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  1. Hero999

    Triggering transistor via Iphone's audio output jack

    Your LED circuit already has a 5V supply and you want it to turn off, not on when the audio is present, so the transformer idea won't work. My first question is why are you doing this? Secondly, how long does the LED need to remain off for when audio is present? You need more than one...
  2. Hero999

    hey boyz and girls can anyone tell me if i'm smok'n something good?

    Your drawing says, you need 5kg to 10kg of force over a 50mm to 70mm length but you didn't say how fast it has to move? It's quite a lot of force for a solenoid. Another solution could be pneumatics. The simplest control solution would be a PLC (Programmable, Logic, Controller), which is...
  3. Hero999

    capacitive liquid level sensor

    http://www.gillsensors.co.uk/content/level.htm
  4. Hero999

    pwm to control a dc motor

    So what you're saying is when the motor's supply voltage is increased beyond its maximum rating, the current also exceeds its maximum rating? Why are you surprised by this? It's what you should expect to happen. Read up on Ohm's law.
  5. Hero999

    pwm to control a dc motor

    Thats RMS, the average is simply the duty multiplied by the voltage. Sorry, I don't understand what you're saying.
  6. Hero999

    pwm to control a dc motor

    Do you know how your meter measures voltages with an AC component on the DC range? Does it take the average value, RMS or does it behave unpredictably? You need to look at the meter's manual or ask the manufacturer. Failing that, the only way to accurately measure the voltage of such a signal...
  7. Hero999

    pwm to control a dc motor

    Yes, you do get more than 0.3A, when the motor starts it has to overcome the inertia to get the shaft spinning so the load will be much higher, 5A or more wouldn't be surprising. If you're running the motor at 7V when it's only rated to 3V, the current will be even higher. Have you actually...
  8. Hero999

    pwm to control a dc motor

    The motor acts as a dynamo when the power is disconnected from it while the shaft is spinning so it will generate a voltage.
  9. Hero999

    Laser alarm system not working correctly..

    There are other better places to buy components from than Radio Shack. Type bistable multivibrator into a search engine.
  10. Hero999

    pwm to control a dc motor

    The transistor is getting hot because you're not driving it into saturation. The data sheet specifies a gain of 40 when VCE is 10V. Try increasing the base current to 30mA.
  11. Hero999

    Laser alarm system not working correctly..

    Yes, you could use an SCR (thyristor) which will turn on and remain on until the anode current is interrupted or you could use two transistors configured as a bistable multivibrator.
  12. Hero999

    Brightest White LED

    A light meter can be used to measure intensity. A spectrum analyser can measure the power at different wavelengths.
  13. Hero999

    12 V DC - 220 V AC (DC Flourecent lamp)

    You can buy small inverters pretty cheaply...
  14. Hero999

    Quick question.

    Are you talking about R2 and R3? They pull the bases of the transistors down to 0V when there's no signal. Without R3 and R2, it's possible some noise could turn on Q1 or the leakage through Q1 could turn on Q2 and generate a false alarm. This isn't the best way to do it. Because DC is passed...
  15. Hero999

    Talking mirror

    They're not designed to be interfaced with one another or a different circuit, although I'm not going to say it's impossible. The proximity sound recording module I linked to has a built-in microphone, speaker and proximity sensor and the battery holder is pre-wired. There are no plugs, sockets...
  16. Hero999

    Talking mirror

    My local electronics supplier sells recordable sound modules. Here's one with a proximity sensor which may be suited to your application: http://www.rapidonline.com/Education/Sound-recording-module-with-proximity-detector-82133 http://www.rapidonline.com/pdf/13-0671.pdf
  17. Hero999

    Brightest White LED

    Brightness is only half the story: colour rendering index and beam angle are also important.
  18. Hero999

    Electronic Music Box Project

    The trouble is, to get an authentic sounding bell, you need to adjust the decay time along with the frequency so a low pitched bell rings for longer than a high pitched bell.
  19. Hero999

    Why caps in paralell?

    Not that it matters, 22pf or 27pf could be used instead. Another reason for using many capacitors in parallel is it gives lower impedance to higher frequencies if they're spread across the PCB traces.
  20. Hero999

    job offer - small stepper motor driver w/RTC

    How much are you offering?
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