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  1. L

    Circuit maker program?

    While I draw most schematics using the TurboCAD drafting program, don't overlook the very capable drawing program that is a part of OpenOffice.org 3. You would have to spend several hours drawing the basic symbols you want to use (resistor, capacitor, transistor, mosfet, ground, switch, etc.)...
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    A couple general questions about DCV to ACV

    Without going into the integral calculus behind root mean squared computations, realize that RMS voltage is the equivalent steady DC voltage that would produce the same heat dissipation in a resistor as the waveform for which the RMS value is calculated. While any periodic or random voltage...
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    100 Day Countdown Timer.

    If you can find a small cheap watch that you can set the alarm for 100 days in the future, then you are all set. Otherwise the crystal oscillator in a watch is usually at a frequency of 32,768 Hz. So a counter for 100 days would need to count 32768*60*60*24*100=283,115,520,000. Now the...
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    gear indicator wiring HELP

    What you need is a 3-input/6-output decoder where the six outputs will drive six relays or transistor switches that will ground the six inputs to the display device. The 3 inputs will interface to the 3 transmission outputs and be inverted as necessary. The decoder can be implemented with dual...
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    Combination Network

    It appears that the circuit consists of an equivalent model of a transistor in a CE configuration with a 3.3K load resistor and the collector tied directly to the virtual ground, '-' input, of the op amp so that both ends of the load resistor are at signal ground. All of the output signal...
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    Hysteresis

    It might be easier to visualize if you replace R1 & R2 with the Thevenin equivalent circuit. Then the Thevenin voltage is the nominal switching point. When you add in R3, the switching point will shift depending on whether the output driving R3 is high or low. The difference between the...
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    Combination Network

    The question does not make sense. The presence of the op amp changes everything.
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    Hitachi C50-24S

    This link may give you some ideas: http://forums.entechtaiwan.com/index.php?topic=893.0
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    Help with calculating total resistance

    It looks like your formulas are OK but you need to do the calculations with complex algebra since that method allows for combining resistance and reactance into a single impedance. Note first that reactance is represented by an imaginary number (Zl=jωL, Zc=1/jωC) where j=sqrt(-1). If you are...
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    Basic Project Selection

    When I was in high school electronics I built a combination of your first and last selection: a tone generator controlled by a 10-turn potentiometer with a built-in LED display frequency counter on a timebase derived from a crystal oscillator, all in a handheld box. Back then all we had were...
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    Want to buy a soldering iron

    This is the soldering iron I've been using for the last 5 years. Before that I had used an Ungar with a Dremel TRIAC Controller. I think it is important to be able to adjust the temperature of the iron. http://circuitspecialists.com/prod.itml/icOid/7307
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    Need information about pulse shaping amplifier

    If you are talking about generating a ramp at a given frequency, then you will have a capacitor in the feedback loop of an op amp, forming an integrator. Capacitance is defined as the ratio of charge to voltage or the change in charge for a change in voltage. C=Q/V=dQ/dV=IdT/dV where I is...
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    Transistor selecting

    This would be my solution. It's similar.
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    Need IC to output first input state received, then stay that way

    An SR flip flop is the simplest approach. But the output state can be indeterminate if the SET and RESET inputs are asserted at the same time. If that might be a problem, then a JK flip flop with the clock input driven by your input signal and the JK inputs wired to make the output go HIGH may...
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    Rock Band/Guitar hero drum pedal issue

    The pulse coming out of pin 4 will have a duration on the order of 0.1 second. So the microswitch in the pedal will need to stay closed for at least 0.1 second. However, a piezoelectric sensor will have a resonant frequency near 3 kHz so the output pulse will likely have a duration much...
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    Simple 6 LED Random

    Oscillators are an analog approach. Try Google "Pseudorandom number generator". This is a digital approach most often implemented with shift registers and gated feedback to the input of the shift register. The simplest circuit overall would use a single microcontroller driving the LEDs...
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    ground node

    So the ground node has no magical affinity that sucks charge from a circuit (or a capacitor) to prevent current flow. I would think all that is required to make a node a ground node is to draw that little ground symbol on the node, although it would not be very useful to select a node that was...
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    Calculating the half power frequency

    Here are my calculations doing it the long way.
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    ground node

    How is a ground node different than any other node? If you charge a capacitor then connect one lead to the ground node and leave the other lead unconnected, does half the capacitor lose its charge? Or is the ground node just the reference point from which other voltages are measured? What...
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    Calculating the half power frequency

    The gain of a network is Vo/Vi. The gain of this network is a function of frequency. Since this is a low-pass filter, the highest gain will be found at f=0 so the gain at the cutoff frequency will be half the power of the gain at zero frequency. An alternative method is to realize that the...
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