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  1. K

    Soldering Help

    Use just enough solder to make a dropplet effect. Use more solder as opposed to less. Use a flux and a hot iron. This get me by. Some say that too much solder creates parasitic inductance and it's true. It makes for a great filtering but of course that is just what the ear hears.
  2. K

    FM Transmitter

    That capacitor is an emitter element that has an impedance somewhere around the value of the emitter resistor. The only reason that it is not grounded is because it allows the inverted output to be fed back reducing the high gain capability presented by the tank circuit. The impedance of a...
  3. K

    Beginers OPAMP question

    An opamp uses transitors in the pushpull configuration to achieve high gain. One interesting aspect is that the difference between the inputs get amplified while a zero difference produces a zero ouput. Let's say you apply 5 volts to each input. Then you apply -5 volts to each input. The result...
  4. K

    no phase difference

    What do you want to do with the input signal. Amplify, filter, modulate with another signal, or change the complete nature of by adding a complex filter. Zero phase difference means selecting the right components. You can realize this even with a complex circuit as long as you can keep track of...
  5. K

    Ampliude and rate of change

    Is there any sort of modulation that uses the change of amplitude to give you a different rate of change. I know in AM the amplitude change is at the frequency of the message. But what about the amplitude of the signal itself. You know that whenver you gain a signal the amplitude increases and...
  6. K

    pseudo double-gang pots with transistors...

    That is an interesting article. I should have suspected they would go into detail concerning pots. I have not worried much about them, except for trying to obtain discrete values is sometimes frustrating. It easy is easy to see why you can turn 100 into 50 and at the same time turn the other 100...
  7. K

    Turn the lamp On & Off gradually...

    What you want to do is change the frequency. That is it. It is best to generate a new frequency based on a transitor with feedback. An oscillator if you will. Then just filter out the 60 HZ and you will be left with the frequency of the oscillator. This circuit is going to be used to control the...
  8. K

    pseudo double-gang pots with transistors...

    I don't quite get what you are saying. A gang pot must be a simple device. If you take 100 and reduce it to 50, the effect would be to reduce the other resistors by x amount. Sometimes it is desireable to have to independant resistor values. I don't get how you want to replace this with just...
  9. K

    AM RECIEVER

    Audioguru I just don't agree. I think the loudness is the voltage difference between any two consecutive cycles of the carrier wave. If you modulate a high frequency on a carrier, you will get the carrier to change at that rate. This is what the diagram shows and I agree with that.
  10. K

    need help building a scmematic

    I am not sure this will have any meaning here, but there is a way to generate a one shot from the occurance of the input. Take the output of a logic gate and add put an inductor to ground. This will give you a charge of 5volts for an amount of time.
  11. K

    Reduce output Voltage of Power Supply

    Yeah you can do that. It is a shameful waste of power but to get good regulation, set the resistors to 10 ohm. The only problem with that is the voltage is not now regulated. But you could add a regulator to the mix also. Unfortunately though you will have a lot of ripple still in the input. You...
  12. K

    lm741 schematic diagram

    What I want to know is about the input stage. It seems there is a constant current in there. You know how you can have +7 and +7 on the inputs and have a 0 voltage out. I think there is a transistor there that sets the initial current at the base of the two connected transistors. If you have an...
  13. K

    AM RECIEVER

    The voltage of the carrier does indicate frequency because a radical change in the amplitude of the carrier indicates a high frequency of the message.
  14. K

    Changing 12v to 24v with out a transformer

    Very interesting use of the opamps. This is a square wave oscillator I believe. It also looks like you have clamped a voltage. The diodes are shottkey not zener. If I am not mistaken the oscillation ocurrs at the mains frequency. That is the frequency being amplified.
  15. K

    AM demodulator diode

    I did some research to find out the diode is just there to get rid of the positive or negative cycle. It's the capacitor that filters out the carrier. If this is demodulation, wow how simple it is. You would tend to think that demodulation would help to remove the carrier rather than just...
  16. K

    AM RECIEVER

    It seems interesting that they call a diode and capacitor a demodulator. When in fact, the demodulator is just a capacitor filter. I think that since they remove part of the cycle with the diode they can say they have isolated the message. For the message will appear in the cycle that is passed...
  17. K

    Transformer ratings?

    I think you have misjudged the situation. This is a center tapped transformer. 50 VAC turns into 25VAC applied to each diode and 35 volt capacitor. 25 VAc is 35 volts peak.
  18. K

    AM demodulator diode

    How does this work. I can't see being able to change the frequency with a diode.
  19. K

    Transformer ratings?

    For a power transformer, you will always get the 120VAC on the input. This means you will have whatever voltage on the ouput that it is stepped down to. Loaded or unloaded. So, yes you can assume a maximum of 50VAC according to the capacitors.
  20. K

    AM RECIEVER

    There are a lot of different types of modulators. The simplest only suffer from lack of performance. It is often desireable to stuff as much information as you can in a certain time frame.
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