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  1. Audioguru

    Help With Calculations

    Look again. The schematic shows R1 as 100 ohms but your calculation wrongly has it as 200 ohms.
  2. Audioguru

    Need help with this certain circuit (RC phase shift system)

    ALL electronic circuits need a supply bypass capacitor. Connect a 10uF to 100uF capacitor from +5V to ground. Your volume control is backwards, it must be a voltage divider FROM the input TO the output. The 3rd "R" has R1 and the input impedance of the transistor parallel to it which reduces...
  3. Audioguru

    Current limiting resistor power rating question

    When the light is focussed into a narrow beam then on-axis it is much brighter. An ordinary 100W household bulb is not focussed into a narrow beam so it is not as bright. You can look at a datasheet for a resistor to see its temperature at its power rating. Paper ignites at 232 degrees C and...
  4. Audioguru

    Current limiting resistor power rating question

    Nobody makes an LED with a voltage of 4.5V. An LED has a range of voltages and yours might be 3.5V and the current is much higher than if it has a voltage of 4.5V or 5.5V. 12V supply, 4.5V LED and 100 ohms produces a current of (12V - 4.5V)/100 ohms= 75mA. The power in the resistor is 75mA...
  5. Audioguru

    FS FlySky radio setup help

    Most of my RC models are made by Horizon Hobby in the USA. Their manuals are very simple and clear. One quad-copter is a cheap Chinese one and like you I do not understand its instructions.
  6. Audioguru

    Best connectors for Iron Man flying suit

    The inventor has such a strong accent that I could not understand what he was saying. I dream about flying like that without the jet packs.
  7. Audioguru

    FS FlySky radio setup help

    Since you have the quad-copter then you should also have a transmitter for it and its manual. Reviews on the web say the manual is hilarious because it is written in Chinglish and is hard to understand.
  8. Audioguru

    mosfet power supply issue

    You show a box instead of a Mosfet symbol. Your box has no part number but all Mosfets have a part number. Your box has 4 wires but all Mosfets have only 3 wires, the gate as the input, the source as the common and the drain as the output. Your box does not have these markings.
  9. Audioguru

    Need help with this certain circuit (RC phase shift system)

    Please describe "alternating sound". The output of the oscillator and the amplifier is AC that is "Alternating Current". If you want to increase and decrease the output level then use the potentiometer as a volume control between the output of the oscillator and the input of the amplifier. Your...
  10. Audioguru

    DIY power supply...no output

    The kit is a Chinese copy of an old Greek kit that is a project at www.electronics-lab.com. The project has many overloaded parts and cannot produce 30VDC at 3A. The overloaded parts fail soon then the project is dead. Even if the transformer does not produce more than 24VAC with no load then...
  11. Audioguru

    Need help with this certain circuit (RC phase shift system)

    The design of the 741 opamp is 49 years old and it will not do anything with a supply as low as 5V. Also its inputs are not biased correctly and it has no negative feedback. It cannot drive a speaker. Use an LM386 audio power amplifier instead. It can be powered from only 5V but then its output...
  12. Audioguru

    8 channel sinusoidal function generator

    Opamps cannot drive a load as low as 50 ohms to 15V p-p at 1MHz.
  13. Audioguru

    First amplifier build

    Its design is 50 years old. Where will you find its old parts? Why not make a modern amplifier?
  14. Audioguru

    8 channel sinusoidal function generator

    Who makes a piezo transducer that works as high as 1MHz and must produce 0.5W RMS? Why do you call 1MHz acoustic? It is far higher than ultrasonic and is smack in the middle of the AM radio broadcast band.
  15. Audioguru

    First post... question about small capacitor and DC motor

    Why not look at its datasheet that tells you all about it. Maximum supply voltage is 15V, every circuit shown in the datasheet has a 0.1uF capacitor supply bypass capacitor to smooth the supply voltage. Supply voltage regulation is not needed. The datasheet shows that its output current is too...
  16. Audioguru

    First post... question about small capacitor and DC motor

    I was wrong. A Cmos 555 timer has a very small supply current of about 200uA (0.2mA) all the time.
  17. Audioguru

    First post... question about small capacitor and DC motor

    Yes, a Cmos timer will begin timing when a momentary switch closes for a moment. The motor will run at full speed then turn off when the timing finishes. Here is a circuit with a single pushbutton that turns on the relay when the button is pushed then turns off the relay when the button is...
  18. Audioguru

    First post... question about small capacitor and DC motor

    The minimum supply voltage for an ordinary 555 (LM555 or NE555) is 4.5V that you do not have. The minimum voltage for a Cmos 555 timer IC (LMC555, TLC555 and ICM7555) is 1.5V. An ordinary 555 timer will drain the battery all the time but the Cmos one does not.
  19. Audioguru

    First post... question about small capacitor and DC motor

    The voltage on a charged capacitor drops quickly as it is discharged. Then the motor would slow down then stop. Maybe you want the motor to run at full speed then stop? Then you need a timer and electronic switch circuit. A Cmos 555 can be the timer and it can drive a transistor used as the switch.
  20. Audioguru

    Digital Filter Design Approach

    An ECG signal has DC baseline drift caused by muscles in the patient and mains hum interference picked up by the patient's body. Then most ECG circuits use the common-mode DC and AC interference signal produced by the instrumentation amplifier IC, invert it and feed it to the patient (usually to...
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