your dynamo gives a constant current output rather than a constant voltage output above a certain speed. If the voltage changes widely as the resistance is changed but remains constant above a certain speed...
  8. Hero999

    Please help - OLED "Glow strip" for Motorcycle Helmet

    Is it just a light or a propper display? You can get electroluminescent panels which do this kind of thing. They require an inverter to convert the DC battery voltage to 100V AC at a few kHz but the good news it can be bought off the shelf.
  9. Hero999

    ELECTRONIC BILLBOARDS

    Why are you asking this? How much research have you done?
  10. Hero999

    Laptop Battery rebuild

    Please post in English.
  11. Hero999

    The voltage varies under load. How can I use a Voltage comparator?

    The zener will stop the battery from overcharging and I assumed you wanted to charge a lead acid battery, not NiMH which is more difficult to charge. How fast can you cycle? When I was really fit I used to be able to reach speeds of up to 50kmph on a flat, faster downhill, at that speed you...
  12. Hero999

    The voltage varies under load. How can I use a Voltage comparator?

    It's prett easy, all you need to do is connect the output from the dynamo to the battery via a bridge rectifier and connect the load across the battery. The only other thing you might want to consider is adding a zener diode across the the battery to limit the maximum battery voltage to a safe...
  13. Hero999

    final year project: a blind stick that uses different sensors, help needed

    It's not possible because the amount of energy you'll generate by simply banging the stick on the ground won't be enough to power an ultrasonic transmitter. You need a real power supply such as a battery, hand cranked generator or a solar panel.
  14. Hero999

    final year project: a blind stick that uses different sensors, help needed

    Please post a link to the sensor you've found which requires a 5V supply. I don't see why requiring a power supply should be a problem for you: if the transducer were passive (doesn't require a power supply when receiving, which is normally the case) you'll still need a power supply for the...
  15. Hero999

    Where to buy SIEMENS BD287 PNP

    Not that I'm aware of, your best bet is to remove two of any terminals from the circuit and test them with an LED, switch, resistor and battery to check they turn on when triggered.
  16. Hero999

    Where to buy SIEMENS BD287 PNP

    No it's a PNP transistor so will look like two diodes with a common cathode at the base, an NPN  transistor is the other way round. The transistor still might not be working properly, this test isn't perfect although it's now more likely the transistor does work and some other part has failed.
  17. Hero999

    Where to buy SIEMENS BD287 PNP

    If it's broken, it probably doesn't have to be replaced with the same transistor, once with a similar gain and equal or greater, GBWP, voltage and current ratings will do. Do you know the test voltage of the meter? Lots of DVMs have very low test voltages so the can measure resistors whilst...
  18. Hero999

    Camera Capacitor Circuit

    It's not critical, most transistors should work, try the BC338 or BC548.
  19. Hero999

    Camera Capacitor Circuit

    Could you please post the schematic or at least the part number of the transistor.
  20. Hero999

    Happy new year

    A happy new year to you. I notice your last post here was back in April 2006. Welcome back to the forum.
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