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  1. audioguru2

    "Power?" Inverter

    MP and Ante, You made very good points about the transformer. Although the author recommended an over-rated 15A transformer (15A X 24V = 360W), he did mention re-winding a powerful microwave transformer. Maybe it is the transformer that produces the power, not the transistor circuit.
  2. audioguru2

    "Power?" Inverter

    Ante, I agree that a power circuit will have a variation in its performance if incorrect wiring techniques are used, such as moving a computer's power-supply into the next room without considering the the voltage-drop of the long wires. A power circuit will also have varying results if the...
  3. audioguru2

    My 120 Watts Power Inverter

    Kasamiko. Yes, the 2N3055s will be fine for this project since they must conduct only 10A. Please let us know how well it works.
  4. audioguru2

    12 volts led power input indicator circuit

    Hotwaterwizard, If the capacitor is discharged, and you apply power at the time that the AC voltage is at its peak of 170V, the LED must pass 1.7A for a moment. If you turn-off the power when the AC voltage is at its peak of one polarity, then while the capacitor is charged, apply the power when...
  5. audioguru2

    Need help with 2 ideas

    Stuee, 1) Ammeter: Meter manufacturers should have a current-shunt that you connect in series between the amplifier and battery. To allow for a voltage-drop of 0.1V at 100A, the shunt must be 0.001 ohms and be able to dissipate 10W. Then you connect a digital voltmeter having a full-scale...
  6. audioguru2

    Night rider scanner

    Nettron, Have you considered distorting the ramp so the LEDs slow down at each end like a pendulum?
  7. audioguru2

    Night rider scanner

    Nettron, Don't use the ramping voltage of a 555's timing capacitor to drive an LM3914 because it is not linear with time. It would start counting the LEDs quickly, then slow down when nearing each end. The integrator output of a dual-opamp triangle-wave generator is perfectly linear.
  8. audioguru2

    How do I make a dc circuit auto-off after 60 minutes

    Uman, A very low-power CD4060 oscillator/counter chip can give a short pulse after 60 minutes if its oscillator is set to 273Hz. This pulse can trip a latch that controls a transistor that feeds power to your circuit. A simple 2-diode OR gate can be connected to the CD4060's reset pin, one diode...
  9. audioguru2

    My 120 Watts Power Inverter

    Kasamiko, Your 2N6124 and MA21 transistors should be OK. I couldn't find a data-sheet for a DM74HC74, but all "HC" chips that I have seen have a maximum operating voltage of only 6V. "LS" and "HC" chips are made for extremely high speed so why use them here? An ordinary old 74C74 or 4013 will...
  10. audioguru2

    Night rider scanner

    Nettron, We have a 6-LED knightrider circuit in our projects section. The 4017 counts forward lighting LEDs 0-5, and diode gates are used to light those LEDs in reverse order while the 4017 continues its count of 6-9. From a 9V battery, the 4017's outputs are current-limited to about 11mA, so a...
  11. audioguru2

    ttl or gate

    Hotwaterwizard, Your very nice circuit actually is RTL, not TTL. I hope that Telecombug doesn't lose marks for that oversight. Kevin, Do you see how this OR gate works? It is simply that one transistor OR the other transistor OR both transistors turn-on the LED. There is no phase-splitter.
  12. audioguru2

    OPAMP questions

    OOOOps Kevin, The opamp roll-off is 6dB per octave (each doubling of frequency) or 20dB per decade (ten times the frequency).
  13. audioguru2

    OPAMP questions

    Kevin, The input capacitor, if used, to an opamp circuit is external to the feedback and therefore has no effect on the high frequency roll-off. The input capacitor, souce impedance and opamp's bias resistor determine the low frequency phase-shift and roll-off. Where did you get 40dB from? Most...
  14. audioguru2

    Rocker Switch Query

    gEcky, Did your switch melt? Perhaps it was poor quality. The transformer may have a short from primary to secondary which would cause your problem, and is VERY DANGEROUS. Check that transformer and use a quality switch.
  15. audioguru2

    Night rider scanner

    Nettron, Nice circuit. But 5 chips (the 5th is a 5V regulator) just to flash leds? The original knightrider car probably used light-bulbs. I would guess 8 to 10 of them.
  16. audioguru2

    My 120 Watts Power Inverter

    Kasamiko, Oh, oh, I see a problem: 1) When one transformer wire is pulled up to 11V by its conducting output transistor, then the other transformer wire is forced to -11V by center-tapped transformer action. 2) The output transistor that has its emitter forced negative, should be turned-off, but...
  17. audioguru2

    HELP ? ATX PSU LEADS

    MP, In this series circuit that will have extra wire resistance, where is your "more" current going to go? See my example #1 to see that the current is LESS when wire resistance is added to the loop. Why is a more powerful PSU needed? With more wire resistance, the current and power will be...
  18. audioguru2

    My 120 Watts Power Inverter

    Hi Kasamiko, That's a nice design. But the oscillator/flip-flop is rather complex and U2 is operating at a supply voltage that far exceeds its rating. The 4047 from the other project is better suited here. The MJ15015s are expensive and your circuit doesn't need its high ratings, except it can...
  19. audioguru2

    water pump

    EDY, Your problem is not the cables in your home, it is the cables or connections that FEED your home. The light-blink may be the 1st symptom of many more problems to come if those cables or connections are bad. The undergound wiring for my neighbourhood had to be replaced because it became...
  20. audioguru2

    My 120 Watts Power Inverter

    I don't see anything. I'll wait for it to be converted. Kamasiko, Have you measured its output at full load? At full load, does anything get hot?
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