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  1. K

    Pulse transistion time

    Thank you audioguru. Although Schmitt triggered digital devices seem more reliable, isn't it a form of positive feedback that prevents noise from switching the device?
  2. K

    varactor diodes

    Does a varactor diode release any stored energy when the voltge is removed, like a capacitor or inductor does?
  3. K

    Pulse transistion time

    A circuit based on a 1KHz clock has a longer pulse transistion time than a 10Khz clock. But couldn't it have the same transistion time? Is there a circuit to reduce pulse transistion time and make a low frequency digital circuit perform better?
  4. K

    LC filters

    For example, a passband amplifer can have as little as 20db/decade roll-off. A cascaded passband amplifier can have a much higher roll-off. I normally see many filters in a circuit, is it to achieve an exact amount of filtering? I have 120Hz 10mVpp ripple coming from my 7805 voltage regulator...
  5. K

    LC filters

    LC filters have good attenuation at low frequencies and are less suitable at higher frequencies. 40db/decade is the attenution. Is -3db the nominal attenuation for unwanted frequencies? Should the final attenuation be more or less than -3db in order to be finished with filtering.
  6. K

    Parallel LC

    Can a parallel LC, buffered from an oscillator, be used to determine the frequency of an oscillator? A parallel LC has only one resonant frequency.
  7. K

    MOSFET VGS

    A typical MOSFET can have a VGS of 3 volts. A bipolar transistor has a base emitter bias of about .7 volts. The emitter voltage is often low with both transistors, so a 5 volt voltage source would have less than 2 volts to bias a MOSFET.
  8. K

    MOSFET VGS

    How can MOSFET's be used in low voltage circuits when their VGS is high?
  9. K

    Light bulbs

    There are several ways to calculate light bulbs. Producing a 60W light bulb at 120Vac is one way. Measuring the resistance of the filament and the applied voltage is another way. But, the best way of all, is to determine the combined resistance and reactance, then apply the voltage and then...
  10. K

    diodes

    What diode does it take? Is it .7V or or less than that to turn a circuit off.
  11. K

    Direct neutralization

    Inductors can self resonate because of their interelctrode capacitance. Neutralization is an attempt to neutralize interelectode capacitance with an inductor. Typical of higher frequency circuits. But their performance is bad due to poor engineering and poor production. Almost they don't work...
  12. K

    Direct neutralization

    Some transistors have a collector to base capacitor, but no inductor. Does that mean a single capacitor is acceptable and that sometimes neutralization is better? Would it depend on the frequency?
  13. K

    2V high current power supply for homopolar motor

    A single piece of wire can have a very low resistance, but 200 to 300 amp requires a higher voltage.
  14. K

    HELP NEEDED WITH DC POWER NOISE

    Just connect a 12V battery to the input power connector. To be sure, use an oscilloscope to verify that the adaptor connected to the camera produces 12V regulated. If it's 12V regulated, then try a higher capacity battery.
  15. K

    Increasing the DC 5V 250 mA adopter volt & amp.

    I think you can substitute a transformer and rectifier for capacitors and diodes if the power requirements are not high. But it would require many large capacitors and isn't worth the trouble. Generally you would require a transformer, rectifier, and voltage regulator.
  16. K

    transistor biasing

    Okay, I understand the stability with that biasing. Does that mean that there is little versatility with a 2N3904? Signal amplifiers require several stages of varying amplitudes and load impedances. Do you recommend different transistors all operated at their data sheet typical values?
  17. K

    HELP NEEDED WITH DC POWER NOISE

    Replacing an AC adaptor with just a series of small batteries is probably not good enough. A larger capacitor battery is what you could try.
  18. K

    transistor biasing

    A voltage divider bias at 10 times the current creates a low impedance for the signal source. An emitter resistor 1/10 the collector resistor is only a gain of 10. A single pole RC will reduce the critical frequency %70.7 and the bandwidth small. But given the inherent voltage changes in a...
  19. K

    transistor biasing

    What is the lowest current a 200mA transistor should be operated at to prevent distortion caused by bias drift?
  20. K

    frequency meter

    The signal can be converted to a clock signal with an opamp. A counter will set the last bit after a number of clock pulses. This bit can be used to power an LED, which will flash. An analog voltmeter or digital voltmeter can measure AC up to a maximum frequency and amplitude across a capacitor...
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