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  1. audioguru2

    Low-pass Filter?

    Using a Clairtronic 13020 100VA transformer, the inverter will power up to an 80W load. Using a Clairtronic 13030 150VA transformer, the inverter will power up to a 120W load.
  2. audioguru2

    PSU Design for car audio amplifiers using UC2577-ADJ

    You can properly bias and capacitor-couple the load on any opamp or power amplifier. For a high power amplifier, the single supply voltage must be very high.
  3. audioguru2

    motor driver L298 help

    The L293 and L298 are just high current electronic switches. You need to drive them with a PWM circuit for speed control. PWM is Pulse-Width-Modulation and it pulses the the electronic switches at a high frequency. Wide pulses make full power and narrow pulses make low power. The PWM circuit...
  4. audioguru2

    PSU Design for car audio amplifiers using UC2577-ADJ

    I said that you should use a DC to AC inverter, not an inverting amplifier. An inverting amplifier with a negative output needs a negative supply that you don't have!
  5. audioguru2

    Low-pass Filter?

    The inverter doesn't need 8 output transistors for only an 80W load (100VA transformer). 4 output transistors will be fine, 2 on each side. It also doesn't need the 2N3055 driver transistors since the 2SC1061 transistors can directly drive the output transistors. The fuse will be 10A. A...
  6. audioguru2

    Help with Timer IC

    It has a lot more than that! Two voltage comparators, a flip-flop and a high-current output stage. Its schematic shows 28 transistors and 12 resistors but it could have more.
  7. audioguru2

    Low-pass Filter?

    Sorry. I looked at Jaycar but their search engine is stupid. Maybe they don't have a 600VA transformer that is powerful enough. I could spend days asking for a 500VA one, then a 400VA one etc. The 500W square-wave inverter needs a 600VA 10V-0-10V also called 20V center-tapped, or 12V-0-12V also...
  8. audioguru2

    PSU Design for car audio amplifiers using UC2577-ADJ

    You don't want a converter. You want the power supply circuit to be a high frequency inverter with a transformer, not just a coil. Then a full-wave rectifier at its output provides positive and negative high voltages.
  9. audioguru2

    Electronic Stethoscope

    Your 741 opamp at the output doesn't have any negative feedback and therefore has a voltage gain of about 200,000. The LM386 that it is supposed to be has built-in negative feedback and therefore has a voltage gain of only 20. The gain of the 741 opamp is 10,000 times too high, sure it will...
  10. audioguru2

    Low-pass Filter?

    A 500W inverter uses 600W from 12V which is a current of 50A. The 4 output transistors on each side divide the 50A into 12.5A each. A 2N3055 has a minimum current gain of only 5 at a collector current of 10A and isn't even spec'd at 12.5A but then its minimum gain is probably only 4. Therefore...
  11. audioguru2

    Low-pass Filter?

    The buffers in a CD4050 will drive transistors as well as opamps, but is in a 16 pins case. Dual opamps cost about the same and are in an 8 pins case.
  12. audioguru2

    DIY WBO2

    You attached a very fuzzy bitmap schematic here, but posted a very clear PNG file type over there. Why not attach the very clear PNG to your reply here? Its thumbnail will be resized, but when we click on it then it will be big and clear. Your car has a +12V battery. In addition to it, your...
  13. audioguru2

    Amplyfier for MP3 player.

    The power from an amplifier goes to the attached speakers, not backwards into the MP3 player. If $24.00 worth of Nickel-Metal Hydride rechargable battery cells is too expensive then you can replace $8.00 worth of alkaline cells a couple of times a day. You could use a few hundred dollars worth...
  14. audioguru2

    Amplyfier for MP3 player.

    Hi Krixer, Welcome to our forum. ;D Little 9V alkaline or rechargable batteries hardly have any power. Two can power a stereo amplifier with 2 Watts per channel for only 2 hours and the power would keep dropping as the batteries run down. 8 AA alkaline or rechargable cells will power a stereo...
  15. audioguru2

    Low-pass Filter?

    A Jaycar 2156 transformer is a dinky little thing with a 30VA max rating. It has a 240V winding and a single multi-tapped low voltage winding. 30VA is far too low for an inverter. 100VA is about the minimum. That is the max power of its load. The low voltage winding is not center-tapped nor is...
  16. audioguru2

    PSU Design for car audio amplifiers using UC2577-ADJ

    Hi Faizan, This is a positive stepup converter. It has the same ground as another one. So it cannot be used serially to get a negative voltage unless the two circuits are completely separate. In two different cars?? One car would have a positive supply and the other car would have a negative...
  17. audioguru2

    3 Minute Timer

  18. audioguru2

    Led display Digital Voltmeter question

    To make a 0V reference voltage for the circuit. It is supposed to have a positive 5V supply and a negative 5V supply.
  19. audioguru2

    Low-pass Filter?

    Please attach the datasheet for your transformer. Maybe its "0V" terminals are already connected together as a center-tap. Maybe the "0V" terminals are connected together and are connected to the transformer's frame. You could easily measure with a multimeter how the transformer is made: 1)...
  20. audioguru2

    7.6MHz Crystals

    Only a few parts per million. Quartz crystals have an extremely accurate frequency. Just buy or order the exact frequency you want.
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