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  1. K

    741 Offset voltage problem

    Everything lookks good. The supply voltage is a little low which means that it will have a narrow range of operating conditions. But beside that, do you know how to adjust the pot. In your case, since you are using 13v and ground, you will need to equally bias the inputs at 6.5 volts with a...
  2. K

    RC time constant

    Perhaps the most overlooked by most enthusiasts is the RC time constant. The best way to determine if your circuit is good is to compare the time of the RC with the time of the signal. If the time of the signal is short, such a ramp of a square wave, the RC time looks very long to it. If the...
  3. K

    differentiator

    You know the current is C dvdt. If you have a current you have a dvdt. The dvdt is the rate of change of the voltage. And what you are saying is that an opamp integrator uses this concept of a 0 dvdt to charge the capacitor. But of course the current is not zero and the capacitor's voltage is...
  4. K

    helping in testing a bcd decoder

    What is funny is that you can take 10 seperate LCD circuits for the numbers one through ten and select which one goes to the LCD. A cascaded array of data selectors can be used.
  5. K

    differentiator

    How else do you get the rise with time. Something about the DC applied to a capacitor produces a ramp. But what you are saying is constant current. I don't care what the current does, I know it has a curve too. I care what the voltage does. And the voltage rise is not as linear as it approaches...
  6. K

    Temp. Compensation for linear power supply

    If yours is like mine, you probably have a regulator that is not performing well. Mine did that just before the voltage went completely down after few minutes. I have since replaced it and it works fine.
  7. K

    Low-pass Filter?

    Take a low impedance RC circuit, tag on a high impedance RC circuit, and there you have a 40db circuit. I believe they use this concept in the phase shift oscillator.
  8. K

    My girlfriend is getting into electronics

    You are right on the money Alun. Mathematics, not Physics, is the key to understanding electronics.
  9. K

    differentiator

    Okay I agree. A constant current. But remember too that because the input is DC the output is DC. Once you get the DC input, you should get the DC output but the capacitor has to charge and it charges following the capacitor charging curve just like when you apply a DC to a series RC.
  10. K

    differentiator

    Just for fun, the differentiator performs the derivative function mathematically. It turns a certain rate of change into a voltage level. The capacitor is in the gain circuit of the opamp and the amplitude of the input will be determined by the capacitive reactance. The integrator is...
  11. K

    Low-pass Filter?

    Something worth noting is that there is a difference between low pass filtering and active filtering. I am not saying that they are wrong, only loose in how they describe the circuit. Whenever you use active filters, you are using the reactive component as the gain element. So your voltage is...
  12. K

    Transistor distortion and reducer circuit

    Audioguru, that diode reduces distortion by means of it's variable resistance counteracting the transfer curve of the transistor. Transistor distortion is very small and is a result of how the beta changes from let's say 150 155 160 which is good to 152 155 158 which is less good because it is...
  13. K

    bidirectional re

    I want someone to verify the bidirectional re of a transistor. I could not find the data in my book so I was left to guess. I wondered why you could not have a larger signal on the base when in fact the signal originates at the emitter. It could happen right. Not likely in this situation. The...
  14. K

    Correct way to Measure Power Supply Amperage

    The correct way depends on the change in current with repect to the changing load. In other words the current waveform that is produced as a result of a changing load. A DC circuit can be simulated with a single resistor, the signals within the system change the DC current. Now that you have the...
  15. K

    tranasistor with amplifying factor 200

    I have often wondered if there is a device that would cancel the nonlinearity of the transistor. But then I realized it would then be incorporated into the transistor if that were the case.
  16. K

    tranasistor with amplifying factor 200

    What I said about the transistor is all true. But the only thing is that I choose midcurrent as it is a value that rightly falls mid distance between the corresponding maximum values. When they talk about midpoint biasing, they mean the Ic sat. is what your design is and not the data sheet. It...
  17. K

    PCM Speech CODEC

    What's this, problems with the clock. You shift your phase back upstream where you have the sine wave oscillator. A series RC will give you the phase difference. Then the sine wave oscillator is converted to a square wave. This is the method of choice anyhow.
  18. K

    tranasistor with amplifying factor 200

    I'll explain it. The voltage and the current of a transistor dictate the beta. Lower current transistors tend to to have the highest betas. Almost any transistor can give you the desired beta. Now for the interesting part. There exists what is called the Q point. Simply stated, it is a certain...
  19. K

    complimentary symmetry amplifier

    Often misinterpreted as a pushpull, this amplifier gives the highest voltage gain possible whereas a pushpull is just a current amplifier with a voltage gain of one. http://www.radioelectronicschool.com/reading/reading26.pdf I believe this is the basis for opamp gain. There is also a pushpull...
  20. K

    Help needed for Timer Circuit

    A simple RC circuit has it's limitations with repect to accuracy. I would not investigate wave shaping techniques. It is my opinion that you can't correct for the inaccuarcy of a capacitor through the use of semiconductors. A capacitor is just perfect in every sense when it comes to semiconductors.
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