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Everything posted by walid

  1. Hello frome the datasheet of RX-3 i get the following application circuit and at the left side there is antenna and related component: My question is what the purpose of the transistor Q1? thank you
  2. hi I use a multisim-10 to simulate a VCO which intended for 106MHz freq output but the o/p is only 50 KHz as seen in the attached pic why?? thank you in advance
  3. I appeal to my friend audioguru to respond to the subject I waited for his reply for more than a week Thanks
  4. I discover the answer of the second question: the RMS value of the peak voltage = Vpeak/squre root of 2 and when we squre that root we get 2 which appear in the equation. i need answer to question 3 thank you very much
  5. Hello guys In the following link, http://www.electronics-tutorials.com/amplifiers/negative-feedback.htm the author speaks about how to made the necessary calculations to determine the transformer's turns ratio and also the LC needed for impedance matching a 50-ohm antenna to the preceding stage Regardless of some of the details that the writer is talking about, espicially his talking about the dc biasing and the o/p voltage swing, I will focus in the discussion with you on the method of calculating the turns ratio. Look at the fig: the author said: My questions are: 1)Are these calculations are true in general? 2) Why '2' in 2.Po = [Vcc-Ve]^2/R, i learn that P = V^2/R 3)Why [Vcc-Ve]^2, I think it must be [Vcc-Vc]^2 Eagerly awaiting your reply Thanks
  6. Hi Guru Thank you for attention What do you think of this circuit from: http://www.talkingelectronics.com/projects/27MHz%20Transmitters/27MHzLinks-1.html The author use a transformer then PI network filter for impedance matching the low Z antenna (50 ohm) to the very high (near infinity) Z tank circuit. I am a week ago, trying to understand, and I hope that you help me to understand Thanks
  7. what to do if the load is 1k only?? Do I have to replace the coil with a stepdown RF transfrmer??
  8. What the solution then?? Do I have to replace the coil with a stepdown RF transfrmer?? What is the turn ratio then if i want to match with 100K ohm load? thank you in advance.
  9. thank you guru Be sure that the resonance freq is 27MHz is the Zout = XC//XL; the parallel equivalent of the two reactancess (coil and ca)??? regards
  10. Hello guys The attached photo is a crystal oscillator it is a voltage divider config. but replacing the RC with LC tuning tank I need to know the out put impedance Zout?? Is it XC// XL at the operation freq 27MHz??? please help me thank you in advance http://NOTE: sorry L= 3.48 uH not 1.2 uH as in the circuit
  11. We have discussed several subjects did not find an old Please help
  12. Thank you KevinIV for reply my question is why and how filter amplify signals??
  13. Hellow, I build the following pi filter to match 100 ohm source to 1000 ohm load, I did the calculations based on RF Circuit Design Book As u can see at the center freq fc = 30MHz & Q=15 I had 3.771dB, I was surprised by where this value? this is amplification!!!! The second question is: If i want to match 1000 ohm source to 100 ohm load, Simply replace the capacitors, one must place the other, when i did so and simulate i had the following: [img width=680 height=478] Look!! -9.8dB at the center freq. can you please comment, how to match big source to small load without that bad attenuation thanks alot
  14. [glow=red,2,300]January 2007[/glow] http://rapidshare.com/files/9994391/Jan07.pdf
  15. I am sorry, my dear Ante,the last issue I have is February 2007.
  16. Hi Ann I wish that the dialogue is always reply point by point. I spend a long time in the preparation of the question therefore hope that the reply on the points that I'm asking about them specifically and not a general answer. The question that I wish to find a definitive answer for is : Why must know -ve resistance, and when necessary to developer in mind? thanks
  17. Here is another one http://www8.rapidupload.com/d.php?file=dl&filepath=39423
  18. If this is not forbidden, I have many of them and I can give you for the benefit
  19. I submit this electronic magazine as a gift to the best forum in the world http://www8.rapidupload.com/d.php?file=dl&filepath=39239
  20. I do not have the necessary equipment, but I submit this link to enrich the subject http://www.giangrandi.ch/electronics/crystalfilters/xtaltest.html
  21. Hi TO audioguru: (a) Clear from your talk that you agree with AN920 that this is not good design. (b) I thought that it is banpass filter. i think it is 3rd order because it is 3 elements filter. Let me look at the internet for further information on this filter. TO AN920 I have long believed that many of the designs are in a trial and error because of the different specifications of some electronic components from each other. (a) That is a very good and new idea, are you sure that Another crystal of the same value in series on the output work as lowpass filter? (b) Can shed further light on the use of crystal as a LPF. thanks GURU thanks AN920
  22. Thank you, I am very happy about your presence among us more than happy to answer, because I miss you and I intend to send a special message to you. I thank God that you are fine. Possibilities in Canada very large, but in Palestine almost nothing, we are therefore interested in those circuits, which can be dealt with. From the graph, I think it would be difficult to build a circuit to deal with temperature = 30
  23. Hi I found this circuit Saved in my PC (pdf formatt) and I do not know of any site obtained. This part is what concerns me now This part does not really care because I will focus on how to use transistor as heat detector. The writer wrote the following passage : My question: Is this talk true, I mean the resistance between collector and emitter is small at high temperature. Can this circuit activate the relay to operate at a temperature of 30 degrees Celsius for example? My friend who owned Machine chicken breeding (breeding) of the locally-made and wants to operate some internal parts when a certain temperature, can this circuit be used instead of the temperature sensor which is already not available (HERE). Thanks
  24. Hi An920 While I am looking into the Internet, I encountered the following firure from the Web site : http://www.k8iqy.com/qrprigs/2n215/2n215page.htm As you see in the picture C21 is less ten times than the upper C20, and this violates what we agreed upon in previous commentary. I think that this design done by senior scientists.
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