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  1. walid1

    simple question about batt chargers

    Hi all my friends When somebody build a batt charger that stop charging when batt full, he must use a comparator to compare batt voltage to some referance voltage.. when i conect a 3 volt batt to 5v power supply and wat to measure the woltage across the connection, what would it be? i ask...
  2. walid1

    Plants Watering Watcher-2 by Audiguru

    Hi all you are not respond to my last question, so i'll do more efforts to simplify the picture to myself, but still need your help. The table shown below is a cut and eddit from the datasheets of MC14093B. From this table I understand the following: When Vcc = 5 vdc, this gate considers...
  3. walid1

    Plants Watering Watcher-2 by Audiguru

    I agree with you that R8 reduce the max resistance between the probes, but R2 is not. R2 do another job, I think its function is as follows: Assume R8//soil resistance is very low, say 100 ohm (moisture content is very high) Our main ocs. changes its state every 250 micro sec (f=2KHz) If logic 1...
  4. walid1

    Decreasing bug antenna size

    can you please put your circuit for others to look and think abput it.
  5. walid1

    Plants Watering Watcher-2 by Audiguru

    Hi audioguru, thank you for everything (1) If we ignore, for a moment, the formula you gave me later to calculate freq, and concentrate on the statement you told me:((A Cmos Schmitt trigger switches when its input voltage is fairly close to zero volts while an ordinary Cmos oscillator switches...
  6. walid1

    cd4093

    use google get datasheets and read it
  7. walid1

    Plants Watering Watcher-2 by Audiguru

    Hi all Now I can move to another part of this complex (at least for me) circuit: In Fig. plants2 shown below I cut this part of the circuit because I think that this is a stand-alone osc. In his description, Audioguru did not tell us that gate IC1-B is a stand-alone osc, he said that this is a...
  8. walid1

    Plants Watering Watcher-2 by Audiguru

    Hi all my friends, i miss you all, it is good to back In the Fig.plants1 shown below there is a part of the circuit, this part is the IC1-C work as 2 Hz osc. As the author said. Pin 10 is connected to 3v Vcc R3 = 3.9M R4 = 100K C4 = 220n D1 = any small signal diode The designer wants that the...
  9. walid1

    op-amp low frequency pulse generator

    Hi audioguru yes this is true, i hope that you always teach me.
  10. walid1

    Resistance wattage in series

    this is excellent answer thank you audioguru
  11. walid1

    op-amp low frequency pulse generator

    Hi audioguru First thank you very much for your time with us I disagree, long time ago we have taught that caps are approx. short circuit during the charging or discharging process, so it connects pin 6 to ground... What u mean by snap action and hystreisis, i know that snap is a very quick and...
  12. walid1

    op-amp low frequency pulse generator

    hi audioguru I think that u mean pin 5 not pin 3 You may mean the internal (inside the IC) transistor. This is OK, i calculate and understand it but i have question: now let the o/p at pin 7 is 6volt then the voltage at pin 5 = 4v, if pin 6 is at ground, the o/p at pin 7 will remain at 6v. to...
  13. walid1

    Speaker - frequency and impedance

    this is a good and simple answer, i understand it , thank u audioguru
  14. walid1

    Speaker - frequency and impedance

    Hi guru you deal with us as we a big experts, u must simplify your answers i'm hardly understand u. u must take a low level persons (like me) into your account. thank you
  15. walid1

    op-amp low frequency pulse generator

    Hi guru, thank u very much no it is 6 volt (4 x 1.5V batt), the +ve terminal is 6V and the -ve terminal is 0 V. From where u get the + and - 9 volt u want to say that a "pull-up" resistor connect the point to +batt and the a pull-down resistor connect a point to ground
  16. walid1

    op-amp low frequency pulse generator

    Hi audioguru, thank u very much for your kind answer. (1) pin 5 always connected to the voltage divider formed by R1 and R2 and so it is always at 3v potential, correct me. (2) How u reach these numbers, +-2.7v (3) What the values of the o/p at pin 7? It is the first time for me to hear about...
  17. walid1

    op-amp low frequency pulse generator

    I understand the 555 timer IC when used in its astable mode as an oscillator, but the one shown below i need some help in: (1) how this oscillator work? (2) the function of the diode? (3) how to choose the components values to achieve some freq.? (4) What the formula used to calculate the freq...
  18. walid1

    Transformer Winding Sequence Question

    hi your question is very important for me also, and i wait the answer, but please send the full datasheet to ren_ADD to enable him to answer. thanks
  19. walid1

    Question about Ground Loops

    Why you enlarge the problem, try to forget the datalogger for a monent, my question is very simple i ask if you work in TV corporation and you notice that there is some bars in the picture and a hum in the audio and u want to prove to the others that there is a ground loop what you tell them and...
  20. walid1

    a regular transformer

    Hi indulis, I'll concentrate on this air gap, what the distance? and how the energy stored in this gap? thank you
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