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  1. Audioguru

    Low pass filter

    I do not want a PM, please ask questions in the forum so anybody can answer them.
  2. Audioguru

    Low pass filter

    Look at a graph in Google of the frequency response of a simple single-order RC lowpass filter. It begins dropping at 1/5th of the -3dB cutoff frequency.
  3. Audioguru

    Bypassing TV's internal speakers to home-made aux input

    Since you do not use normal shielded audio cables that everybody else use then your wires are "antennas for interference pickup" which guarantee hum pickup, especially when the TV is turned off. I already explained that "When the TV is turned on it has a very low output impedance that shorts out...
  4. Audioguru

    Low pass filter

    You forgot to say any details about the lowpass filter. A simple single order RC? Then it cuts the harmonics gradually. If its cutoff frequency is 3.5kHz then it noticeably cuts 3.5k/5= 700Hz and higher.
  5. Audioguru

    Bypassing TV's internal speakers to home-made aux input

    I think the hum is caused by the wires between the TV and the input of your PC amplified speaker system are not shielded audio cables where the shields block hum pickup from all around you. When the TV is turned on it has a very low output impedance that shorts out most but not all of the hum...
  6. Audioguru

    Tone for thought..

    The 2V calibration squarewave is used to setup a 'scope so that its voltage, frequency and frequency response are accurate then it is not used anymore when looking at signal waveforms. Usually a fixed frequency is fed to the input of the 'scope and the horizontal is set for a linear sweep. The...
  7. Audioguru

    Wiring Batteries?

    There are lots of different kinds of batteries and you did not say which type. Car battery, AA or AAA alkaline cylindrical cells, button cells, Lithium-Ion cells or Li-Po cells. Most fit in a battery holder.
  8. Audioguru

    Beginner circuit problem

    The LED needs a current-limiting resistor in series with it. Its typical current is 20mA and a red LED is about 2V so the resistor should be (9V - 2V - 0.2V)/20mA= 340 ohms, use 330 ohms. The 555 will be cooler if the LED and its resistor connects to the +9V, not ground. What is 3.3mF...
  9. Audioguru

    I want to make clear sound of the woofer speaker.

    The amplifier that drives the speaker must have low distortion to make clear sounds. Your capacitor is not an amplifier. Please attach the schematic of the amplifier. What is the diameter of the woofer speaker and what impedance and power rating does it have?
  10. Audioguru

    Noob question about my resistor problem

    Who said the LEDs are 3.4V? They are diodes, not simple incandescent light bulbs so the voltage of each one is different. When you connect them in parallel then only the one with the lowest voltage will light very brightly with the 60mA and burn out very quickly, followed by the next one burning...
  11. Audioguru

    Who knows how to test N-Ch. MOFETS with Multimeter? Please HELP!

    On Ohms, my fluke multimeter can make a germanium and a Schotky diode conduct but not a silicon diode nor transistor junction conduct. On diode test it has enough voltage to faintly light a 1.8V red LED but not a 3V blue nor white LED. I haven't tried testing a Mosfet because its threshold...
  12. Audioguru

    FM Pulse Counting Circuit Sounds Bad

    A normal superhet FM radio has a tuned RF amplifier with gain control, an IF amplifier to give it good selectivity and a normal FM detector. It works extremely well.
  13. Audioguru

    Who knows how to test N-Ch. MOFETS with Multimeter? Please HELP!

    A Mosfet needs a few volts or more gate to source to turn on. But a digital multimeter measuring Ohms gives only 0.2V which is way too low. An old analog multimeter might use a 9V battery to test resistance. Of course the test with the 12V shows that the Mosfet is normal.
  14. Audioguru

    FM Pulse Counting Circuit Sounds Bad

    C16 and C17 are only 150pF which is almost nothing, maybe you wrongly used 150nF? Together with R7 and R8 they cut frequencies above 226kHz which is far higher than audio frequencies. R9 and C15 produce a little less de-emphasis used in the UK so the response will be a little boosted at high...
  15. Audioguru

    LED setup help needed.

    It sounds like school homework. We do not know if he was supposed to learn about flip flops, Cmos counters or microcontrollers. Duke37, a CD4017 lights only one LED at a time. He wants 2, 3... up to 7 LEDs to light up at the same time.
  16. Audioguru

    Alguien me podría ayudar...no se escucha el audio lo puse en opción DAD pero no sale el sonido

    From Google Translate: Someone to help me because at the time of playing is not heard I do not know what is due ... You must tell us what the sound signal comes from and what amplifier is used to play in a speaker.
  17. Audioguru

    Amplification to a constant Vpp

    Then your ranging sonar does not care if the signal is a sinewave or is clipped into a squarewave. So amplitude does not matter unless it is too small and needs more amplification.
  18. Audioguru

    Amplification to a constant Vpp

    The "frequency modulated sinusoidal input" to the mic is called a warble tone, or music with "vibrato". What is the signal used for?
  19. Audioguru

    Pnp bjt

    If the PNP is turned on then its collector cannot go much higher than its emitter, then the base voltage will be lower and will keep the transistor turned on. If the transistor is turned off then the collector can go higher than the emitter and base, then if the NPN tries to turn on the PNP it...
  20. Audioguru

    Easiest/cheapest way to prevent a capacitor from over charging??

    A 2.7V zener diode is available in many current ratings. Its voltage has a 5% tolerance so it is from 2.565V to 2.835V at its rated current at room temperature. Its voltage could be 3V or more when its current is high. So you need to know the current from the solar panel into the zener diode at...
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