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  1. Audioguru

    I'm Back- sort of

    We do not see your potentiometers so we do not know if the knob points towards you or points away from you. Simply pick a pair of my sketches and paste them into Microsoft Paint program. Use an ohm-meter to determine that the volume control slider (middle prong) connected to ground when the...
  2. Audioguru

    I'm Back- sort of

    I believe that the potentiometers are shown wrongly. The tone control cuts highs and should be clockwise for maximum highs. The volume control should be clockwise for most loudness.
  3. Audioguru

    Adding Frequency Scanning to any AM/FM/SW Radio

    Where will you find a radio that has voltage tuning? Where inside the radio will you connect the voltage sweeping circuit? Why do you or anybody want a radio that sweeps all stations in a radio band?
  4. Audioguru

    Adding Frequency Scanning to any AM/FM/SW Radio

    Very few radios are tuned with the variable voltage from that circuit. Why do you want to sweep the tuned frequencies anyway? The sweep circuit does not not "scan then stop at the next station" that a few radios have.
  5. Audioguru

    I'm Back- sort of

    Most Fuzz or Overdrive distortion is the amplifier clipping or the diodes clipping the amplitude of the signal. Most clipping is symmetrical so the top and bottom of the waveform are equally limited at the maximum amplitude. Smooth signals end up as squarewaves. Symmetrical clipping produces odd...
  6. Audioguru

    Water level meter

    Maybe the water level sensor is a 190 ohms potentiometer with a float that moves its slider up when the water level is high and moves the slider down when the water level is low? We do not know of the potentiometer can survive 12V across it.
  7. Audioguru

    I'm Back- sort of

    The circuit you found id completely useless and is wrong with a obsolete TDA2030 power amplifier that has a minimum of 12V for its supply so it will not work with a 9V battery that drops to 6V and it will not work with an old 741 opamp with different pins numbers since the circuit is completely...
  8. Audioguru

    555 output question

    The maximum allowed output current of an ordinary old 555 is 200mA that will quickly burn out an ordinary LED that has a maximum allowed continuous current of 30mA. Therefore the LED needs a series current-limiting resistor. The 555 might be a modern Cmos LMC555, TLC555 or ICM7555 that has much...
  9. Audioguru

    Illuminated Switch Question.

    An LED is a diode then a reverse voltage will not cause it to light. Why do you think there is a reverse voltage? Which LED is slightly lit? The one in the switch or the one you added somewhere? Can you calculate a new resistor for your 5V supply and replace the existing resistor? Here is the...
  10. Audioguru

    Old module does not work

    I bought an '89 Sunbird Turbo for my wife's first car and she loved it. Then our daughter got it.
  11. Audioguru

    Oscilloscope Probe at Audio Amplifier Output Causes HF Oscillation

    It is class-A so its heating power is more than its feeble output power even when it plays very low levels. It oscillates because it is missing a frequency compensation capacitor.
  12. Audioguru

    make this VU meter more sensitive, please

    The LM3914 is a linear voltmeter indicator IC not used for audio. The LM3915 3dB per steps audio level indicator IC is obsolete. I guess I bought the last few that were made. The LM3916 many levels audio IC is made by a copy-cat company and costs a fortune.
  13. Audioguru

    Home made battery packs

    You are assembling 8 AA cells in series/parallel making one fairly long lasting 3.6V to 6V battery. The total battery has only one negative and only one positive for one barrel connector.
  14. Audioguru

    Home made battery packs

    An AA alkaline battery cell is 0.9V to 1.5V. A bunch of battery cells in parallel still produce only 0.9V to 1.5V. Your Arduino needs at least 3.0V. So you need 4 battery cells in series to produce at least 3.6V or you can use 3 cells in series if you let the Arduino stop working when they...
  15. Audioguru

    How to limit solar charger current

    Parts that limit the current are shown on the charger schematic that you did not post.
  16. Audioguru

    Energy storage - alternatives to batteries

    Of course an explosion or fire will be a problem because lithium is a very active element. A charger must be properly designed and a low voltage cutoff circuit must be used. An over-current circuit must work when it is needed.
  17. Audioguru

    Energy storage - alternatives to batteries

    Ate you aware that a Lithium battery can explode and/or catch on fire if it is charged or discharged wrongly? If it is discharged to a voltage too low it is ruined and might catch on fire if a normal charge is attempted.
  18. Audioguru

    My life was a lie

    What is "before the load"? If an NPN transistor is a switch then the load is between its collector and the positive supply. If your load is between the emitter and ground then it is an "emitter-follower" and its emitter is about 0.7V less than its base voltage. The datasheet says how much is...
  19. Audioguru

    My life was a lie

    I guess you never looked at the datasheet of any transistor that says for saturated switch, the base current must be 1/10th of the collector current even when the hFE is very high. You mentioned a 0.7V loss then maybe your load was at the emitter instead of at the collector. I guess you never...
  20. Audioguru

    Energy storage - alternatives to batteries

    My local hobby store has many radio controlled model cars, trucks, boats, airplanes, jets, helicopters and drones. Most are powered with Li-PO batteries. The hobby store sells many batteries and chargers for them. My Li-PO batteries last for about 600 times or 3 to 4 years. I store them at 88%...
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