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Kevin Weddle

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Everything posted by Kevin Weddle

  1. Since the device has the capability to operate the LCD, a digital computer based setup seems the most reasonable idea. Since the numbers peak over a small range, you might determine the binary sequence in this range.
  2. A digital circuit to store the highest LCD value might be what you want.
  3. The serial port is often used for downloading data to devices. A demutiplexar can convert serial data into parallel data output. A DC to AC converter is probably the simplest solution for a voltage selector.
  4. Generating a very high voltage with a small battery is an interesting idea. In theory, a transformer can produce any voltage, depending on it's turn ratio. They can also be cascaded. Are there any designs that utilize cascaded transformers, and if so, why isn't one transformer used?
  5. What advantages do permanent magnet motors have over electormagnetic motors? In low power applications, a permanent magnet can be used, but for what purpose? They are always reliable by their design. Does it make them power efficient?
  6. IC's which utilize dual polarity supply voltages are intended to ouput positive and negative voltage. The IC supply voltage must be connected to the rest of your circuit power. Since these IC's utilize ground in most cases, additional circuitry would be needed. It's not simple and it is inefficient design.
  7. The designs for a single polarity and dual polarity supply are basically the same. The rectifiers are opposite in polarity and the voltage regulators are different. The electrolytic capacitors must have the right polarity.
  8. The circuit is a basic amplifier. It may not produce the desired result, unless it engineered to the specification of the MP3 player. The gain looks very low. The capacitors are the wrong value and it may need inductors or additional circuitry for linear amplification.
  9. A voltage multiplier developes a DC voltage from the positive or negative cycle. The input is capacitvely coupled and the sinewave has this DC offset. A squarewave cannot be coupled with a capacitor, so the output is this DC offset when not in transition.
  10. A voltage multiplier might be a consideration. A very simple peak detector in series with a resistor and capacitor load on the piezo could supply adequate squarewave voltage. The parallel RC will be designed for the frequency of 100Hz or lower.
  11. It's more of a dc electronics circuit. The leveling frequency changes the properties of circuit interconnection and impedance.
  12. The accurancy of capacitance measurement doesn't seem possible with this circuitry. Digital electronics occupy a large frequency spectrum. If this is a dedicated measurement microcontroller, what is the engineering addition difference.
  13. Another aspect with these oscillators is the series capacitor inductor in parallel with the inductor. Not being a parallel LC means that the resonant frequency is not 1/(2pi x sqrt LC). The capacitive reactance does not equal the inductive reactance as it does in a resonant parallel LC. However, the reactance of the inductors will be equal at any frequency with a center-tapped transformer.
  14. Transformer's can be used in frequency resonant ciruits to allow for feedback. Their even ratio might be beneficial to the equation of oscillation, and there is no power consumption .
  15. Walid, A parallel LC filter circuit has a roll-off of 40db/decade outside the resonant frequency. An oscillator requires high gain, but it's selectivity can be independant of the gain circuit. The final design depends on the characteristics of the circuits and the components used.
  16. The output could be negative 4v depending on the design, or it may be negative 200mV depending on it's assembly with the current design.
  17. The -VGS biasing is similar to a DMOSFET and their input impedance is very high. So mistakenly, a JFET should replace MOSFET's and bipolar transistors in many instances. And aren't biploar transistors prefered in low frequency circuits with low supply voltages, making the use of MOSFET's even less desireable?
  18. Should JFET's be eliminated from circuit designs? If not, are there any examples of circuits with characteristics only obtained by using JFET's?
  19. Deciphering simple logic circuits is easier than designing simple logic circuits. Simple logic circuits are used to interface larger logic circuits. Larger logic circuits have to be designed mathematically and are excessively complicated.
  20. You might consider using a bipolar transistor based receiver input, which is more common. Selectivity and gain can limit the use of simple circuits. But several tuned circuits and amplifier stages can recover weak transmissions. Many of which utilize IC's.
  21. The variable capacitor has to be a higher impedance than the series inductor so that the collector voltage is inverted compared to the base voltage. Unless the feedback capacitor and transistor base add to the phase shift, the amplitude is reduced by at least 75%.
  22. Solid copper wire solders good to component leads. High voltage on PCB's isn't good. Any sort of damage has to be evaulated for reuse.
  23. Then C1 has a low impedance compared to the transistor input impedance? Where is the collector voltage compared to C1 input voltage?
  24. The circuit layout can produce 270 degrees of feedback. Is C1 and the emitter resistor used for any of the phase lag, or is C1 just a coupling capacitor?
  25. Is there any reason for the center-tapped inductor being standard to the Hartley Oscillator? Using two inductors should allow for a better design because this part of the circuit has less tolerance. Or is there a mathematical advantage to using the center-tapped inductor?
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