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  1. K

    sensitive low frequency filter

    The reason it works that way is because the external current dictates the voltage. This is, apparently, always the case with an opamp. I think it's interesting that it appears to work, when you should actually bias it right. You know, of course, that the opamp will work differently depending on...
  2. K

    sensitive low frequency filter

    Both. Where is the ouput bias? You need a resistor to ground or a negative voltage. What you have is something other than what is intended for an opamp. What happens is an increase in voltage on the emitter causes an increase in voltage on the base. The base has to be able to maintain it's...
  3. K

    sensitive low frequency filter

    This circuit is not biased properly. The load impedance of the opamp is too high. It will work in the end, but the response will not be that of what is intended for an opamp. You have to DC bias it correctly before you use a signal. The current ouput of the first stage is simply to low.
  4. K

    handy tip for intefacing your PC with projects

    Is the data transfer in a parallel port unidirectional? Does anybody experience how the newer generation of Windows makes it hard to get to the C: prompt? I have seen limitations using the MSDOS prompt. Sometimes I don't even want Windows to start.
  5. K

    transmitter/reveiver design for fiber link

    A train of waves is different from the problems associated with a coaxial cable. Standing waves aren't a problem. This is the reflection that is talked about. I think the standing wave can only cause a problem when the changing signal produces different standing waves, thus affecting the input...
  6. K

    help about inverters

    What you are referring to is that the power in equals the power out. This is true. I constructed a voltage multiplier with some results. I replaced both of the bottom capacitors with larger ones. The load was connected final capacitor to ground. It turns out that you have to decouple to measure...
  7. K

    transmitter/reveiver design for fiber link

    I have a question. I have read, I believe, that wave propagation down a transmission line results in a train of waves. Is this true? It would make sense that a bit originating from a long distance and appearing at the other end would not happen. Instead you have a train of waves on the line at...
  8. K

    transmitter/reveiver design for fiber link

    You don't even need modulation if you don't want to utilize the short time base. The question is, where do you want to save time. In modulation, what you are doing is compressing 5 minutes worth of data into 30 seconds. 30 seconds is the transmission time. In order to that, you have to already...
  9. K

    State Variable active filter

    I am aware of some of the problems with designing a circuit. You want one thing, but you turn around and end up negating it. You have meaing to the signal in one part, then you lose meaning when you make additions. I have an idea to correct for the nonlinearity of the transistor curve using it's...
  10. K

    Amplifier circuits

    I know that I am a little overwhelmed when it comes to the data on data sheets. They deal largely with external testing of the device. This is the way to go, but the schematic itself is left to guessing. I do find graphs useful when looking at it from an external testing perspective. I just wish...
  11. K

    help about inverters

    What you would be saying is that if there is sufficient current, the voltage would have to be high. The amount of current is dependent solely on the capacitors. The voltages of the multiplier are what they are. When you load the multiplier, it takes more sections to get the volatge. In other...
  12. K

    simple PWM

    I built a circuit similar to this and found that my relaxation oscillater did not give me good results. I used a NAND with feedback and a capacitor and resistor. The voltage I got was not stable enough to be considered a clock. This might be interesting to anybody trying to configure a clock...
  13. K

    help about inverters

    I would have to argue about current loss with voltage multipliers. The problem I saw is the number of diode capacitor sections needed to deliver a high current load.
  14. K

    transmitter/reveiver design for fiber link

    It is a very interesting experiment to send analog data down a fiber optic cable. The luck you would have could rival that of a cable. The only problem with cable is that you are limited to about 1 gigahertz. I think you might try to modulate demodulate the signal using the LED and the...
  15. K

    transmitter/reveiver design for fiber link

    I was refering to only digital. I was talking about sampling, but it does not require an AD. The data rate would still be 20k hertz too. This is just a way of using the high speed transmission. With modulation, though, instead of 5 minutes to transfer the data it only takes 30 seconds.
  16. K

    transmitter/reveiver design for fiber link

    The speed of the transmission is almost instantaneous. This means the data will be sent at the rate of 20k hertz or as fast as the data is present. You could also clock the data at a very high rate and get every last piece of the signal. This means you will have data that is extremely accurate...
  17. K

    timer IC

    Timer IC's come in a variety of configurations. Many are used to control clock functions in microprocessor based applications. They generate clocks and can be enabled or disabled. A clock is divided and can be can be used for clocking various devices at different rates and times. This in turn...
  18. K

    State Variable active filter

    A 40db per decade occurs at a high frequency and is the result of the transistor characteristics. Each capacitor section will give you 20db per decade. When you incorporate capacitors and inductors in various areas the db per decade can be tricky. I would first build the circuit, then determine...
  19. K

    author of the transformer article

    It turns out that my autotransformer did not have enough reactance to keep the power outlet from blowing the fuse. I did, however, keep the windings intact. The inductor that it turned out to be is a good power inductor with a less than perfect equation. If anybody is curious I will explain a...
  20. K

    Amplifier circuits

    I would not say the data sheets are clear. They tend to allow for many assumptions. Often they will show a test setup which is no good to the designer. They never show how the external RC fits into the schematic and how it will affect the gain and or bias. There are, I believe, key points that...
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