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  1. Hero999

    transistor help !!

    Some of those transistors are NPN and the others PNP so are not interchangeable. You need to makse sure the transistor can handle the current surge when the motor starts. The base resistor depends on the control voltage i.e. what's connected to the base. To ensure good saturation, the base...
  2. Hero999

    a site that post different components but functionally are almost identical

    I think you mean reverse voltage. The reverse current is typically 5uA@25oC and the maximum rated voltage. The higher voltage parts (>=600V) have a lower junction capacitance, 8pF as opposed to 15pf which makes no difference in most applications. unless you're using it as a varactor in a...
  3. Hero999

    Solar driven car

    Yes you'll burn a starter motor out by running it continuously.
  4. Hero999

    12v 1A automatic charger fault, loud buzzing from transformer.

    The voltage are what you should expect - nothing wrong there.
  5. Hero999

    Measuring low current on high voltages?

    No never remove the fuse from the meter. The meter's insulation is only 1kVDC, if you try to measure 100kV, an arc will jump through the case which will both damage it and you'll get a nasty shock.
  6. Hero999

    Driving a Bar Graph LED, 5-15v

    Here's a similar project giving an example of how to do this: http://www.enide.net/webcms/index.php?page=lm3914-batmon
  7. Hero999

    alarm circuit issue

    Please post a schematic.
  8. Hero999

    Help with using transistor as both N.O & N.C Relays

    The NC function generally needs a permanently live powersupply but there are ways round it. The simplest way is to is to use a depletion mode power MOSFET or a JUGFET driving a BJT being driven by a small pulse transformer. Another trick involves using a small battery to bias a transistor on...
  9. Hero999

    LED IC chip board for flameless candle

    You need to attach the image. Click additional options, then choose, find the file containg the image and click on open.
  10. Hero999

    LM317

    That's probably not such a good idea. It's a fairly low cost part and if you're unlucky enough to find a bad one in an old piece of equipment, you could waste a lot of time fault finding. It's really best practise to use new and known good parts for a prototype.
  11. Hero999

    Any Clue what this is?

    You're right, it's a pair of diodes. It's actually quite common to get high power diodes in this kind of configuration. They're commonly used to connect two batteries together or as as a full wave rectifier with a centre tapped transformer in a switched mode power supply. Have you tried typing...
  12. Hero999

    Any Clue what this is?

    The clue lies in the symbol at the bottom of the package.
  13. Hero999

    1 Bit Full Subtractor. HELP! ^_^

    http://www.electronics-tutorials.ws/logic/logic_6.html http://www.ustudy.in/node/3036
  14. Hero999

    LM317

    Why not buy one? The LM317 is a cheap commonly available part. If you see one in an old piece of electronics then use it, but it may not be as reliable as a new one. You should always opt for new parts whenever possible.
  15. Hero999

    Help with power for sous vide circulation pump

    The current is not the proble, it's the voltage. You just need a 12VDC power supply capable of supplying more than 380mA, 500mA or 1A would do. I wouldn't recommend going over a couple of amps unless you add a fuse but that's only in case it develops a fault. You could use a 12V 100A PSU if you...
  16. Hero999

    555 calculation in astable mode

    The LED should be wired from pin 3 to 0V in order to have a duty cycle of greater than 50%.
  17. Hero999

    Best means for a dual vref?

    To answer the origional question. It's definitely better to use a potential divider and a 5V reference. If more current is required, a non-inverting buffer could be used to reduce he output impedance.
  18. Hero999

    Best means for a dual vref?

    It's impossible to say without any additional information such as a schematic or detailed description of the circuit.
  19. Hero999

    How to change 5DCV into +/- 5DCV

    How muchpower do you require? It's possible with the ICL7660 but it's restricted to low currents. http://datasheetoo.com/power-supply/generating-negative-supply-using-the-icl7660-circuit-schematic-and-datasheet.html
  20. Hero999

    Power Line Communication

    http://uk.farnell.com/cypress-semiconductor/cy3277/programmable-lv-powerline-communication/dp/1828765?CMP=KNC-GUK-FUK-GEN-KWL-G30-CYPRESS_SEMICONDUCTOR
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