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  1. audioguru2

    capacitor?????

    The capacitors should all be exactly the same (value, type and manufacturer) to share the voltage equally. A 15uF cap would charge quicker to a higher voltage than the other 20uF caps. It looks like the caps are rated for a very high current, therefore must have a very low ESR.
  2. audioguru2

    I need to balance an amp HELP!!

    Hee, hee. ;D I don't have a fuse. I use foldback current-limiting when I get tired. Hee, hee. ;D
  3. audioguru2

    Choice of small signal BJTs

    I don't use transistors from radios and things. They have too many different types and I can't purchase them if I need more.
  4. audioguru2

    +/-15V power supply using LM317 and LM337 regulator ICs

  5. audioguru2

    Op.Amp. vs. Diff.Amp.

    There are only a few applications for differential amplifiers. A balanced input for a dynamic microphone's preamp would use a differential amp if you didn't want to use a transformer. Ordinary opamp circuits usually have only one input.
  6. audioguru2

    Choice of small signal BJTs

    I used to use BC547B and C and BC557B and C transistors when I worked for Philips, but they are hard to get in Canada. Now I use 2N3904 and 2N3906 transistors that are made by many manufacturers. The BCxxx  transistors have the advantage of selected current gain in 3 groups. The 2Nxxx...
  7. audioguru2

    +/-15V power supply using LM317 and LM337 regulator ICs

    Hi Cyw, Your circuit is correct for a dual-polarity supply having adjustable output voltages from 1.25V to about 27V. You don't need an input voltage as high as 30V when anything more than 18V will be fine. You don't need pots to adjust the output voltages when 2.7k (5%) resistors are fine to...
  8. audioguru2

    Op.Amp. vs. Diff.Amp.

    Hi Autir, An opamp is a building block with extremely high voltage gain and differential inputs. A differential amplifier is a circuit using a single opamp or 3 of them, with the inputs properly biased and with negative feedback for a certain defined voltage gain. Some differential amplifier...
  9. audioguru2

    Inverter Circuit 12V DC to 230VAC Sine Wave

    Wow! Would you like to design and build an efficient pure-sinewave inverter with voltage regulation and a ground-fault-interrupter, using PWM? ???
  10. audioguru2

    MICRO ANTENNAS

    My Nokia 6101 cell phone works on 4 frequency bands with a total of 299 channels, using GSM digital modulation. It supports e-mail and internet connection but my carrier company charges a fee for those services.
  11. audioguru2

    Inverter Circuit 12V DC to 230VAC Sine Wave

    Hi Sasi, Excellent! ;D How many kW can your inverter supply continuously? ???
  12. audioguru2

    MICRO ANTENNAS

    Hi Glen, My daughter gave me the free cell phone for my birthday present and also got a free one for herself by signing a 3 years contract for a low monthly price. We can make unlimited free local calls for 6 months, then after only evenings, weekends and calls to each other are free. She got...
  13. audioguru2

    MICRO ANTENNAS

  14. audioguru2

    0-30 Vdc Stabilized Power Supply

    A BC557 operates well within its ratings here. You must have had a weak one. With a positive unregulated supply of 40V and 6V on the output at 3A a single 2N3055 must dissipate 102W. It is rated to dissipate 115W when its case is held at 25 degrees C somehow. If yours was only warm then it was...
  15. audioguru2

    high and low voltage cut off with time delay

    Hi Sunny, Welcome to our forum. ;D I found the project: http://www.electronics-lab.com/projects/motor_light/042/index.html It says that the time delay is important and is missing from other similar circuits: "Its salient feature is that no relay hunting is employed. This draw back is commonly...
  16. audioguru2

    Need help building off this schematic.

    Overclocking with liquid nitrogen cooling? Pushing the 3.3V supply up until something goes POOF? ??? ;D
  17. audioguru2

    led lamp

    I've never seen nor heard of that BC-thingy, and in Australia? Also, he might endup with a ferrite AM radio loopstick. :(
  18. audioguru2

    Need help building off this schematic.

    It might be difficult to find a Mosfet that can conduct 20A when hot, and only about 6.7V between gate and source. You might need to try many from a bucket full of them to find one that works. :(
  19. audioguru2

    led lamp

    My schematic shows LEDs with about 3.3V. Most white or blue LEDs have a max voltage of 3.5V. Many that I've measured are actually about 3.3V.
  20. audioguru2

    led lamp

    Hi Ante, If a nubee can't find common stuff, where is he going to find a ferrite core or a low-saturation transistor? ???
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