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  1. audioguru2

    LED Chaser 3 x 36

    Hi Shado, OOps, I'm sorry that I called you a shadow before. 1) At the top of this page are category buttons for Home, Projects, Articles etc. On the Home page, my latest (posted just a few days ago) chaser project is highlighted as an article. Down the right side are the newest projects, and my...
  2. audioguru2

    Speaker buzzing

    Hi Ante, I don't see a shield over the deflection coils, do you? ??? I just see some kind of plastic structure that holds the coils. ::)
  3. audioguru2

    help!

    Hi Vedran, My cordless phone stopped working and I fixed it by replacing its delicate quartz crystal. Nobody admitted to dropping it (it wasn't me) so at first I thought that lightning destroyed it like my dead wired phones, answering machines and clock radios. Look inside your processor to see...
  4. audioguru2

    LED Chaser 3 x 36

    Hi Shadowfax, Welcome to our forum. I have posted two chaser projects, but each uses only 10 LEDs. If you planned your LED's PCB for it, it would have been easy to sync the circles simply by wiring the LEDs in series. Then an LED at any position would be connected to the same LEDs in the other...
  5. audioguru2

    Speaker buzzing

    Hi Guys, Here is a pic of a computer monitor's or TV's CRT. The end on the left has the brightness amps mounted on a PCB that plugs into the pins of the CRT. That PCB is usually shielded because it has several pins with fairly high voltages on them for focus and screen grids. The brightness amps...
  6. audioguru2

    Negative charge pump

    Hi Kevin, I don't know what your transistors are supposed to do. 1) The transistors at the bottom are fighting each other because the NPN one is pulling to -7.3V while the PNP one is pulling to ground at the same time. They should be push then pull like the input stage. 2) That NPN transistor...
  7. audioguru2

    Speaker buzzing

    Hi Trigger, Ante is referring to the high voltage section of a monitor which is shielded to prevent any sparks from causing radio interference. I am referring to the "deflection yoke", which are coils mounted on the neck of the CRT to electro-magnetically move the beam. I have never seen those...
  8. audioguru2

    Speaker buzzing

    Hi Ante, Don't worry about the monitor. The deflection yokes of most CRT's are not magnetically shielded and the magnetic sawtooth radiation can be picked-up by other electronic items. It could be heard in my telephone's earphone even when it was unplugged. :o Maybe Yevgeni's computer speakers...
  9. audioguru2

    Speaker buzzing

    Hi Yevgeni, I think that the buzz is caused by the strong magnetic field that moves your CRT monitor's beam vertically. Try moving the speakers and their input cable a meter away from the monitor to see (hear?) the buzz go away. Don't the speakers have a shielded input cable? Pickup of noise...
  10. audioguru2

    Calculating voltage output of Capacitor in AC Circuit

    Hi Hamish, Balloons lifting weights with an air compressor? I just use hot air or helium. ;D Have you seen those radio-controlled indoor blimps? Helicopters lift stuff pretty well too. 1) The capacitor charges to the peak voltage of the transformer's output sine-wave, minus about 2V voltage...
  11. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Doctor Naldo, Hola, como estas. (My wifey is from Spain, but please don't talk to me in Spanish) 1) Your 10W resistor for R7 shouldn't burn when it dissipates only 4.2W, but it will get hot. 2) Sure the 2N3055 gets very hot when it dissipates 69W, but it is possible with a big heatsink (like...
  12. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Naldo, As Mixos and others have discovered, your project has very poor voltage regulation at higher output voltages and currents. That is why this thread is so long. When you measured its output with resistors for a load, did you set its voltage output pot to maximum? Your circuit has a...
  13. audioguru2

    UV exposure and white LEDs?

    Hi Kain, That's great! Red work-lights aren't needed anymore. Are you going to make a white LED desk-lamp? When you turn-off the desk-lamp, are you also going to have a white LED spotlight to light your path to the door? ;D
  14. audioguru2

    Electronic Eavesdropping Devices Detector

    Hi Sarge, Welcome to our forum. You are talking about detecting very high frequency microwave frequencies, where a short piece of wire is a tuned circuit and a short piece of metal is an inductor. Therefore a special wiring technique must be used (waveguides) that resembles plumbing. Also, parts...
  15. audioguru2

    Calculating voltage output of Capacitor in AC Circuit

    Hi Hamish, Welcome to our forum. The capacitor must provide the 3A to the load between charging pulses from the rectifier bridge so the voltage will have ripple while it discharges into the load then is quickly charged by the rectifier bridge. The formula is approximately 1V p-p of ripple for...
  16. audioguru2

    Neon flashes with the music

    The neon light bulb won't use much power but the little transformer that is used backwards will probably overload the amp and battery at low frequencies where its 8 ohm winding has poor coupling with the core that is too small. The 8 ohm winding will be like a dead short to the amp at low...
  17. audioguru2

    Negative charge pump

    Hi Kevin, I have always used everything within their ratings over my fairly long career and have never burnt-out a transistor, opamp nor LED. Perhaps your problems are caused by neglecting the ratings. I don't think it is possible to build a simple and efficient high-current DC voltage doubler...
  18. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Naldo, With 3A going through the 0.47 ohm R7, the continuous power dissipation is 4.23W, so a 5W resistor will be extremely hot. I suggest using a 10W resistor. A BC548 for Q1 is OK with your low transformer voltage. A TIP31A for Q2 will need a fairly small heatsink, about 4cm L by 2.5cm W...
  19. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Naldo, Good, I'm glad you fixed it. Suggested changes: 1) Your max output voltage with a 3A load is probably only 25V, you can get a couple more volts by changing R15 to 100 ohms. 2) You can also get more output if you change the rectifiers D1 to D4 to a 10A rectifier bridge module. 3) Even...
  20. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Naldo, Welcome to our forum. It sounds like R7 is open or a wrong value. It should be 0.47 ohm (a little less than 1/2 of 1 ohm).
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