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  1. Audioguru

    Speakers clipping w/ TDA7492P

    A 3s 18650 battery is 12.6V when fully charged. The datasheet for the TDA7492 amplifier shows a graph of maximum output vs supply voltage. The lowest supply voltage shown is 15V when the power is 23W at horrible 10% distortion or 19W at 1% distortion that can still be heard into 4 ohms. A 5s...
  2. Audioguru

    Tapco S5 speaker replacement

    Doesn't the speaker manufacturer have replacement parts for it?
  3. Audioguru

    Active Filter Design

    You have a professor and are studying active filters so I assumed you were taught about decibels. Please ask your professor to teach about decibels.
  4. Audioguru

    Help with modification of radio Sony ICF-SW35

    I asked about why do you want a stereo indicator because the radio is mono with "PLL Synthesized Digital Tuning". Its chip has an FM stereo demodulator so maybe the headphones produce stereo. The radio is old so I could not find an owners manual. You do not tune in a station on this radio...
  5. Audioguru

    NP's of a Schematic

    Like most semiconductor devices, a diode has a part number. The datasheet for the part number has all the specifications and even has graphs.
  6. Audioguru

    Active Filter Design

    You should use a modern opamp that works at all audio frequencies. The lousy old 741 opamp was introduced 49 years ago, but not for audio (maybe AM radio sound quality?). Your lowpass filter is simple so it does not block frequencies, instead it reduces frequencies. If the cutoff is at 10kHz...
  7. Audioguru

    Help with modification of radio Sony ICF-SW35

    Why do you want a stereo indicator? Here in Canada FM radio stations are always in stereo and have been for many years.
  8. Audioguru

    Tapco S5 speaker replacement

    It is probably the amplifier that has failed, not the speaker.
  9. Audioguru

    Mobile charger to charge LiIon batteries, Usng Voltage Divider to drop voltage

    I cheat and charge two basic (no protection circuits) 18650 Lithium ion cells in series without a charger circuit and without a balanced charger in my portable little vacuum cleaner. My charger uses an LM317 voltage regulator set to 8.40V and its wall wart limits the charging current. I...
  10. Audioguru

    Can you check over this Circuit?

    The schematic says "electroschematics" which is a website in India. Most of its projects are designed by Mr.Kumar and some use that old siren IC but this circuit with its very old parts is not there anymore. Where did you find it? It will be simple to fix but then it will be triggered by any...
  11. Audioguru

    Why are my LTSPICE results so different from the 1N4148 datasheet and real life?

    Is 25 degrees C the temp of the chip or the temp of the ambient air? But we do not want the forward voltage of your diode because it is different for most 1N4148 diodes.They cannot all be made exactly the same, they have a range of forward voltage.
  12. Audioguru

    Mobile charger to charge LiIon batteries, Usng Voltage Divider to drop voltage

    The "mobile phone charger" is not a charging circuit. It is simply the power supply for the charging circuit that is inside the phone. You should use a lithium-ion charging IC in between the power supply and the battery.
  13. Audioguru

    Why are my LTSPICE results so different from the 1N4148 datasheet and real life?

    Why do you need the sim to show one voltage/current that you cannot buy? You get whatever they have because they cannot be made to all be the same. Are you trying to match a diode to the base-emitter of a transistor or to another diode? You can't unless you buy many, test them all and sort them...
  14. Audioguru

    How fragile are diodes? Can you screw them up soldering them?

    A cheap soldering iron has no control of its temperature. It gets hotter and hotter until it damages parts when they are soldered. If the solder has good flux in it then the high temperature burns it away then each solder joint takes longer time. Cheap plumber's solder needs a high temperature...
  15. Audioguru

    Step down transformers

    The battery in my car can produce 400A when cranking the starter motor and cold engine and its very thick oil in winter. Then the power from the battery is 12V x 400A= 4800W. But the clock in the car uses the same 12V battery and if it used 4800W then it would be white-hot and the battery will...
  16. Audioguru

    Step down transformers

    Load the transformer so it is producing 6VAC at 500mA into a 12 ohms resistor. Let it heat up for about 1 hour then feel its temperature. If it is very hot and smoking then it is using 20VA or more. If it is barely warm then it is using 3.3VA and its heating is 0.3W. Most transformers are very...
  17. Audioguru

    Step down transformers

    What is the question? The little 6V center-tapped transformer can provide a maximum continuous output of 6VAC at 500mA. Its secondary power output is 6V x 0.5A= 3VA. Its primary power input will be about 3.3VA.
  18. Audioguru

    A radio from 1920 goes to 2017 !

    Cheap things have poor quality, poor performance and do not last long.
  19. Audioguru

    Suggestions for a mobile power source for a guitar amp? Car battery, etc?

    A 19W amplifier will need more volts than just 12VDC. A single-ended amplifier needs a power supply of at least 39VDC to produce 19W into an 8 ohm speaker. Maybe the amplifier is bridged then needs about 21VDC. maybe the speaker is 4 ohms then the current is higher so the voltage can be less...
  20. Audioguru

    Better understanding of portable lithium battery pack

    Doesn't the battery pack have a user manual that shows you where its outputs are? It has an AC adapter that feeds its battery charger. It does not have an AC output but has USB and a few adjustable voltage outputs. The white material is some "goop" that holds parts down so they don't break...
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