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  1. audioguru2

    High Power LED Mood Lamp

    Are the resistor values correct in this nice new project? http://www.electronics-lab.com/projects/games/005/index.html The red LED has a forward voltage much less than the green or blue but it has the lowest current-limiting resistor value. Therefore if the transistor saturates then its current...
  2. audioguru2

    Audiogurus opinion of inverter

    Hi Ante, This inverter will heat with about 100W so it will try to draw 600W. That is 50A from a 12V battery. As I said before, then the output transistors will try to conduct 25A each! But their max rating is only 15A. Do you think they will blow open or they will short? If the load is only...
  3. audioguru2

    Theory discussion moved from Q/A

    Try measuring the current gain of a few hundred 2N3055 transistors to find one with a gain high enough to allow the little 2N2219 to be its driver in the power supply project. Try ignoring the very high ripple when its output voltage is only 25VDC and its current is more than 2.5A. The project...
  4. audioguru2

    I need Help

    Why did you select such a high frequency? Not many parts work so high and I can't even think that high. You might cook yourself with those microwaves. ;D
  5. audioguru2

    Upload Folder is Full

    Lately, a few people have not been able to attach things and get an error message "Your Upload Folder is Full". I understand that webspace has a cost, and a few of us make a lot of attachments, but if we are limited in the amount of attachments we can make then maybe we should chat on other...
  6. audioguru2

    Sound Level Indicator

    Hi Giroup, Why don't you make my Sound Level Indicator project? http://www.electronics-lab.com/projects/motor_light/009/index.html I used 20 very bright red LEDs but it would also look good with ultra-bright blue or green only 10 LEDs.
  7. audioguru2

    pc Speed Test

    Hi Guys, I found a small program that calculates pi to umpteen decimal places of accuracy. My Pentium4-2.97GHz pc does its 2M selection (click on upper left corner to select) in 1 minute, 43 seconds. With Norton, my anti-spyware and everything else disabled, it took a few seconds longer. My pc's...
  8. audioguru2

    Keys Finder

    Nobody has talked about this project for a while: http://www.electronics-lab.com/projects/misc/002/index.html It has very high gain when the piezo sounder is used as a microphone and only a little filtering. I wonder how well it works. Recently my daughter brought me a Keys Finder that she got...
  9. audioguru2

    LM324, LM358 crossover distortion

    In the datsheet of Mitsubishi's copy of National's LM358 low power dual opamp (half an LM324 quad), a very good description is made about why and how much crossover distortion is caused, and a method to reduce it. They show an awful full output frequency bandwidth to only about 6kHz at 10%...
  10. audioguru2

    Bass Extender

    Are you thinking about getting a subwoofer and amplifier for it to add more deep bass to your sound system? Years ago I wasn't satisfied with the "ordinary" bass output from my sound system at home that uses pretty good manufactured speakers with 8" woofers and some speakers that I made myself...
  11. audioguru2

    2N3055 Power Amplifier

    This project http://www.electronics-lab.com/projects/audio/042/index.html is a nice, simple amplifier that uses bootstrapping to increase its positive-going output swing to maximum. Its idle current is adjustable with the 500 ohm pot to operate the output transistors in class-AB for reduced...
  12. audioguru2

    Problems lately accessing this site

    Does anyone else have the same problems here as me? ??? ??? Lately (the past week or two), when I click on a reply notification in e-mail, my IE6 says "Loading Page" forever and nothing or our site's background schematic and only the top part of a page appears on my screen. Sometimes the IE6...
  13. audioguru2

    Sequential Timers with PWM Motor Speed Control

    Hi Guys, I've finally finished building the electric model airplane I won. ;D It is styrofoam and had a lot of parts to be joined with special glue and epoxy. I painted it with 4 brushed coats of shiny "red hot" latex house paint. It has a 3A geared electric motor that swings a 10" prop and is...
  14. audioguru2

    3-colours LED Solar Lights

    Hi Guys, I finally bought some solar garden lights. Hey, they are new and were on sale for about 11 bucks. I can't make them so cheap and look and work as well. They aren't the expensive brushed nickel ones my neighbour has. Those ones light an amber LED very dimly for only a couple of hours...
  15. audioguru2

    Automotive 12V to +-20V converter

    Nice new project: http://www.electronics-lab.com/projects/automotive/012/index.html Its author claims that an audio amp can supply 50W to an 8 ohm speaker with a +-20V supply. I disagree. A typical amp can supply only 17.6W to an 8 ohm load at clipping when powered by +-20V. About the same...
  16. audioguru2

    Motorola Hi-Fi power amplifier

    Hi Guys, We have a nice new audio power amplifier project: http://www.electronics-lab.com/projects/audio/041/index.html I think the author makes an error when he says to put a current meter on the output and adjust the trimpot for zero current reading. I think the adjustment is to reduce offset...
  17. audioguru2

    Electrolytic cap polarity markings

    Hi Guys, What's going on today? For all my life I have marked the "+" wire on electrolytic caps of schematics and layouts. All my old Philips caps are marked "+" and "-". Now I realize that today's caps are marked with a line of negative signs, "------". Who changed it and why?
  18. audioguru2

    240W Class-D surface-mount amp IC

    Hi Guys, They take a 4-channel class-D amp that operates its PWM at 385kHz, run the channels bridged to get a high-power stereo amp, then parallel those two bridged amps to get 240W output. Fairly difficult. Then they integrate the whole thingy into a tiny surface-mount package! The package...
  19. audioguru2

    Deja-vu, reply to replies

    Hi Guys, Today I received about 8 e-mails from this site for links to topics that I was the last person to make a reply. A couple of topics that I replied to hours ago and a few that I was the last person to make a reply nearly a year ago! Is anyone else getting these phantom e-mails from the past?
  20. audioguru2

    Transistor distortion and reducer circuit

    I found this info about the horrible distortion of a transistor without negative feedback. I have seen the distortion many times on my 'scope but didn't measure how much. Here the distortion is shown to exceed 15% and shows a way to reduce it without adding negative feedback which would also...
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