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  1. audioguru2

    DC to AC

    It is an ordinary Cmos logic IC. Their supply voltage range is from 3V to 18V and their output voltage goes to the supply voltage if the load current is very low. With a 13.8V supply, the max output current is about 8mA. A UPS charges its batteries when power is present then automatically...
  2. audioguru2

    current/gauge increase

    12 gauge copper wire can carry a lot more than only 3A.
  3. audioguru2

    DC to AC

    Aren't we talking about an power inverter circuit, not just any oscillator? Their waveform isn't a perfect square-wave. It is "squared" but is not 50-50 duty-cycle. A 4047 oscillator makes a "squared-wave" signal like those others then divides it by 2 with a flip-flop so its outputs are exactly...
  4. audioguru2

    indulis or Audioguru?

    We are both correct about our guesses why H_Man's Mosfet didn't make high voltage spikes with his inductor. He tried a Mosfet with much less capacitance and it is fine. ;D
  5. audioguru2

    DC to AC

    A 555 astable oscillator makes nearly a square-wave. With more resistors and a diode then the output can be adjusted to be a perfect square-wave. The 4047 needs only a single resistor and a single capacitor to make a perfect square-wave and its opposite phase. There are lots of circuits that...
  6. audioguru2

    A simple transistor switch for an LED light.

    Yeah, for lighting a 2V LED from a 9V battery, a high gain transistor will give 20mA and a low gain transistor will give a 4V loss and 8.6mA but the LED will still give some light. If you use the correct value of base resistor for a transistor to saturate then a high gain transistor and a low...
  7. audioguru2

    key finder

    Our Keys Finder project is here: http://www.electronics-lab.com/projects/misc/002/index.html It has a detailed circuit description in its text. What don't you understand? "What is a fizzle??" I think it is a whistle.
  8. audioguru2

    DC to AC

    The 555 doesn't make AC, it makes pulsing DC. A coupling capacitor can feed an ordinary transformer winding from a complementary push-pull output circuit.
  9. audioguru2

    DC to AC

    No, but the transistors would melt if they were fed a sine-wave anyway. The transistors switch fully on (low voltage so low heating) and fully off (no current so no heating) with a square-wave. A linear sine-wave would keep them conducting near halfway all the time and make them extremely hot...
  10. audioguru2

    DC to AC

    Our simple 500W inverter project has a square-wave output that has the same effective power as a sine-wave. http://www.electronics-lab.com/projects/power/033/index.html It uses an IC to make two 50Hz signals, one is the opposite phase of the other. Then the circuit uses a couple of opamps and...
  11. audioguru2

    Amplyfier for MP3 player.

    You built and like our "22W" amplifier project? Good. Speakers with a tweeter for the high frequencies and a woofer for the low frequencies need "a crossover network" to keep the low frequencies from destroying the delicate tweeter and to keep the high frequencies away from the woofer. Speaker...
  12. audioguru2

    need help with electronics coursework!

    Have you thought about these simple steps: 1) Select a temperature sensor IC or make your own with a thermistor and an opamp. 2) Make an audio oscillator/speaker driver from a 555 IC and a couple of transistors. 3) Make the 1st circuit turn on the 2nd circuit.
  13. audioguru2

    Making a 0-28VDC@0-3A Power Supply using linear regulators (LM350)

    The datasheet specs the TO-220 case can dissipate a max of 25W and the TO-3 case can dissipate a max of 50W with a perfect heatsink. Then it will need a 27V minimum input, and if the voltage is set low like 2V to 5V, then its max current will be reduced by its protective current limit to...
  14. audioguru2

    Testing of IR LED...

    What do you want to test about an IR LED? Its IR power output? Its beam width? Just shine it at the camera in a cell phone, digi-camera or video camera. Then you can see what it is doing.
  15. audioguru2

    Making a 0-28VDC@0-3A Power Supply using linear regulators (LM350)

    Only sometimes, read the details in the datasheet. 5A output current if it has between 3V and 10V across it. With more than 10V across it, it also reduces its max current to protect itself. It doesn't have a guaranteed minimum output current at higher voltages like the LM317 and LM350, but is...
  16. audioguru2

    Making a 0-28VDC@0-3A Power Supply using linear regulators (LM350)

    Hi Niksun, Look carefully at the datasheet for the LM350: 1) With more than 10V across it, it reduces its max current to protect itself. With 30V across it then its output current minimum is only 250mA, 1A is typical. Look at the Current Limit curve. The LM317 and LM338 operate similarly. 2) It...
  17. audioguru2

    audio jack input selector

    A 2-pole switch and some jacks in a little box would be simple. The parts would need to come from a real electronic parts distributor. You can copy the circuit of the things sold that detect the phone's sound then automatically mute the radio, but it is complicated for a nooby.
  18. audioguru2

    Digital Audio Broadcasting (DAB)

    Hi Paris, Go to www.google,com where they have a lot of information about DAB and just about everything.
  19. audioguru2

    Convert 0-30V 3A PSU to 5A or more

    Hi Herman, Sure the old 2N3055 is in the museum. This entire project is an old design, but it works well when its parts are corrected. 2N3055 transistors are cheap, Mosfets are expensive. This modified project has a max output current of only 5A, so why use a Mosfet rated at 33A? The output...
  20. audioguru2

    50Hz when you touch Oscilloscope probe

    Your body isn't tuned. It has a large surface area, is conductive (less resistance than the input of a 'scope), is insulated from ground and therefore picks up any signals that are there. A TV station is far away so a TV tuner needs good sensitivity by amplifying the signal. Hundreds of volts...
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