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  1. Arouse1973

    Non-changing current with C-EMF

    Ok XRZ lets have a go. You need gives us some info. We need to know the size and length of the wire and current in the wire. We need to know what the EMF source is. Inductance, frequency, and voltage. Make it up if you have to but be reasonable. If not I can assume a few things. I cant do it...
  2. Arouse1973

    Non-changing current with C-EMF

    It works in the same principle as the example I gave, you will always need a good headroom of voltage so that when the resistance changes the same amount of current can still be drawn by the load. Modern constant current sources use different kinds of feedback to control this but the principle...
  3. Arouse1973

    Non-changing current with C-EMF

    This is what I think A constant current source is just a high voltage source with very high resistance so no matter what resistance you attach to it is so small in comparison that the current appears to stay the same. As far as the source is concerned the varying voltage caused by the induced...
  4. Arouse1973

    Constant current regulation with boost converter, PWM and 555 timer.

    Isn't a current transformer an A.C device? Adam
  5. Arouse1973

    High Amperage Power MOSFETs

    Also the data sheet will normally give the conditions for this max current. It might say with a VGS of 10 Volts and then there should be an on state resistance also with a VGS of 10 Volts and possibly a pulsed current of some value. This would indicate as Kris has said the transistor is fully...
  6. Arouse1973

    Non-changing current with C-EMF

    Can you explain why you are doing this, what's the idea behind the project. We have been doing this sort of thing with data packets on long cables for years with constant current, it's called a 4-20 current loop. As Steve said use a constant current generator if you want to maintain a current in...
  7. Arouse1973

    Adjustable Power Supply

    Here is a simple low voltage drop adjustable regulator based on the LT1085. It would be a good idea to use a heat sink also for the device to prevent over heating. P1 is a 1W standard linear POT and is used to adjust your voltage. This design only has variable voltage and not current so be...
  8. Arouse1973

    Adjustable Power Supply

    Resistors would probably generate too much heat and waste energy depending on how much current you are supplying. They also won't keep the voltage that stable if you are drawing different amounts of current from one of the resistors. You need something with feedback to regulate the voltage...
  9. Arouse1973

    Dimmable mains LEDs

    Just tell her it's so you can see how beautiful she is :) Adam
  10. Arouse1973

    Dimmable mains LEDs

    What I meant was add a bulb in parallel to the dimmer so it's driving an incandescent bulb. Not to replace any of the LEDs. You may be able to use a high wattage resistor in place of the bulb also. Once we know if this works then we can looks at that. Adam
  11. Arouse1973

    Dimmable mains LEDs

    Yes it might work. Adam
  12. Arouse1973

    Controlling a motor.

    Isn't that strange, I work with one of the guys that designed part of the SEGWAY when he worked for BAE Systems. I have actually seen footage of him driving the first prototypes around an office block. He showed me the large Gyro housing used for controlling the balancing, it's very impressive I...
  13. Arouse1973

    Dimmable mains LEDs

    That's an interesting question, I am guessing that it's load dependant as I know most dimmers have a minimum load current requirement. this is to ensure the TRIAC is triggered correctly and the holding current is maintained. As the LED light is dimmed this draws even less current and would make...
  14. Arouse1973

    12V - 350V 200mA converter for motorcycle CDI

    Yes I agree Steve, the benefits of a gapped core far out way the downsides in most applications. Adam
  15. Arouse1973

    Graphite painted cards and varying resistance

    I think it all depends on where you make your connections. Mark two points on the card and measure the resistance, if you then use these same points for your connection then this will be the value of resistance across your connections. These points will then behave as a resistor and you can...
  16. Arouse1973

    12V - 350V 200mA converter for motorcycle CDI

    Yes correct, a gapped core adds reluctance to the core which lowers magnetic flux which in turn reduces saturation currents and improves core buzz from magnetostriction. And this also stabilizes the inductor value versus current. Adam
  17. Arouse1973

    Adjustable Power Supply

    If the load stays the same adjusting the voltage will naturally change the current. You would only need to adjust the current if you were operating the load in constant current mode or current limited mode of some kind. The load will only take what current it needs to satisfy V=I*R (derived from...
  18. Arouse1973

    How do LDRs work?

    Hi Jamie This is not a dumb question. The LDR is actually made of a semiconductor material called Cadmium Sulphide and as light (photons) hit this material they knock out an electron from the valiant band of the atom and this electron is now ready to became part of the current through the...
  19. Arouse1973

    How to decrease fluctuations

    That's fine, it's better we see what going on. In the meantime maybe you can explain a bit more about the project and how it's designed to work and what it's for. Adam
  20. Arouse1973

    How to decrease fluctuations

    Can you tell us the frequency and amplitude of the oscillations? Better still post an oscilloscope capture here. A circuit diagram would also be good. Adam
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