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  1. audioguru2

    Evaluating total energy usage from just DC voltage and current

    What do you have that draws 9500W? An electric locomotive? The heater for an olympic swimming pool?
  2. audioguru2

    LM338 Power Suply Current Regulator

    It looks like you did not read the datasheet for the LM338: 1) It shows a graph of the typical dropout voltage at various currents but does not list a max dropout voltage. 2) It lists a max output current of 5A only when the Vin - Vout is 10V or less (then your minimum output voltage is 23V. It...
  3. audioguru2

    0-30 Vdc Stabilized Power Supply

    There was a thread about modifying this project for 5A output. Use the latest schematic. Use a 200VA 28V transformer, three output transistors with emitter resistors and use a 0.27 ohm 10W resistor for R7. I think 20,000uF to 24,000uF is good for the main filter capacitor.
  4. audioguru2

    Transistor collector current

    A class-A transistor has a fairly high output impedance which is its collector resistor. An emitter-follower has no voltage gain but has a low output impedance. Because the NPN transistor pulls up strongly but the emitter resistor pulls down poorly then it does not drive a low impedance load...
  5. audioguru2

    question about Low Pass Filter

    No. You need to calculate the amount of attenuation. One filter might pass the cutoff frequency of the other filter then the attenuation is only -3dB.
  6. audioguru2

    0-30 Vdc Stabilized Power Supply

    The 200 ohm load resistor has only 223mA to only 274mA in it but the voltage dropped over 10V so your transformer must be cheap and very small. It cannot be used for this 3A project. The supply is about 49.7V. Without a transistor and load, the zener diode and the 100 ohm resistor have a current...
  7. audioguru2

    diy 2.1 pc speaker

    The numbers are from the sales department. The distortion is a horrible-sounding 10%, the BTL speaker is only 4 ohms and the single speakers are only 2 ohms each. The power with only 0.5% distortion into 8 ohms is only 11W for the BTL output and only 3.1W for each of the single-ended outputs...
  8. audioguru2

    joule thief circiuts

    Why are you using the high voltage circuit to charge low voltage batteries?
  9. audioguru2

    joule thief circiuts

    All my schematics are in a PNG file type. Then they are much clearer than a JPG file type. I use a JPG file type for photos. Both file types upload easily. Which file types are your schermatics and photos?
  10. audioguru2

    joule thief circiuts

    Hi Steven, My solar garden lights have a circuit similar to the joule thief. I replaced the rusted away cheap Chinese Ni-Cad battery cell with a stainless steel American Ni-MH cell that lights the garden light all night long.
  11. audioguru2

    Technical help on building a low wattage heater.

    Low wattage and heater are opposite words. Low wattage makes no heat or very low heat. An electric heater uses a very high amount of power. My electricity is produced at Niagara Falls and by nuclear stations so it is fairly inexpensive. But most people near me heat their homes by burning...
  12. audioguru2

    Adding led brake lights

    I made a night light similar to your tailight with 36 Luxeon SuperFlux 4-pins LEDs running at 53mA each. Boy oh boy oh boy those LEDs get hot! Their max allowed current is 70mA. I mounted them on stripboard inside a compact cassette plastic box with many cooling holes. I made another nightlight...
  13. audioguru2

    0-30 Vdc Stabilized Power Supply

    Yes, but: 1) The datasheet for the TIP120 spec's its max base-emitter voltage loss only when its base current is 12mA. Your 1k resistor limits the base current to almost nothing when the darlington needs to be turned on very hard because its current and the current in the load are max at 3A. The...
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    Your positive unregulated supply voltage is too high when there is no load but is fine at max load. The capacitance multiplier circuit has a high output voltage when there is no load and its output voltage drops at max load. The opposite to what you want. Use a 43V zener diode to regulate the...
  15. audioguru2

    0-30 Vdc Stabilized Power Supply

    The latest version uses a 28V or 30V transformer. The voltage regulation of your transformer is poor. A 30V Hammond transformer is 31.5V without a load, not 34.4V. Simply calculate if it will cause damage: 1) 34.4VAC has a peak voltage of 48.6V and the full-wave bridge rectifier drops 1.4V to...
  16. audioguru2

    Adding led brake lights

    It looks good but I think the trail-lights will be very dim. Try it to see.
  17. audioguru2

    12v AC regulator (SCR bassed Shunt circuit)

    I assume you are using a transformer to step-down the voltage of your electricity mains to 12VAC. What load needs the 12vAC to be regulated? The output voltage of the transformer should not change much from when it has no load to when it is fully loaded unless it is poor quality and cheap. Is...
  18. audioguru2

    Adding led brake lights

    I don't know the spec's for your LEDs. If they are 2.0V and the supply is 13.8V then the output high of the lm324 opamp will be 12.4V and the output of the transistor will be 11.6V. Then the 330 ohm current-limiting resistor limits the current to 29mA and dissipates 0.28W so it should be rated...
  19. audioguru2

    Adding led brake lights

    Red LEDs are 1.7V to 2.0V each. Then 5 can be connected in series for 8.5V to 10.0V. A current-limiting resistor for the turn signals will be (13.8V - 8.5V)/25mA= 221 ohms which is not a standard value. Use 220 ohms/0.25W. This is one string of 5 LEDs that draws only 25mA. If you want 7 LEDs...
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    Maybe. But it might get too hot. U2 works hard but U1 and U3 do not. You need to calculate how much heat they produce to see if it is OK or if a single MC34074 quad opamp will fry.
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