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Posts posted by solycutema

  1. Dear Audioguru,

    You were right when u said that the voltages are missing.

    I'm using DC power supply. I can't seperate the positive voltage and the negative voltage. From the DC male jack to the female jack, with a multimeter, i can get both the +ve and -ve voltage. But once i connect the two ends [the end that connects to com port on multimeter], the voltages reduced to 0.2volts. Why is that so? Pls help. Thanx.

    p/s sorry for troubling u this few daes. =)

  2. Dear AUDIoguru,

    Thanx for the input.

    These are my measured voltage:
    TL072 Pin 4 = -7.2V
              Pin 6 = -0.08V
              pIn 7 = -0.12V
              pIn 8 = +0.07V

    LM386 Pin 1 = +1.5v
              Pin 5 = +1.9V
              Pin 6 = +2.7V
              Pin 7 = +0.2V
              Pin 8 = +0.2V

    UA741 Pin1 = -6.9V
              Pin2 = -0.43V
              Pin3 = -0.5V
              Pin4 = -6.7V
              Pin5 = -6.9V
              Pin6 = -0.47V
              Pin 8 = +0.34V

    When i plugged in the DC supply, LED blinks contanstly. I hear buzzing sound continuously through the headphones. when i tap on the electret mic, the buzzing sound will tap also. what problem am i facing? pls advice. thank you.

  3. Dear Audiuguru,

    1) How do i know if i'm using a linear trimpot?
    2) Can i still add the 3.3k resistor at pin 3 to gnd of U5 if it is already a linear trimpot?
    3) Are there any other resistors on this circuit that i can change to trim pots in order to    change its functions/variability?
    4) Can you help me design a circuit whereby i can use a switch to switch to it? with C3 and C4 at 4.7nF in order to hear lung sounds? is it hard to change from my already done PCB? means i can swith from circuit A to circuit B by using a switch. Switching from low frequency to higher frequency without another whole new circuit. jz a switching device.

    hope to hear from  u soon.. need to finish by this week. =)


  4. Dear Audioguru,

    Is it ok if i use a 9V DC supplY? Used up many batts during the process of trials.. Cant afford too many.. =P

    I am also using a 6 pole switch... where only 4 are being used. i use it to seperate the positive n negative voltage.  is it ok?

    Am fabricating a new PCB in a few daes time. My previous attempt failed me... too small to solder my parts... many short circuits. *sigh*

    are u able to check my pcb for me if i upload here? hope to hear from u sooon. thanx.

  5. 7V for a 9V battery and with the low current of this project is a battery that is wearing out. When it reaches 6V then it is dead.

    Please measure and report here the DC voltage measurements to ground of the microphone, pin 1 of U1, pin 7 of U1, pin 6 of U4 and pin 5 of U5.
    Please look at the connections and parts values on the schematic again.

    The DC voltage for the points : pin1 U1 = 6.9V, pin7 u1 = 7.3V
    Pin6 U4 =8+V , pin5 U5 = 7+V
  6. dear audioguru...

    i dun think its the batt.... it still has 7V+.. =)
    volume min = LED flashes fast
    volume max = LED blinks steadily.... blue then red... blue then red.... (tick-tocks)

    i attached a speaker... theres sound... no howling..... (ticks tocks)
    i attached headphones... very loud *tick-tocks* according to the situation above..


  7. hey.. thanx audioguru..

    now it works... meaning there is sound output.... but theres a contanst *tick-tock* sound when the power is turned on. meaning.. my led will blink twice evry other second even without me talking into the mic,... when i touch the mic... it will have sound output... but rather noisy..

  8. mr audioguru...

    Bell (20-200 Hz) - Diaphragm (100-500 Hz) - Extended Range (20-1000 Hz)
    these are the ranges that a normal stethoscope can or should detect... can this circuit be likewise? wat changes needed to be done to the circuit to achieve this modes...?? wat is the frequency range of this current circuitry... hope u can reply me asap.. thanks....

  9. hi again..

    sorry to disturb u... if i wanna connect a speaker to the circuit.. how
    do i do it? will the led cont to light up when i turn the swith to off?
    its contant blinking when i switch it off.. till i unplugged the batt
    connection only it will slowly fade off...


  10. heyz.. audioguru....

    had been working on ur circuit.... i did use a function generator to input some signals.. the output was quite ok.. not much noises.. i cant hear anything using the mic though.. maybe i burned it while soldering... hehe..

    anywaes.. do u have the circuit diagram in .ckt format? i need to change it to pcb.. or better maybe straight the pcb diagram..?? =)

    dazza... ur box looks cool.. good job..


  11. heyz...

    im currently working on my final year project.... it wld be really helpful if anyone cld tell me which is the finalised circuit that i shld follow......something that will work... is it the stethoscope 2 that audioguru posted?

    and.. if i wld like to connect the entire circuit to the computer... which means i do not use a headphone but to play the sound straight through the com.. how do i go about it? wat jack do i need to use?


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