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  1. Audioguru

    Bluetooth Mic

    The cost of hearing aid products does not matter here in Canada because money grows on trees and you just need to pick it off the tree or from the ground under each tree. I phoned my audiologist and they are thinking about how much profit they can make if I buy a Roger Pen Bluetooth wireless mic...
  2. Audioguru

    Bluetooth Mic

    The Swiss company Phonak that make my hearing aids make a Roger Pen that is a Bluetooth wireless mic.
  3. Audioguru

    Gain of operational amplifier...

    You posted a very fuzzy schematic saved as a Jpeg file type instead of a very clear PNG so I cannot read the opamp part number. The datasheet of every opamp shows a graph of its gain from DC to a high frequency where its gain is less than 1. When you short R2 then you are removing all negative...
  4. Audioguru

    Pre-Scaling a squarewave. Output weird.

    This is not an ordinary Cmos low power CD4040, instead it is high speed , high power HC4040 Cmos. Its datasheet shows a maximum allowed output of 25mA and no more than 50mA for the entire IC. But an HC Cmos IC can produce 45mA into an LED per output without a current-limiting resistor and you...
  5. Audioguru

    Bluetooth Mic

    If the microphone can hear the speaker then you will have acoustical feedback howling as the sounds go around and around and around and around and around ....
  6. Audioguru

    Where can i buy the mosfets i need for my project?

    Your Mosfets are shown backwards as source followers instead of as switches. The source of the P-channel Mosfet should connect to the positive supply and the source of the N-channel Mosfet should connect to 0V. It would be obvious that the body diodes in each Mosfet are shorting the 9V battery...
  7. Audioguru

    Current passing for regulator IC's

    Transistors and darlingtons have a wide range of base-emitter voltage that also changes as they get warm. The datasheets show a maximum voltage for some of them and a typical voltage for others but the range is so wide that you will need to test the one you use and calculate a resistor for it...
  8. Audioguru

    Current passing for regulator IC's

    The transistor also needs base current. With a collector current of 2A then the minimum current gain of a TIP42 is 25 then its base current is 2000/25= 80mA which will flow through the regulator in addition to the 50mA in the resistor.Then the total current in the regulator is more than the...
  9. Audioguru

    Current passing for regulator IC's

    The base-emitter voltage turns on the transistor. It begins to turn on when the base voltage is about 0.6V less than its emitter voltage and is about 1.8V when the collector to emitter current is typically 10A. Then for a base-emitter voltage of 0.6V the current in the transistor is about 50mA...
  10. Audioguru

    HELP!!!!!! Question About Powering LEDs

    You forgot to post a link to the LED strips you have. Ones shown in Google are powered from 12VDC and use 3.7W per foot. Yours might use 3.7W x 70 feet= 259W so they must be wired in separate groups of maybe 30W per group so that the wires do not burn up. 259W/12V= 21.6A that your power supply...
  11. Audioguru

    Ultrasonic sonar

    The transmitter has a low impedance for good power output then the transducer will not resonate. The receiver is damped by the water so it also might not resonate. A capacitor does not electrically resonate, it needs an additional inductor. A piezo is a capacitance.
  12. Audioguru

    Current passing for regulator IC's

    The resistor does not limit the current, instead it senses the current then turns on the transistor. You want the transistor to turn on with a base-emitter voltage across the resistor of 0.6V and a current of 80mA so the resistor value is 0.6V/80mA= 7.5 ohms. But why not 50mA then the resistor...
  13. Audioguru

    Ultrasonic sonar

    How much voltage is produced by the piezo when it picks up a reflection? 2mV? But how much voltage do the diodes need to conduct a little? 500mV? Then do the diodes block the signal even if it resonates? No.
  14. Audioguru

    Ultrasonic sonar

    The datasheet for your 40kHz piezo transducer will show its resonance. It is not an inductor needing a capacitor, its resonance is mechanical.
  15. Audioguru

    PWM controlled DC motor using 2n3055: Is it okay? How can be inproved? + Proteus file

    You do not know about PWM, did not look at the datasheets of the opamp and transistor, and you did not do the math. Also you should never call a 2N3055 a 2N3305. The maximium current the motor uses is 10A at 12V. But the 741 opamp design is 50 years old and has a maximum output current of only...
  16. Audioguru

    Peak detector to A/D of PIC

    You have 10k and 20k effectively in parallel at 6.66k reducing the 7V input to 2.33V. The diode drops 0.6V to 1.733V. The capacitor charges in one time period to 1.16V in the time of 6.66k x 220nF= 1.5ms and almost the peak in 7.3ms. The 43k load and PIC input resistance also reduce the voltages.
  17. Audioguru

    Current passing for regulator IC's

    An emitter follower ruins the excellent voltage regulation of an IC regulator IC because its base-emitter voltage changes when the current changes. A PNP pass transistor added to a positive IC voltage regulator is not an emitter follower and produces excellent voltage regulation because it is...
  18. Audioguru

    Ultrasonic sonar

    The diodes prevent the high transmit voltage from the transformer from destroying the receive opamp's inputs. The diodes do not do anything when receiving a low level echo.
  19. Audioguru

    Ultrasonic sonar

    I have not seen the spec's for your 40kHz piezo but the ones I have seen are a high impedance with a minimum load of about 50k ohms. Your parallel R5 and R6 in series with R4 create a load of only 1.5k which will be like a short across the piezo and reduce its output to almost zero. I would make...
  20. Audioguru

    DIY voltage Regulator

    Its output voltage is not regulated properly because it is simply an emitter follower with losses attached to a zener diode that also has losses. The zener diode is 13V only when its current is 5mA but the 10k resistor value is too high to supply the transistor and the zener diode properly when...
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