Search results

  1. audioguru2

    Power supply for amps

    Hi Francois, Speakers are inductive which causes them to have a high impedance at high frequencies. The RC networks at the amplifier outputs are "zobel networks" that are a low impedance at high frequencies to prevent the amplifiers from oscillating. An inductor and capacitors to make a passive...
  2. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Hi Morro, The peak voltage of a sine-wave is 1.414 times its RMS value. Its RMS value is the same as the peak voltage of a square-wave. So the peak voltage of a modified sine-wave inverter must be higher than if it is a square-wave inverter. The fully charged car battery is 13.8V and the...
  3. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Hi Morro, The IRF540 Mosfet is pretty old so has a fairly high on-resistance compared to newer Mosfets. Therefore they will get hot in a powerful inverter. The CD4047 is Cmos with a supply voltage rating up to 18V. It doesn't need a supply of only 5V like old TTL logic chips, it works fine from...
  4. audioguru2

    Audioguru FM Tx

    Maybe they are getting 10 times more power into a 50 ohm resistor than my circuit, but I get excellent range with just a half-wave long antenna wire. They tested all their changes, I didn't.
  5. audioguru2

    Power supply for amps

    The cicuit for the Velleman kit amp is simple and basic. The National amp IC is the best they can make. No wonder Velleman don't say what is its distortion at anywhere near its full output.
  6. audioguru2

    Resistor help

    Is the Maplin one the correct physical size? Replace the other one too if you are worried about it.
  7. audioguru2

    Audioguru FM Tx

    They built and modified the mod 3 version of my FM transmitter. The mod 4 version works much better and has the 5V regulator.
  8. audioguru2

    Resistor help

    Yes, R260 is 270 ohms, 1% tolerance.
  9. audioguru2

    Audioguru FM Tx

    Hi Sssaaa, They changed a lot of things in my circuit, starting with using 9V for the RF oscillator instead of the regulated 5V that I used. They measured 3V p-p at the output which I think is very low. Maybe they terminated the output with 50 ohms which results in a power of only 22.5mW. I...
  10. audioguru2

    Peak Inverse Voltage of a rectifier

    It is just the voltage rating of the rectifier. It doesn't affect how well it rectifies. A half-wave rectifier rectifies for half the amount of time as a full-wave rectifier. So the half-wave produces a lot of ripple voltage while its capacitor discharges. But the full-wave rectifier rectifies...
  11. audioguru2

    Audioguru FM Tx

    Hi AN, Welcome to our forum. ;D Which website is talking about my FM transmitter circuit? I would like to find out why my 5V regulator wasn't used to keep the oscillator frequency more stable and how the low power of only 10mW was calculated.
  12. audioguru2

    Power supply for amps

    Nice going, Francois. ;D How did you fix the noise problem?
  13. audioguru2

    pyrometer

    Did you use an infrared photodiode or phototransistor that are made for IR and are in a black package? What temperature change from from the ambient temperature do you want to measure? What distance? Please post the schematics that you tried.
  14. audioguru2

    Current-dropping current source! I don't get it! Please help!

    You should keep this dicussion in your original thread about a current source. A tiny change of only 0.1mA in a current of 52.2mA is a change of only 0.2%. The values of your resistors probably change more than that.
  15. audioguru2

    Peak Inverse Voltage of a rectifier

    Hi Shaiq, How much is the voltage of your mains? 230VAC? Then its peak voltage is 230V times the root of 2= 325V. If you rectify it then the minimum peak inverse voltage rating of the rectifier is 325V, and you would probably use one rated for 400V or 500V to allow for spikes. A voltage that is...
  16. audioguru2

    Low-pass Filter?

    Hi Hericlj, Good, you built the fixed circuit. The transformer doesn't have 0V terminals. Its primary winding has a center-tap that is connected to the fused and switched positive 12V, and it has two terminals for the collectors of each side's output transistors. The emitter resistors of the...
  17. audioguru2

    Resistor help

    You say that you have another amp the same. It is easy to troubleshoot a stereo amp if only one channel has a problem, because the other channel is the same and it works. The defective amp can have its voltages measured and compared to the good amp. Parts can be seen with their color bands...
  18. audioguru2

    Low-pass Filter?

    There are two 500W inverter schematics in the project. The original one has a shorted CD4047, its RC values are wrong, it doesn't have enough 2N3055 transistors and they are shorted.
  19. audioguru2

    Resistor help

    The resistor's value isn't r260. It is the 260th resistor on the schematic. Look at the other resistors, r258 isn't 258 ohms and r259 isn't 259 ohms. Look at the color bands on the r260 resistor on the good amp and get a replacement resistor the same.
  20. audioguru2

    Resistor help

    You need to fix the problem that caused the resistor to burn. Or the replacement resistor will also burn.
Top