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  1. audioguru2

    LOGIC GATES project

    Swap the LEDs. If one side is always dim then the circuit on that side has a problem. Maybe the circuit for the bright side has a problem instead. TTL and Cmos logic devices are completely different: 1) TTL operates from a 5V supply only. Ordinary Cmos operates with a supply from 3V to 15V or...
  2. audioguru2

    Need Help

    There are many duplicated threads. Each forum needs a moderator to delete the extra threads before there are replies to each of them.
  3. audioguru2

    pramplifier circuit

    C2 is part of the opamp's inverting input circuit. It blocks DC and allows the opamp to be a DC follower with a gain of only 1 at DC. If C2 is shorted then the gain of the opamp would force its output to the positive supply. With C2 in the circuit, the DC output voltage is at half the supply...
  4. audioguru2

    LOGIC GATES project

    It is an experiment in Chapter 7, Volume VI at www.allaboutcircuits.com .
  5. audioguru2

    14 3v LED's powered by 12-15vdc

    The simplest way to connect 14 of your LEDs is to connect a 470 ohm resistor in series with each one. Then the combinations of the LEDs with resistors connect to the electrical. You mentioned series connections. Three LEDs can be wired in series then in series with a different resistor. The...
  6. audioguru2

    14 3v LED's powered by 12-15vdc

    Hi Alaskan, Welcome to our forum. ;D If your LEDs are a normal size then their max current rating is probably 30mA. When the vehicle's electrical voltage is 15V then the current in each LED is limited to 25.5mA by its 470 ohm resistor so should be safe without burning out. The 470 ohm resistors...
  7. audioguru2

    Bass Box

    The datasheet for the TDA1516 doesn't say much about its bootstrap pins but you are not using them so they should be connected to the positive supply Vp as you show. The datasheet says what to do with pin 12 when bootstrapping is used but doesn't say what to do without bootstrapping. This amp...
  8. audioguru2

    common-mode??

    Hi Mudhall, Welcome to our forum. ;D Common-mode signals to an opamp are signals that are the same at both inputs. The range of common mode signals for most opamps is within a few volts from each supply voltage. A few opamps like the LM324 and LM358 have inputs with a common mode voltage range...
  9. audioguru2

    amplifier hum

    A polyester cap is a mylar cap or is also known as a "green cap" but I have seen oriental "brown caps" that are the same.
  10. audioguru2

    LOGIC GATES project

    You can't do much without the datasheets or a good textbook like "The Cmos Cookbook". They show the spec's, pins and the logic functions of the ICs.
  11. audioguru2

    0-30 Vdc Stabilized Power Supply

    Most digital meters have a 200mV full-scale and an extremely low input current. Most moving coil meters are also very sensitive. If resistors can't be removed from your meter to make it more sensitive then a complicated amplifier is needed for it.
  12. audioguru2

    Lowpass filter for subwoofer

    The circuit doesn't use a single TL071 opamp. It uses a dual opamp like a TL072. The dual jrc4559 will also work fine in the circuit.
  13. audioguru2

    LOGIC GATES project

    The capacitor is the supply bypass cap. It keeps the supply at an unfluctuationg low impedance when the internal resistance of the battery rises as it runs down. The circuit might oscillate without it when the battery is a little used. The transistor drives the LED with 10.6mA (Ohm's Law). The...
  14. audioguru2

    200W Audio amp by kemo kits

  15. audioguru2

    0-30 Vdc Stabilized Power Supply

    C10 is not needed. It was an extra mistake on the revised parts list.
  16. audioguru2

    about mixer

    It doesn't have an LED. It has three 1N914 ordinary diodes to avoid crossover distortion. An audio mixer adds together sound signals from more than one source. Each input has its own level control to allow a proper blend. An audio equalizer adjusts the levels of different audio frequencies.
  17. audioguru2

    Bass Box

    The signal causes a current in the input resistors. The inverting amplifier with the virtual ground input creates the same amount of current current to flow in its negative feedback resistor which causes amplification of the signal.
  18. audioguru2

    Bass Box

  19. audioguru2

    Electronic Stethoscope

    I guess Digikey don't sell many jFETs. Newarkinone sell the 2N3819 in single quantities for only $.166US today.
  20. audioguru2

    Electronic Stethoscope

    A volume cotrol rated at 1/2W might be turned down only 10%. Then 1/10th of it would have the output current in it which could easily burn it. A Cmos transmission gate is an electronic switch. There are many different types. You could use that FET audio mixer if you want.
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