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  1. K

    Designing DPLL with 555

    Most PLL's are sinusoidal and their VCO's analog. A 555 timer is a logic device with a discharge transistor, level setting resistors, and a capacitor. It only produces a variable time pulse width.
  2. K

    Designing DPLL with 555

    That is how it is described to function. The 555 timer VCO is only part of a PLL. The control voltage directly affects the threshold voltage and indirectly affects the trigger voltage. Increasing the threshold voltage creates a wider pulse which is a reduced frequency.
  3. K

    Solid state...transistor amp design problems

    A high current push-pull amplifier at the output will produce sound from a high impedance speaker, but the amplitude will be low. A higher voltage supply will allow for greater amplitude, and adding transistor amplifier stages will produce greater amplitude. The input input impedance to the...
  4. K

    Linear's ideal diode in a full wave bridge rectifier.

    You could use these devices for a bridge rectifier or full-wave rectifier if they have P channel and N channel MOSFET's. However they might not be as accurate since the output of a full-wave rectifier is not regulated. These MOSFET diodes regulate Vds in response to a change in current.
  5. K

    Dual Tracking Supply Design Not Working as Expected

    If Vout is the regulated output, then these are the changes to the design. The rest of the circuit might be okay.
  6. K

    Dual Tracking Supply Design Not Working as Expected

    Okay, if J2 is the output, then Q1 needs to be an NPN and Q3 a PNP. The emitters are then connected to Vout. Q2 needs to be a PNP, Q4 an NPN, and their emitters not at ground, but V+ and V- respectively.
  7. K

    Dual Tracking Supply Design Not Working as Expected

    seanacais, is the unregulated voltage connected to J1 or J2. Are you using the corrrect transistors for Q1 and Q3? They are the same transistor, except one is an NPN the other a PNP.
  8. K

    Dual Tracking Supply Design Not Working as Expected

    Assuming you have replaced all of the opamps, the uneven voltage distribution seems very even. Since the circuit is designed by yourself, it may easily be the wrong offset voltages of any of the opamps, and the voltage distribution only looks to be half. A saturated opamp is easy to identify.
  9. K

    Transistor biasing help

    Lower beta transistors used for power applications have low value emitter resistors. Since it is difficult to use low value base biasing resistors, because of loading, the base current may be 1/3 the current of the biasing resistors. So the voltage gain is lower than the collector resistor...
  10. K

    power amplifier- pls help me

    If the opamp is used as the output stage of a pulse width modulated signal, then the motor will be controlled by pulse width modulation. However, since that opamp can drive lower impedance loads, it might be possible to simply add a push pull amplifier.
  11. K

    C programming

    Hello gogo2520. I have read that microcontrollers can be programmed in C with compilers adapted for certain microcontrollers. Doesn't that make it easier to create larger and almost as efficient microcontroller programs. I know of other languages that can be used, but they would not be as...
  12. K

    dual-output transformer

    It shouldn't have any effect on the circuit. But I'll guess some loads can afffect the voltage. And also it mostly assumed the load changes the impedance not affecting the voltage source.
  13. K

    PWM Without PWM IC

    The circuit is a basis for a voltage regulator. But voltage output will not be as it is set to be. The voltage regulation can be improved with an output capacitor.
  14. K

    dual-output transformer

    The circuit looks okay. But use normal power supply diodes because the average current could be too high for some diodes. You can estimate the amount of average current, but any power supply diode will be good enough that circuit.
  15. K

    noise cancelling circuit

    There is a polarity switch S1. It may also need a variable resistor circuit so the user can have an adjustment depending on the type and intensity of outside noise.
  16. K

    noise cancelling circuit

    The theory behind it is to reduce what is in the original transmission. If it's not there, aren't you amplifying external noise?
  17. K

    noise cancelling circuit

    The idea behind the noise cancelling headphones would appear to be only effective under certain conditions. Is a mic placed outside the earphone the way they are sold in stores?
  18. K

    Is it a hartely oscillator??

    A buffer circuit is needed. Most oscillators I've seen have a whole lot of transistors. There only a few capacitors and or inductors used to resonate.
  19. K

    LC tank circuit frequency

    It could. Maybe it's only in some receivers or transmitters.
  20. K

    Is it a hartely oscillator??

    The hartely oscillator has many drawbacks as do ther other simple oscillators. It could have to do with the resonant frequency of the LC and the ability to get high enough gain. It may also have to do with any change in load conditions that could prevent or stop oscillation.
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