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Hero999

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Everything posted by Hero999

  1. 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 transistor to get enough amplification. A simpler approach would be a comparator or logic gates.
  2. 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 basically a pre-built control module which can be user programmed.
  3. http://www.gillsensors.co.uk/content/level.htm
  4. 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. Thats RMS, the average is simply the duty multiplied by the voltage. Sorry, I don't understand what you're saying.
  6. 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 is with an oscilloscope.
  7. 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 measured the motor current? You've grossly underrated the components so why are you surprised they're overheating? You should replace the motor with one rated to at least 6V and a suitably rated transistor such as a small MOSFET.
  8. 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. There are other better places to buy components from than Radio Shack. Type bistable multivibrator into a search engine.
  10. 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. 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. A light meter can be used to measure intensity. A spectrum analyser can measure the power at different wavelengths.
  13. You can buy small inverters pretty cheaply. http://www.google.co.uk/products/catalog?q=inverter&hl=en&prmd=imvnsr&psj=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1216&bih=559&um=1&ie=UTF-8&tbm=shop&cid=13678764363958360615&sa=X&ei=aO9mT69x4bHQBcrYqMAI&ved=0CKMBEPMCMAI
  14. 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 through the water, the probes will corrode over time due to electrolysis. This can be solved by using AC which doesn't cause electrolysis or corrosion.
  15. 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 for connecting an external speaker, microphone or trigger switch. It may be possible to dismantle the unit and interface it with your own but you'll need to know what you're doing. I don't see why you'd need to interface with it. The mirror will play back the pre-recorded phrase when it detects something (i.e. a person) is in front of it. What else do you want?
  16. 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. Brightness is only half the story: colour rendering index and beam angle are also important.
  18. 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. 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. Sorry we only help via the forum not email. What do you need help with?
  21. It means an input with CMOS logic levels. This is because modern microcontrollers use CMOS technology. Wikipedia has lots of information: http://en.wikipedia.org/wiki/CMOS http://en.wikipedia.org/wiki/Logic_family#The_CMOS.E2.80.93TTL_logic_level_problem http://en.wikipedia.org/wiki/Logic_level
  22. Then find one which closest meets your needs and adapt it. That's not a full specification. How much are you willing to pay for someone to design it for you?
  23. You may get more help if you provide a proper specification. You also need to learn how to use Google. http://www.google.co.uk/search?hl=en&client=opera&hs=NYc&rls=en&channel=suggest&q=SMPS%20schematic&gs_sm=3&gs_upl=14867l16551l0l16708l10l5l0l5l5l0l63l289l5l10l0&bav=on.2,or.r_gc.r_pw.,cf.osb&biw=1920&bih=927&um=1&ie=UTF-8&sa=N&tab=iw&ei=kdRIT7raIs-p0AWduemYDg
  24. You could build your own dual 5V isolated PSU using a transformer with twin 9V secondaries and have a bridge rectifier, filtering capacitors and LM7805 on each secondary.
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