Search results

  1. walid1

    AM reciever mixer

    Hi the folloing fig is the front end of a simple AM radio reciver It contains the AM ferrite antenna and two variable caps, one connected // to the primary coil of the antenna and the other // to the primary coil of the red (local oscillator) transformer. AM sig freq from 530 KHZ to about...
  2. walid1

    Are datasheets important?

    First I used the dictionary for translation so please forgive that there were some errors in language OK, I'm engineer in communication and control, 5 years in university after high school , Despite this, I feel myself as if I'm small and stupid pupil when discuss GURU. I know many of...
  3. walid1

    Are datasheets important?

    Hi I believe that Mr. AUDIOGURU is a big  R&D Engineer, and he is the best one i meet in a forum OK i'm not so good in electronics, but I can distinguish between person and person, and I know from the answer the person's abilities. Therefore, I ask everyone to deal with Mr. AUDIOGURU...
  4. walid1

    Frequency response for a transistor amp.

    thank you guru Summary of what guru said: (1)Pre-emphasis: a process is being carried out at a transmitter to boost high audio frequencies (2)De-emphasis: a process is being carried out at a reception side to cut the treble audio frequencies back down to normal and cut hiss at the same...
  5. walid1

    Audioguru FM Tx

    Hi GURU From the above values of C1 and C3 and the corresponding values of the freq they can pass, I deduce that u assumed or calculated the i/p impedance of the first stage and the second stage to be 12K. For the 2nd stage: you did these calculations: So u concluded that Zin = 21.6K RC filter...
  6. walid1

    Frequency response for a transistor amp.

    Finally, after a long discussion with Mr. Audioguru, i discover that the frequency response is a relation (curve) of freq vs voltage gain (Av). The following Fig is the 1st stage of guru's FM Tx: Av = RC/re, this is assumed at very high freq that makes Xc4 = 0 so shortened the RE But at audio...
  7. walid1

    Problem on two parallel plate capacitor.

    I think but not sure the following: You know that C = e0 (A / d) where A is the area of the capacitor plates, and d is the distance between them. e0 is the permittivity of free space (8.85X10-12) a) Vo is still as lt is cause the relation did not affected by batt voltage. the capacitance of a...
  8. walid1

    Ft of the transistor

    Hi I read carefully Kevin Weddle's reply an Audioguru's reply, but sorry i can't understand anything, i don't know why. Also I can't ask questions because i don't know about what to ask! Despite that will ask : how 20v and the supply voltage is only9v????
  9. walid1

    BJT biasing formulas

    Thank you guru, I think that this is a big subject it is better to focus now on topics simple and and when finished turn to the more difficult topics. I want to tell you that a great honor for me to debate with you, you great wealth of scientific.
  10. walid1

    Ft of the transistor

    (1)I know that it is a common-base amplifier because of C5 connected between base and GND and at FM freq it short that base to GND. But I did not know about the transistor's alpha, can u please tell me something about it? (2)I attach your FM Tx, I look at Q3, it is a 2N3904 transistor and it...
  11. walid1

    BJT biasing formulas

    Please I want further clarification on this point, I hope to support that with examples and illustrations thanks
  12. walid1

    What happen when downloading the previous stage?

    A very good example thank you guru
  13. walid1

    infrared help

    Hi I understand how FM, AM and PM modulation takes place If allowed to give us an idea of IR modulation thanks
  14. walid1

    What happen when downloading the previous stage?

    thank you guru from what you said, if the o/p impedance of the first stage = 9K and the i/p impedance of the next stage = 1k and the signal is 1V only (1/10) of that signal reach to the next stage that is 0.1 volt. If so, the word dowenload be inappropriate because I understand that the...
  15. walid1

    BJT biasing formulas

    Hi I'll back to the first design; C_E without CE. I think in the past that increasing the value of Ic have better property to get higher o/p power, and I was prefering -according to this- to design circuits with higher Ic values GURU explained that this was a mistake and from my discussions...
  16. walid1

    What happen when downloading the previous stage?

    hi Today, I sat thinking at this point, what happens when the i/p impedance for the subsequent stage is less than the o/p impedance of the past stage? Please clarify the idea Thank you
  17. walid1

    Ft of the transistor

    Hi Ft is the freq at which beta (hfe) = approx 1 for 2N3904 transistor I found that at 300MHz, hfe = 1 frome the same datasheets i found the following curve: look at the red curve at 300MHz, hfe = 5 dB 20 log (hfe) = 5 hfe = 1.8 Now at FM freq (say 100 MHz) and from the red curve, hfe =...
  18. walid1

    The relationship of Amplifier vs Power vs Frequency

    Hi guru I can use SWCAD III to see the freq responce of a C-E transistor amplifier circuit, But I want to know how are calculated or how is expected during the design process Can you please explain to me thanks
  19. walid1

    Salt-taster

    thank you guru it is a complete answer
  20. walid1

    Salt-taster

    Thank you guru I understand you The author said that the voltage drop on a red led is 1.6v Is this standard value I measure it , it was 2v and sometimes 2.2 volt thanks
Top