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  1. K

    Filters

    What is the limitation of using filters that have better attenuation than capacitor and inductor filters?
  2. K

    Car battery circuit design - comments, feedback?

    Another way to design the circuit might be to use a 3 amp NPN in series with the battery, and a 200mA PNP transistor in series with it's base to get a constant source of current to the battery.
  3. K

    Car battery circuit design - comments, feedback?

    I'm sorry, the circuit looks good. The 3.3 ohm resistor isn't power efficient, but maybe it can be replaced with a circuit.
  4. K

    Car battery circuit design - comments, feedback?

    I misread the original circuit. But I don't think a 200mohm resistor would see a voltage drop, unless it's a high capacity battery.
  5. K

    Car battery circuit design - comments, feedback?

    The original circuit posted seems to operate by switching on/off rapidly. Is that how it's operating?
  6. K

    question about Low Pass Filter

    Phase shift oscillators produce 180 degrees phase shift using cascaded RC stages. Maybe the components are chosen so that each stage is independent of the other and reduces the loading effect, which would keep the phase shift at 90 degrees at best.
  7. K

    Transistor collector current

    Low current biasing seems like a problem also. It only takes 200 mV before a transistor goes into cutoff. I have made simple cirucits that are just DC biased only, and have watched the DC bias drift by 200mV. But my test lab uses 7805 and 7812 voltage regulators and they're used, and so were the...
  8. K

    how can stabilize the mosfet's drain current help (linear amplifier)

    Doesn't the top MOSFET receive a larger signal than the bottom MOSFET? They operate in parallel, but have inputs of different magnitude, and outputs of different magnitude. This means that the MOSFET's can be damaged easily if the circuit isn't built right with new components.
  9. K

    zener diodes

    A zener diode has low output impedance, like a battery, so you have said before. But even being a shunt regulator, the voltage isn't good enough to act as a voltage regulator. Otherwise a simpler circuit using zener diodes would substitute for a voltage regulator, with a little waste of power.
  10. K

    zener diodes

    My mistake. Zener diodes are for voltage reference. The reason that they do not take the place of a voltage regulator is because their voltage isn't stable enough to accurately regulate a changing load.
  11. K

    zener diodes

    How would a zener diode be used in a high voltage regulator. Besides not being used to regulate the output, it would only be used in biasing the circuit. Most circuits don't use them much for biasing.
  12. K

    zener diodes

    Why do voltage regulators require zener diodes? Can't circuits not use them? They can't be very effective with a low impedance load.
  13. K

    Amplification and loss

    But shouldn't loss, as in the way of resistors be avoided. Of course discrete component circuits use them, but isn't it because of the necessity to complete the design. It's a way of interfacing circuit sections and is a concession in a design.
  14. K

    Dual battery Dual charger board with IO monitor output

    230 Vac is very high voltage to charge 12V batteries. Commercial 12V battery charges use 120 Vac and have designs that are too difficult to be redesigned. You might take a 12V battery and create a circuit to charge a 9V battery, so you will know what basic circuits will be required. You could...
  15. K

    opamp roll-off

    Low frequency opamps are more suitable for low frequencies than high frequency opamps? I'm not so sure because opamps have a bandwidth that extends to 0Hz. A high frequency opamp would maybe incorporate newer technology bipolar transistors, and maybe extra transistor amplifier stages to make up...
  16. K

    Neutralization

    Do IC's employ any passive circuits to reduce base collector capacitance? Why don't all high frequency circuits use base collector capacitance neutralization?
  17. K

    Alternator Basics

    Inductors produce a magnetic field, just like a magnet. I imagine magnetic based generators are still being used because of their advantages.
  18. K

    DC/DC Converter (the proper diode)

    What diode couldn't you use in a DC to DC converter? Designs are mainly based on operating charactersitics. Most common diodes switch fast for many circuits, including DC to DC converters.
  19. K

    DC/DC Converter (the proper diode)

    A fast switching diode might not be necessary for a DC to DC power supply. Schotkey diodes have a P region that is just metal, don't quote me. But the diodes you want have the voltage and current specifications that are just adequate. Using high current diodes, or low current diodes at their...
  20. K

    IC's

    Nothing I've read describes the drawbacks of not operating transistors under normal biasing conditions. Such as turning a transistor on and off is not the same as a transistor operated linearly. Using transistors to control gain by creating impedance seems not to be good design, although IC's do...
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