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  1. walid1

    Wireless telephones

    I know this link befre and i store in my desk all what he writes it is for Danial it does not talk about cordless phone the way i wantbut thank you tnk2k
  2. walid1

    Google before posting

    I'm disagree with you, for beginners like us, it is diffecult to search and facing the huge quantity of information and easier to ask Also it make this community very rich I think there are  many persons who only read what we write and benefeted from that so don't worry at all yours WALID
  3. walid1

    Oscillator drift

    I read in a pdf file what appears in fig.oscillator drift below. as you see there is 6 points to take into account to make the osc. stable, I'll concentrate on the first one labled (a); the c/L ratio. what I want is to explain it numerically for FM 100MHz. thanks.
  4. walid1

    switching diode

    Welcome Mr Eng_Hussein
  5. walid1

    PNP and NPN replacements

    I an not so familiar with PNP type transistor. when I see a PNP tran. in any circuit like one that shown below that using a PNP, I immediately think to replace - at least in mind- with NPN. If I want to do so I must invert the power supply. is this what must to do or there are many other things...
  6. walid1

    What this circuit do???

    Please Audioguru tell me how to calculate the freq. of the NAND schmitt in the moisture content detector the first one gate that work as an oscillator you answered me before abot two inverters oscillatoe i want like that answer thank you very much power 10000000000000000000000000000000 walid
  7. walid1

    Wireless telephones

    Yes I'am always search using google before I ask but may be I have bad luck or  may i search in wrong way. I wat now to use your link and see if it help me I thank you very much WALID
  8. walid1

    Zener diode threshold voltage

    Thank you audioguru it ok.
  9. walid1

    12 volt battery charger

    Tank you but i need to answer the remaining questions
  10. walid1

    Mains OFF senseing

    yes exactly as in an emergency nion lamp
  11. walid1

    Wireless telephones

    This site is good but not excllent, I see it befor, it provide a surface info. I want info enable me to identifiy the TX and Rx sections and isolating them and using them say as a walki-talki, or eabling me to make a hand set of different device see another main one, like this....... I hear...
  12. walid1

    Transformer

    I asked this question before at this community at: http://www.electronics-lab.com/forum/index.php?topic=4264.0 you can look at it.
  13. walid1

    What this circuit do???

    Thank you very very much audioguru, it is helping me very much. (1) Gates come in two series, 40xx series and 74xx series, I read somewhere that the difference is that 74xx series working on 5vdc only where 40xx series can work up to 18vdc. Is it right? (2) And also I read that 74xx series are...
  14. walid1

    Mains OFF senseing

    I need a circuit that composed from a 220 to say 12 volts transformer then I rectify this to DC and then connectes to some transistor citcuit. this transistor citcuit must sense the existing or not of the 220vAC. if there is no 220volts the circuit o/p is high and vice versa. thank you for your...
  15. walid1

    Transformerless power supply discussion!

    Thank you Alun But I need more explinations if you or other person can. thank you all.
  16. walid1

    Zener diode threshold voltage

    If I have 6.8V 0.5W zener diode, what the minimum value of the applied voltage to make it ON. thanks.
  17. walid1

    12 volt battery charger

    Hi all The circuit shown below represent a 12 volt battery charger from "Sam Electronic Circuits" and I have some questions about it: (1) I noticed in this circuit and all charger circuits that they omit the smoothing cap after the rectifier, why? (2) Q1= BTY79 or similar 6A SCR and Q2= C106D ...
  18. walid1

    What this circuit do???

    how you calculate it (10 Hz)? please it is important.
  19. walid1

    switching diode

    yes i use google and have 993000 results i go to see if this help
  20. walid1

    Transformerless power supply discussion!

    Hi audioguru Thank you very much for your very good answer, especially that part about D1 which helps in discharging the cap C2. Now, I use Electronic Workbench EDA software to simulate the circuit shown below as Fig.PU1. I noticed that the readings are dependant on R_load value. At low values...
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