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  1. audioguru2

    help me please??? table hockey game...

    Hi Mintx, Since you are using a timer, don't you think it is best to be able to see it progressing? How about using a 555 timer IC with a constant current source transistor charging its timing capacitor linearly. Then use an LM3914 bar graph IC to display the time stepping up or down? When the...
  2. audioguru2

    help me please??? table hockey game...

    Hi Mintx, A countdown timer with display is fairly complicated for a noob. In our projects section is an example of a 99 seconds count-up timer. http://www.electronics-lab.com/projects/oscillators_timers/014/index.html A 2 minute countdown timer would be more complicated.
  3. audioguru2

    capacitor?????

    The caps are wired in series to give a very high voltage rating. Therefore they must be this extremely low leakage current type. The caps must supply very high current pulses. Therefore they must be this very low ESR type.
  4. audioguru2

    help me please??? table hockey game...

    Hi Mintx, Welcome to our forum. ;D Do you need the circuit for a 2 minute countdown timer? You could use a couple of 74LS04 inverters to make an accurate 32kHz crystal oscillator, and a bunch of 74LSxx counters to heat your room and make a 2 minute countdown timer. Or use a low power Cmos CD4060...
  5. audioguru2

    LM3914 pspice library

    Hi Maliki, National Semi doesn't have a spicy ( ;D) model for their LM3914. I looked on Google for Spice and then Pspice Model For LM3914 and found many people asking for a model too. One guy found a similar model to pspice online at a university. There are many French links. Parlez vous...
  6. audioguru2

    query abt plant watering watcher I

    Hi Meshal, Welcome to our forum. ;D I and others have built the 1st version of the circuit and it didn't work: 1) Many makes of its IC don't work with a new 3V battery and the Motorola IC that does work at 3V fails when the battery voltage runs down a little. 2) The circuit doesn't dim its LED...
  7. audioguru2

    i have a question

    That's a good interface circuit to protect the sound card from damage, except its output voltage swing of up to 11V positive or negative might still cause damage. Check the absolute max input voltage spec for your sound card. The circuit will also work fine with a positive 5V and negative 5V...
  8. audioguru2

    Design and construction of 3kVA inverter incorporating a 200Ah battery

    Hi Musty, Welcome to our forum. ;D The biggest problem with building a 3kW inverter will be obtaining a large, very expensive transformer. It will probably need to be custom-made for you. For the design, you need to determine its battery voltage. The inverter will probably be 80% efficient...
  9. audioguru2

    FM Radio

    The new Philips FM radio ICs had tiny surface-mount packages and didn't have a tuning control. They scanned and stopped at the next station. They don't make the scanning ones any more, I guess because they were copied in China. They sell the new TDA7010 in a surface-mount package and it seems to...
  10. audioguru2

    30vac to 30vdc converter

    That is 14.4kW! You said your power supply generator is 30vac @ 32 amps, which is only 960W. Will you use more than 15 generators to power it all?
  11. audioguru2

    FM Radio

    Like the project says, steal a varicap diode from an old TV tuner. Do you know where to get an old TDA7000 radio IC? It also hasn't been made for years.
  12. audioguru2

    FM Radio

    www.howstuffworks.com www.google.com
  13. audioguru2

    Multiple Switching Help!

    Hi Nickname, Welcome to our forum. ;D You could use a flip-flop for each switch. Pushing one button would Set its flip-flop and Reset the rest of them through a coupling capacitor to each one. You would need a simple circuit to reset them all when power is first applied. A CD4013 has 2 flip-flop...
  14. 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...
  15. audioguru2

    Internet Problems

    Hi Staigen, When I worked for a tele-conferencing company, everything had a backup except the main fiber-optic feed from the telephone company. It got broken during street repairs and put us out of business for a while. We lost some major customers. It would be useful if our site had another...
  16. audioguru2

    Internet Problems

    Hi Staigen, Nope. Our site's server might be under a sea of muck in New Orleans, and our server's host might be flooded out of business and unable to service it. :'( :'( I'll wait for my ISP to report what they find. The problem might be an internet hub that is under a sea of muck that might be...
  17. audioguru2

    30vac to 30vdc converter

  18. audioguru2

    NiCd - NiMH Charger

    That's the way to do it! If you want to charge a battery then use a battery charger IC. It does everything correctly with its 2193 transistors. It can Fast Charge then when the battery is fully charged it automatically switches to a selectable trickle current. It can be operated linear or in...
  19. audioguru2

    NiCd - NiMH Charger

    Hi Alun, No problem for both regulators. The project http://www.electronics-lab.com/projects/power/037/index.html says to use a high input voltage. I don't know why.
  20. audioguru2

    Linear Voltage Regulator Design

    And you also save money if you use a dual MC34072 for U1 and U2. A dual costs just a few cents more than a single opamp. ;D
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