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  1. C

    50Hz when you touch Oscilloscope probe

    Indulis - explain please what happens when you do this with a battery operated scope. I'm curious to know.
  2. C

    50Hz when you touch Oscilloscope probe

    Yes, as I said, capacitative coupling. I'm pretty sure there is almost no electromagnetic phenomenon involved in 50Hz mains pickup. The body's capacitance to ambient electric fields is a few picofarards. When you touch the scope probe, you become a 10pF capacitor in a series circuit - a 50Hz...
  3. C

    50Hz when you touch Oscilloscope probe

    I understand it's your body's capacitance with ambient that couples you to the mains. A few picofarads. That's enough to deliver a volt or so to a high impedance at 50Hz. It is electromagnetic in nature, of course, but I suggest that "picking up mains radiation" is misleading.
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    Networks

    In the first picture I've drawn a classical representaion of the voltages across the elements in a simple battery/load circuit. I am careful to observe that the voltage arrows always point to the higher potential end of the component. When this is so, the voltage is always marked against the...
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    efficient 12v to 5v regulator chip.

    Or, you could get a tiny switcher from this site's advertisers here: http://www.dimensionengineering.com/DE-SW0XX.htm 80% efficient, 1A output, and a tiny drop in replacement for the 7805! I haven't tried any, but they sure look good to me. If they really are over 80% efficient, these units...
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    Transistor combinations questions

    Not much actually - when the switch is pressed, the pair of inverters will change state and settled into a condition in which the switch is no longer fighting the collector of the first transistor. If the first transistor is switched fully on, though, it is effectively a short circuit from its...
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    Transistor combinations questions

    Very true, well spotted. I am tempted to call this a "hard reset feature" of the circuit.
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    Beginner Question about Ohm's Law Thanks!

    Zeppelin pointed out that the battery in my little circuit is drawn upside down. He's right - the positive side should be at the top, so that the upwards Vs arrow is in the right direction. Kirchoff must be turning in his grave. My apologies. To hide my shameful error, I've edited the post wth...
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    Beginner Question about Ohm's Law Thanks!

    The picture is a simple battery connected across two resistors in series, as you describe. The first thing to understand is that the current is the same everywhere in the loop. There's nowhere for current to leave the circuit, so the current is the same at every point around it. I've labelled...
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    Transistor combinations questions

    Just a couple of small diagrams of how inverters can be used to make a bistable multivibrator. The resistors 'R' are present to avoid connecting a power rail directly to the output of a gate, which is bad. The switches are pressed momentarily to force an input to a specific level (high or low...
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    Transistor combinations questions

    Astable means NO stable condition. That is, an astable multivibrator will never settle into a fixed state - it will always switch from one state to another and back, all on its own, without any external input. Lamp flashers are astable, needing no external input to switch from off to on to off...
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    A simple transistor switch for an LED light.

    That was indeed an awsome reply!
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    Beginner's Question 2

    It's one of the most misunderstood things in electronics - voltage. The problem is that people think 9V is 9V and that's that, but really it means 9V higher than somewhere else. On a 9V battery, the '+' terminal is 9V higher than the '-' terminal. In other words, the battery is generating a...
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    HOW REFLECTIONS TAKE PLACE IN TRANSMISSION LINES

    For a complete and utterly mind boggling explanation of this, see "Electromagnetics" by John D. Kraus. In the meantime though, here's a simplistic "Transmission Lines for Dummies" view of what's happening, and I guess a few radio engineers out there will be shaking their heads in dismay after...
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    free energy motor

    Indulis - great strides have been made, but the greatest ones are always those that disprove previous assertions of law, or at least of commonly accepted limits. The copper is proably the same, but they twisted it. I mean, somebody had to think "hey, I wonder what would happen to latent...
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    6V 5A PSU problem.

    The biggest source of ripple is from an inadequate reservoir capacitor between the bridge recifier and the regulator. Make that bigger, and you reduce the ripple at the regulator's input, and the regulator's ripple rejection isn't stretched so far. Assuming you are drawing 1A from the supply's...
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    free energy motor

    At university in 1988 I was taught some facts and figures about networking and electronic communications. Some of it was very compelling matthematical proofs of what can and can't be sent down a wire link, such as telephone wire. At that time it was deemed impossible to carry anything over...
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    free energy motor

    The concept is called "over-unity systems". Just Google for over-unity, and you'll find an overwhelming number of web sites that claim to know all about them. And probably don't. Maybe somebody succeeded with this, but nobody's ever managed to demonstrate it to the public at large. It's a myth...
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    HELP NEEDED

    I'm afraid you are going nowhere with this. Any design needs numbers. Get numbers. Get details. Without them your project is only a little less vague than "make a kind of thing that sometimes does some stuff, perhaps, and some other stuff." It is just not feasible to start off with "any range"...
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    HELP NEEDED

    What range of frequencies, approximately are you measuring? And what amplitude (voltage) range is the input likely to be?
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