Search results

  1. audioguru2

    Are datasheets important?

    I think I got banned at least one time, then I changed my IP address and got back in. ;D It is too bad that the thread with a detailed discussion about the 500W inverter's problems got deleted. Did you notice that it uses two quad opamps instead of a single dual opamp? MP, Please make the...
  2. audioguru2

    0-30 Vdc Stabilized Power Supply

    It doesn't make any difference. They both have Q1 to quickly reduce the output voltage to zero when the power is turned off.
  3. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Hi Ante, Engineers at TI actually engineer many circuits and projects, correctly. I have a new topic in the Theory forum about the problems with the CD4047 oscillator's errors in our 500W inverter project.
  4. audioguru2

    transistors

    Hi Max, Electronic parts distributors sell thousands of different transistors. Each one has a part number and has certain specifications for max voltage, max current and max power (heating). There are also many other spec's for transistors. The manufacturers publish a datasheet for each...
  5. audioguru2

    MOSFET PINOUTS HELP

    Hi Raka, They don't show pinouts in the package details because pinouts are different for different transistors. The BC547 and the 2N3904 transistors are nearly identical and both have the same TO-92 package. But their pinouts are completely opposite. Some RF transistors in the TO-92 case have...
  6. audioguru2

    Are datasheets important?

    Our Low Cost 500W Inverter project uses a CD4047 oscillator IC which divides the oscillator frequency by 2 for a 50Hz output from the inverter. The project originally used a 100 ohm resistor and a 4.7uf capacitor for its 100Hz oscillator. Somebody (a God) changed the resistor's value to 1k. Is...
  7. audioguru2

    MOSFET PINOUTS HELP

    Why not look at the datasheet for the part to see which pin is which? You can get datasheets from Google, but I get most from www.datasheetarchive.com and from many other sites.
  8. audioguru2

    Two PCBs off of one power source

    Your pic appears to be a completely different circuit than the FRS schematic you posted. Where is its NJR2073 audio power amplifier IC?
  9. audioguru2

    Multi-Voltage Battery Pack

    Why does part of your circuit need a lower supply voltage than the other part? Most electronic circuits work fine with a higher supply voltage.
  10. audioguru2

    0-30 Vdc Stabilized Power Supply

    The 7812 doesn't have an on and off control. An LM317 voltage regulator could have its ADJ pin grounded by a comparator when you turn off the power which would quickly reduce the output voltage to about 1.3V.
  11. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Omni, This power supply project reduces its output voltage to zero very quickly with its transistor Q1 when its power is turned off, so that the output voltage doesn't rise when the opamps lose some of their supply voltage. You don't want the output voltage to rise because  then it might...
  12. audioguru2

    insect attach

    Hi Eplanet, Sorry, I don't speak Persian. Iran is on the other side of the world from me. I have never been near Iran. Is there an electronics website in Iran? Texas Instruments and other experts recommend a minimum value of 10k ohms for the oscillator resistor of the CD4047. Yours is 4.7k ohms...
  13. audioguru2

    white led

    3.6V in 11 ohms is a current of 327ma. If the forward voltage of your LED at 327mA is 3.48V then this current regulator is fine.
  14. audioguru2

    white led

    A 9V transformer will provide plenty of DC voltage for the LM317 current regulator to drive a single 350mA LED. The LM317 will overheat without a small heatsink.
  15. audioguru2

    Multi-Voltage Battery Pack

    Hi Amplificar, Welcome to our forum. ;D You don't need to switch batteries, just stepup the voltage of two or three cells to any voltage you want, like the circuit does in an LED flashlight. In Google, enter Silicon Chip Never Buy Another 9V Battery. Google will give you a link to Silicon Chip...
  16. audioguru2

    Electronic Stethoscope

    Yes, you understand the circuit. I guessed at the output level from the microphone. It might be 5mV peak or it might be 20mV peak. Each heart would probably have a different level.
  17. audioguru2

    Electronic Stethoscope

    The 741 cannot drive 16 ohm headphones, nor 1k, nor 3.9 ohms. It can drive 2.2k ohms in parallel with 19k resulting in a load of 2k ohms. This is how to connect negative feedback:
  18. audioguru2

    white led

    There is not enough voltage if the  LM317 is a weak one. If your mains voltage drops then the LED might dim more.
  19. audioguru2

    Two PCBs off of one power source

    Hi Bruce, The volume control in the FRS radio feeds its audio amp (the NJM2073 has a voltage gain of 100) which has an output for the speaker, or for the earphone and for your MC34119 mixer/amp.
  20. audioguru2

    white led

    Almost. The rectifier bridge reduces the voltage to 7.1V. Then the max output voltage of the LM317 will be about 4.6V and the 3.9 ohm resistor reduces the max voltage for the LED to only 3.35V. Doesn't the LED need 3.9V?
Top