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  1. audioguru2

    LED turn

    Hi Eplanet, You don't say the supply voltage and you don't say the max current for your LED. Most LEDs have a max current of 30mA but usually operate at 20mA to be bright. Some LEDs have a max current of 700mA. I made a circuit with a capacitor that charges slowly from a resistor when power is...
  2. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Hi Kachew, Which IC is burning? What is the DC supply voltage? If the supply is from a car then it has many voltage spikes. Connect a 16V 5% 1W zener diode and a 0.1uF ceramic disc capacitor across the supply pins of the ICs and feed the positive supply voltage through a series 47 ohms resistor...
  3. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    The output of each CD4001 NOR gate is supposed to go high for 1/4 of the time and alternate like this:
  4. audioguru2

    PhotoCoupler PCB hole

    Maybe the hole separates the high voltage side from the low voltage side of the circuit, so that current leakage on the pcb (when it is damp from humidity?) doesn't matter.
  5. audioguru2

    white led

    Heatsinks are not selected for their looks. They are selected by calculating how much cooling you need, then selecting one with the correct spec's. The manufacturer will say how many degrees C the semiconductor's case temperature will rise per Watt of dissipation when it is bolted to the...
  6. audioguru2

    hydroxy gas power supply/separating oxygen and hydrogen from water

    You can use a 100A power supply if you want. An electronic circuit takes only as much current as it needs. But if the load is shorted or the motor is stalled then the circuit might try to take more current than its rating. Then it should have a fuse.
  7. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Have heavy wires from the Mosfets to the battery connection, then separate wires from the pcb where the ICs are to the battery connection. Then the Mosfets have separate wires for their high current and the ICs also have separate wires for their low current.
  8. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    As I said before, the gate of a Mosfet needs to have a resistor in series to stop it from oscillating at a very high frequency which wastes power and makes it get hot. 47 ohms or 100 ohms is fine. Your schematic showed 1k resistors but 47 ohms or 100 ohms will make them switch quicker.
  9. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    The Mosfet is just a switch. It doesn't have voltage, the transformer has the voltage and the Mosfet shorts it to ground when it turns on. The pcb traces should be planned so that the very high current through the ground path from the Mosfets doesn't affect the ICs.
  10. audioguru2

    HiFi voltage etc..

    A CD player has an output of about 200mV RMS/283mV peak when it is playing very loud. If a guitar pickup is loaded with 1M ohms and is played very loud then its output will be about 1V RMS/1.4V peak. Calculate it. 1W into 8 ohms is 2.8V RMS/4V peak. 10W into 8 ohms is 9V RMS/12.7V peak. 100W...
  11. audioguru2

    Battery charger /need help

    Your battery with 3 wires might be rechargable lithium. The 3rd terminal might be a temperature probe to tell the charger to reduce the charging current to avoid a fire. You don't want to be near a lithium fire that occurs when a lithium battery is overcharged. The lithium fire makes very hot...
  12. audioguru2

    Electronic Stethoscope 2

    Hi Soly, Connect a switch to two values of filter capacitors like this:
  13. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Hi Kachew, A ceramic capacitor or a "green cap" is marked with the value coded; 220= 22pF, 0.022nF 221= 220pF, 0.22nF, 0.00022uf 222= 2200pF, 2.2nF, 0.0022uF 223= 22nF, 0.022uF 224= 220n, 0.22uF 225= 2.2uF I attach a logic timing diagram for your CD4047 and CD4001:
  14. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    The 220K is 220,000pF which is 220nF or 0.22uF. No. A Mosfet oscillates at a very high frequency if it doesn't have a resistor in series with its gate. It will overheat if you allow it to oscillate at a very high frequency. The value of the capacitor is too low and the value of the resistor is...
  15. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    The frequency determining capacitor should be a 5% (J) metalized plastic type. 10% (K) ceramic is fine for the 0.22uF capacitor. i think without the resistors infront of the mosfet doesnt affect much if the circuit?
  16. audioguru2

    0-30 Vdc Stabilized Power Supply

    Q4 is the main power transistor in the project. It acts like an automatically variable resistor. It automatically keeps the output voltage or output current constant even if the load current changes. It gets very hot when it has up to 30V across it and up to 3A through it which is 90W of heat. A...
  17. audioguru2

    0-30 Vdc Stabilized Power Supply

    It is not noise, it is a DC voltage that is up to positive or negative 18mV at the output of the project when the voltage control is all the way down. It is caused by the opamp U2's input offset voltage which could be from -6mV to +6mV and it is amplified 3 times by the circuit. The output...
  18. audioguru2

    Ft of the transistor

    The output of the transistor amplifying oscillator is the collector. If it is fed to the emitter and the transistor's base is at AC ground then the transistor is a common base amplifier and the feedback is positive and makes it oscillate. If you feed the collector signal to the base then the...
  19. audioguru2

    which amp to build?

    Hi Quincy, Those projects are pretty old and the old parts might be hard to find. It is too bad the first one has errors that were not corrected. I didn't analyse the second one. Newer designs are better. Here are two sites with good modern amplifier projects...
  20. audioguru2

    Electronic Stethoscope

    The LM386 was invented before PSPICE so there is not a model for it. If you made your own model then connect a 16 ohm load resistor to the headphones jack. Disconnect the LED, all it does is blink.
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