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  1. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Rufinus, With the 20 ohms load connected, the voltage pot set to 25V and the current pot to half-way: 1) Measure the output voltage (pin 6) of U3. It should be high which is about +31.8V in your circuit. 2) Measure the input voltage (pin 3) of U2. It should be about +8.1V. 3) Measure the...
  2. audioguru2

    Why is so hard to mimic the Knight Rider scanner Effect?

    No. I recommend using two series current-limiting resistors for each LED with a capacitor to ground at their junction. Then one resistor charges the capacitor slowly which slowly brightens the LED, and the other resistor isolates the low (off) voltage from the gate so the capacitor slowly...
  3. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Rufinus, The LED is off so U3 is not reducing the output voltage, something else is. Maybe Q2 is destroyed by the very high current you had when the fuse blew. 1 ohm is much too low for testing. If the output voltage is 25V then it would try to draw 25A! Try 12 ohms to 20 ohms. If the current...
  4. audioguru2

    Why is so hard to mimic the Knight Rider scanner Effect?

    To make each LED fade on and off then each LED will need two series current-limiting resistors with a pretty big filter capacitor to ground from the junction of the resistors.
  5. audioguru2

    0-30 Vdc Stabilized Power Supply

    A 680 ohm load causes only 37mA if the output voltage is 25V. The current pot would need to be turned up to less than only 1% of its rotation for the circuit to begin regulating the cuurent. Use a much lower value for a test load resistor to make enough current for you to see if the current...
  6. audioguru2

    Help!! My Door Alarm is not work?

    The instructions say the wire diameter to use and says exactly how to make it. The instructions say 10mH which is ten milli-Henries. Micro-Henries is written as uH. Most radio frequency circuits like this one do not work on a breadboard because the stray capacitance and stray inductance are too...
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Rufinus, The current regulator has a max current output of about 3.4V if the value of the pot is a little high. You should increase the value of R18 to reduce the max output current to match the value of your fuse. Test the current regulator by turning down the current pot to about half...
  8. audioguru2

    white led

    Then it will be a 1.25V voltage regulator, not a current regulator. The datasheet shows how to make a current regulator and you had it almost correct before:
  9. audioguru2

    current and voltage out of phase

    I don't think an inductor reduces ripple in an AC power supply unless it is a PWM circuit. Then the series inductor blocks the high frequency but passes the lower frequency modulation.
  10. audioguru2

    help......how to build line follower colour sensor

    If the white line is not much brighter than the blue floor then use a red filter over the photo-detector to block the blue light. White has lots of red.
  11. audioguru2

    current and voltage out of phase

    Power supplies are usually DC and use a big filter capacitor or an inductor in series with the filter capacitor to block AC with the inductor and short the AC to ground with the capacitor to smooth the rectifier pulses. The resistance of the inductor reduces the output current available from the...
  12. audioguru2

    Why is so hard to mimic the Knight Rider scanner Effect?

    Hi Wellington, We have three or four Knight Rider scanner circuits in our projects section. Bill Bowden also has some. None use as many as 7 ICs as in this project. A real Knight Rider fades the lights from one to the next which is automatic when using incandescent fairly high power bulbs. LEDs...
  13. audioguru2

    white led

    Hi Pier, The output voltage of the LM317 current regulator is 1.25V higher than whatever is the total voltage for the two LEDs. Your 390 ohms resistor reduces the LED current to only 1.25V/390= 3.2mA which is way too low. 3.9 ohms would regulate the current at 320mA to 330mA. The 100uF...
  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Rufinus, What value and where in the circuit is the fuse that blew? Your current regulator is not working properly. It is supposed to sense the voltage across R7 caused by load current and reduce the output voltage so that the load current is the same as the setting of the current pot. U3 is...
  15. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Eggy, Good, you fixed it. Didn't you use a 24VAC transformer? How high does the project's DC output voltage go when it has a 3A load? What is its max output voltage without 100Hz ripple when it has a 3A load?
  16. audioguru2

    white led

    Yes, the LM317 will be a 320mA current regulator when the resistor is 3.9 ohms.
  17. audioguru2

    My 12 watt x2 stereo amplifier

    Hi Ben, Stereo speakers in the same box cancel the bass frequencies when they are connected "out of phase". When they are connected with the same phase then the bass is very strong without any cancellation. The size of the box must match the spec's of the woofer for good bass: 1) If the box is...
  18. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    Hi Kachew, 1) A square-wave inverter has the 12V from the battery switching back and forth in the primary of the transformer. The battery current is nearly continuous and is steady. Its output voltage has a peak value the same as its average value which is the same as the RMS voltage if it is a...
  19. audioguru2

    Ornament Gift with Color LEDs Design help?!

    Hi Kevin, 10 seconds ago I answered your same questions on another forum.
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    Is your -5.6V supply at pin 4 of U2 and U3 a negative voltage or is it a positive voltage? The LED is supposed to light only when the project is reducing the output voltage because it is regulating the current. It warns that the output voltage is being reduced. It also warns that the load wants...
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