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  1. Hero999

    need to build soil moisturizer level detector...

    I've just Googled for 12V pumps and they seem pretty easy to get hold of and start at reasonably low prices too. http://www.towsure.com/product/832-Submersible_Pump_(12_Volt) It's certainly cheaper to buy a 12V pump than it would be to make/buy and inverter and a mains powered pump.
  2. Hero999

    JFET Mic Pre Advise Please

    If the source is clipped, then it doesn't matter how good your amplifier is, it won't sound any better.
  3. Hero999

    JFET Mic Pre Advise Please

    More stages of amplification = more gain = more negative feedback = lower distortion. A correctly designed op-amp circuit will have much less distortion than any circuit lashed together from transistors. If the circuit is properly designed the you won't have to worry about distortion, graceful...
  4. Hero999

    need to build soil moisturizer level detector...

    I agree, especially with your point about the AC pump, it sounds like a silly idea. You could use an automotive windscreen washer pump which is a pretty standard part you can probably pcik up for next to nothing from a scrapyard.
  5. Hero999

    JFET Mic Pre Advise Please

    I don't see anything wrong with the schematic, it's not fuzzy, audioguru should think about getting his eyes tested. ;) JPEG is only bad if it's set to low quality or the picture has been edited loads of times. I recommend PNG or GIF schematics but I certainly wouldn't chastise anyone for using...
  6. Hero999

    Testing a 3 phase transformer

    It does seem weird how the neutrals are connected together; was it easy to disconnect them? I would have guessed it was an autotransformer by the fact that the primary and secondary neutral are the same. I agree that the primary resistance will be, below 1Ω, if it's a large transformer. If you...
  7. Hero999

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

    If you're using a microcontroller, then why aren't you using the digital output? Look at the section of the datasheet referring to the PW output, if you want to do PWM it's your best bet but you might need to tweak it to give the output you desire.
  8. Hero999

    Simple FM transmitter question/s + help

    It sounds like it could be a loose connection to me. Another explanation is that moving your hands near subtly alters the properties of parts the circuit (i.e. capacitance); this can be solved by putting it in a screened enclosure. You might also have a problem with the air coils being...
  9. Hero999

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

    It should be fairly simple. What do you have in mind for the vibrator, a motor with a weight attached to the end fo the shaft? It should be fairly easy to use PWM to vary the speed.
  10. Hero999

    need a thermal fan controller for noisy power supply fan

    The simplest solution of course is to buy a fan with a lower noise rating. Here's a circuit for a light/dark detector, if the LDR is replaced with a thermistor, it can be used as a thermostat. http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=17
  11. Hero999

    Capacitors

    What value is the above poster's flux capacitor?
  12. Hero999

    VOLTAGE DOUBLER

    Why not simulate it? That's what I've done, being to sit down and lazy to figure it out. ;D The voltage at each point you marked will have ripple super imposed on it so you'll need to add a diode and capacitor, if you want to use them. The voltages are all negative: you need to reverse the...
  13. Hero999

    how to use the transmitter and reciver modules

    The maximum bit rate is only 3kbps, if you're lucky, which is far too slow for audio.
  14. Hero999

    need to build soil moisturizer level detector...

    http://www.faludi.com/2006/11/02/moisture-sensor-circuit/
  15. Hero999

    Reset on 2-digit LED counter

    Have you tried calling or writing to them? Emails are too easy to ignore or get blocked by a spam filtering system. We won't be able to help you give us the schematic or at least a clear photograph of the PCB so we know what counter IC is used. Otherwise it's like asking a mechanic what's...
  16. Hero999

    1.5v to 5v

    Yes, the capacity is inversely proportional to the current drawn, the higher the current the lower the capacity. http://data.energizer.com/PDFs/E95.pdf The oscillator part of the circuit consists of two inverting amplifiers formed by Q1 and Q2 with positive feedback. The inductor and capacitor...
  17. Hero999

    1.5v to 5v

    A 1.5V D cell can provide a lot more than an Amp which is good because it isn't possible to convert 1.5V to 5V 0.5A without drawing more than 1A. I can't remember what the frequency was when I simulated it. I remember adjusting the component values because it was very low with the original...
  18. Hero999

    Reset on 2-digit LED counter

    Why not ask the supplier? http://www.surplusshed.com/contact.html They're the one's who designed it.
  19. Hero999

    how many 10v leds for 230AC and a few other questions.

    Yes, if you needed 10k and you used 1k then you could solder 10k or 9k1 in series but as 1k is a reasonable value, you don't need to.
  20. Hero999

    Solar powered Light

    Your lights must either be good quality or perhaps the underpaid Chinese engineer didn't think of using the solar panel as a light sensor? I have a couple of solar garden lights. They both use the solar panel as a sensor like my circuit. I opened one of them up to see the shoddy soldering. I...
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