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  1. K

    ATX power supply

    Don't ground out the PS on unless you are sure. I think there is something in your circuit that is causing your fuse and capacitor to blow. Try this. Unsolder components. Just take them out, except for the rectifiers. You might even cut a trace to isolate the problem. This is going to be major...
  2. K

    square wave to sine wave converter

    How do you get the output of an oscillator to produce a sinewave? I believe the ouput of an oscillator is more like a triangle. What we need is a sinewave generator instead of turning a square wave into a sinewave. I don't think it is possibe but I will continue to investigate...
  3. K

    timing circuit to run N-times

    It sounds you like you want a variable oneshot. The one shot will deliver a pulse for a duration with an input pulse. You pulse the input for a short duration and the one shot produces an extended pulse. I'll have to check how you vary the pulse of a one shot.
  4. K

    triggering pulses to mosfet

    It might be of some use, but you can use the output of a gate and set an inductor to ground. This means that with the occurance of an input, like a switch from low to high, you get a pulse that goes low to high back to low. A simple one shot that does not require a pulse on the input. Just a...
  5. K

    big ear, fm transmitter.

    And yet the radio eminates along a ground path. The radiation pattern of an airplane transmitter must be very large as you are so high up. As they transmit, the radiation pattern is still along the ground.
  6. K

    Led Display Digital voltmeter problem with 200mv scale

    It sounds pretty stable to me. When you consider you are measuring fractions of a millivolt, I would suspect noise and missmeasurement. I'm just guessing, but the thing is probably accurate in the few millivolts range simply because the best meters only display the millivolt range. A millivolt...
  7. K

    environmental test chambers

    I use a hot and cold chamber at work. It is very circumspect as to what is being accomplished. I have seen test setups on interviews that use pure digital logic and wonder how effective the results will be. I have come to the conclusion that the temperature affects the metal all over the circuit...
  8. K

    big ear, fm transmitter.

    I have often wondered about antennas and I will try to explain what I think happens. Did you ever wonder how a cell phone antenna works when there is no ground. Or how an airplane antenna works. The reason I have wondered is becuase they show a ground based antenna in the drawings. The signal is...
  9. K

    Beginers OPAMP question

    Audioguru, I knew you would disagree with me on this. Haven't we had this discussion elsewhere? The collector resistor I am talking about is the effect the feedback resistor has on the internal stages of the opamp. Now, If you look at the input stage, the input resistor beomes an emitter...
  10. K

    The backwards transistor

    Doesn't a MOSFET also have the same problem when you apply a signal to the source. The input impedance is too low. It is only 1/gm.
  11. K

    The backwards transistor

    I have an idea to develop a backwards transistor. I had this idea from the limitations I was getting. I wanted to operate the collector of a common base as an emitter. The reason is for the high impedance aspect of the collector as seen by the rest of the circuit. If I used an emitter, the...
  12. K

    Barrier potential discrepancy

    I thought I would give this new section a try. What about the diodes barrier potential. We all know that it measured with a meter and the polarity is that of the battery. I have read, though, that since the free electrons move from the N type to the P type, a negative potential appears in the P...
  13. K

    Beginers OPAMP question

    I have luck with setting the output bias current. You do that with a resistor to the negative supply. This will give you the offset. Without the bias current, you are dealing with a dead opamp. But of course you will still get the output voltage by virtue of the total current going around the...
  14. K

    square wave to sine wave converter

    Brilliant observation. You can in fact get something of a sinewave output as long as the time constant is short. You want to quickly charge the capacitor where it will rest at the DC. Then you can append a filter network. This might involve another amplifier stage.
  15. K

    H Bridge Driver

    Since you have taken out the 1Kohm resistors on the top half of the circuit, you are ready to apply the highs and the lows. You will have 100 volts across the load when you are done. So watch out. The best way to do it is to use two inverters on one of the inputs. It looks like the top inverter...
  16. K

    H Bridge Driver

    I don't think you need the 1Kohm resistors on the top half of the circuit. I don't know what you mean about the 10mA. The circuit is designed to give you zero volts across the load. The 1Kohm resistors on the top half will drop the voltage across the phototransistor to zero volts. They should be...
  17. K

    Beginers OPAMP question

    Thanks Yevgeni. I am really proud to help out those in need of electronics advice. I have 10 years experience and feel that I am still learning. Thank you again.
  18. K

    no phase difference

    Did you mean some sort of feedback. Do you want the phase to be equal so that you can directly change the input signal. Often a large feedback loop can be acceptable. If you want to use a large feedback loop you have to use a servo circuit. Direct feedback will produce a net result. And yes you...
  19. K

    Help: Circuit Design 4in NOR Gate

    There is a way to simulate the input of a gate so that it matches the output. You could load the output with another gate just to match it right. Otherwise, you should simulate the situation using the correct current draw which for TTL the source is less than the sink. If you use a common base...
  20. K

    rounding off sq. roots

    The length of the arc is a neverending fraction because as you try to measure it's length using a series of straight lines, you always have a bow no matter how many straight segments you use. The sheer number of straight segments that you must use to get the length is neverending. The more...
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