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  1. K

    pulse width modulation

    When the output of the second inverter is high, it will charge the capacitor high, which sends the output low. You have the discharge of the capacitor which allows the ouput of the second inverter to go high.
  2. K

    was Re:Ir-remote Now is: Op Amp discussion

    It seems simple enough to me. The input can be grounded or grounded through a resistor. There is the case where you want the input bias currents to be the same, for a zero voltage output. This is the resistor which will allow you to affect the input bias current. I think the resistor is for...
  3. K

    please explain ??

    Sometimes I think that the values chosen for RF applications are just in the neighborhood of being correct. You could narrow your design work quite a bit by choosing component values that are within reason. All you have to do to get it close is to know the impedance and of course properly DC...
  4. K

    Power MOSFETs

    A high gate capacitance can be a misleading topic. I don't think that it actually charges like a capacitor, but exhibits the frequency response. I may be wrong. What is true is that the gate capacitance will keep the VGS from developing at a higher frequency. By the way, isn't the transfer...
  5. K

    pulse width modulation

    I think I understand the operation of the circuit with one inverter. But why use two inverters. The last circuit only uses one inverter. The operation with two inverters doesn't make sense because the output of the second inverter would tend to stay high. Could somebody explain why one or two...
  6. K

    OUTPUT IMPEDANCE

    This is simply the resistors and transistors at work. The transistors are most likely driven by the signal as opposed to being left open. In other words you won't be left with a signal trying to drive the collector of a transistor. The change in voltage therefore produces a change in current...
  7. K

    increment/decrement counter

    I think that is a shift register with a parallel ouput going to the LED's. The input to the register is pulled high. Each pulse will send a high that migrates through the shift register. At the end, all the LED's are lit and the device needs to be reset. This is a way of counting clock pulses...
  8. K

    Voltage Matching

    You might consider that this is a signal that is biased around 12 volts. Use a transistor which will give you the voltage you need under higher current. I think you need a high current transistor because it will allow you to get a reasonable amount of gain. In other words, let's say the load...
  9. K

    Testing Components?

    Test it the way you would with any other component; with a bridge circuit. You have to know the frequency it was designed for. You might find that the device is so accurate that you would be looking at very small variation. But this is what a bridge is designed for. You might start with the fact...
  10. K

    BCD 74HC390

    A modulus 10 counter uses flipflops and some associated logic to give you 10 stabile states. Each clock transistion will give you a change in output. There is a guy in the microcontroller section that is going to use a johnson counter to control the triggering of a one shot. With a latch on the...
  11. K

    555 timer help

    A 555 timer is a simple circuit that includes voltage divider resistors, two opamp comparators, a transistor, and a flipflop or SR latch. The disadvantage of this circuit is the extra components that are not used in some applications. I am not sure what particular function involves the use of...
  12. K

    transistor uses

    I underatand what you are saying, but a FET gives you the same result. A change in voltage divided by the change in current gives you the impedance. The question is , how much change in voltage will give you the change in current. With a FET, it's dependent on the gm. Maybe the gm could be any...
  13. K

    EMI measuring tool/ detector. how to build?

    EMI can be generated when an inductor comes into close contact with another inductor. I have always suspected that for this reason a coil can't be located too close to a capacitors plates. I think I have even seen where this is a problem, but I'm not certain.
  14. K

    pulse width modulation

    Can anybody see the problem with analyzing this circuit. There is a peculiarity that exists. The first ciruit. What makes the output of the first inverter go low when it's high? I think it may be the high to low transition of the second inverter. This means the low has to go through D1 and the...
  15. K

    pulse width modulation

    deleted
  16. K

    Transistor Audio Filter Design

    Any collector resistor contributes to gain. Most of the time, the capacitor will contribute to voltage reduction instead of gain because the parallel elements make the capacitor independent of gain. When you go to the series circuit, you can't make anything independent so you are left with...
  17. K

    transistor uses

    I would just stick it into a beta tester but I don't think it work. You know that it will be a function that has linear properties.
  18. K

    pulse width modulation

    deleted
  19. K

    TTL inverters

    Could someone explain this circuit in terms of the overall design. Why do they use a low current source and a high current sink? Why do they use the totem pole, which has an emitter follower and a common emitter. The idea I have is that logic is designed to handle the 0 to 5volts. This is a good...
  20. K

    transistor uses

    I would be talking about diacs or triacs when I say a 5 layer device. The anode of the zener would be the base. The anode of the diode would be the base. The cathode of the zener would be the collector and the cathode of the diode would be the emitter.
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