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  1. Hero999

    Simple Timer Circuit - help please

    You need a permanent 12V power source for the relay. Your description is a bit vague. A microcontroller should be able to do this.
  2. Hero999

    Transmitting data from multiple sensors using serial interface

    Use a microcontroller with Manchester coding.
  3. Hero999

    12V, 5V, 3A dual power supply based on the LM2596

    It should work. Be careful with the PCB layout which is important for stability and efficiency. The data sheet contains an example PCB so stick to it.
  4. Hero999

    Some transformer advice/help required

    It should be easy to add a timer to delay the pulse.
  5. Hero999

    diodes with breakdown current instead of voltage breakdown

    JFETs are symmetrical - the source and drain connections are interchangeable. http://en.wikipedia.org/wiki/JFET I was talking about a constant current diode which is just a JFET with the gate connected to the source, often via a resistor...
  6. Hero999

    excess supply current from linear voltage regulator

    No it won't  and can't violate Ohm's law. The only exception is if it had a minimum load current which means you need a load connected, in order to regulate properly, otherwise the output voltage would be higher than specified or be unstable but 350mA should be enough to satisfy that.
  7. Hero999

    excess supply current from linear voltage regulator

    No, look up Ohm's law. Hint: the voltage output is constant, the current is not & depends on the load.
  8. Hero999

    diodes with breakdown current instead of voltage breakdown

    It doesn't work like that because as you say, the current needs to flow. You can get constant current diodes which pass a fixed current, regardless of the voltage - it's just a J-FET with the gate connected to the source.
  9. Hero999

    Some transformer advice/help required

    No idea, I'm not a mechanic.
  10. Hero999

    Some transformer advice/help required

    That should work. You may need to connect a small capacitor (say 100nF) from the feedback to 0V for stability.
  11. Hero999

    Some transformer advice/help required

    If you, have ago, post it and I'll check it.
  12. Hero999

    Some transformer advice/help required

    You could be able to connect two capacitors to the output of a single supply, each via a diode so each will discharge separately but you need to make sure the power supply is powerful enough to drive two coils.
  13. Hero999

    Some transformer advice/help required

    Can't you charge each capacitor via a separate diode? Please post a schematic.
  14. Hero999

    Some transformer advice/help required

    Each has its own advantages. Bifilar is good because it ensures each winding has exactly the same characteristics but there will be a greater capacitance between each winding. Centre tapped is easier to wind but the winding won't be quite symmetrical. If you need to charge two capacitors...
  15. Hero999

    7912 as negative voltage regulator issue

    You connected it up backwards so that was going to happen. It's a negative regulator, thus its input voltage should be negative but you gave it postive 12V and fried it.
  16. Hero999

    [need help] Temperature alarm

    Comparator, a few resistors and a relay .
  17. Hero999

    SKIMMER CIRCUIT

    I had to Google is because I've never heard of it before. Are you talking about a card skimmer to steal credit card information? No it's illegal, we don't help you with that.
  18. Hero999

    Universal Ac Adapter

    The thread is 6 months old so why should you expect a response? Please stop resurrecting old threads.
  19. Hero999

    DC motor driver

    What's the maximum current output from the PLC output? How about simply changing the fan for a 24V version? It seems silly to have another 12V power supply for the motor. A solid state relay may work but you need one with a fast turn on/off time <0.25ms.
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