Search results

  1. audioguru2

    Electronic Stethoscope

    Hi Dj, Did you substitute any parts from the parts list? Everything with the ground symbol on the schematic must be connected together. Since the LED stays on for a while, it indicates a DC problem. Measure the DC voltage at the outputs of opamps U1a and U1b. It should be very close to the...
  2. audioguru2

    Gas turbine bike.

    Hi Ante, I randomly surfed the German guy's turbine site. He and his friend must be millionaire machinists, because they are playing with carbon-fiber turbine blades, ceramic bearings and titanium. Can you imagine someone flying around wearing one of his "turbine belts"? Some of his turbines...
  3. audioguru2

    5 x LM338K

    Shahriar, An LM338K is a regulator in a power transistor's metal case. While a 2N3055 transistor is rated to dissipate 115W when its case is somehow kept at 25 degrees C, the LM338K is rated to dissipate 100W for the same condition. Of course heatsinks aren't perfect and heat-up, so the power...
  4. audioguru2

    Capacitor Size Matter?

    A larger new capacitor has a better ripple-current rating. If the capacitor is used as the rectifier filter in a high current power supply, It will have a high ripple voltage across it because its charging and discharging currents are high. A small capacitor will overheat and fail. You might...
  5. audioguru2

    Impedance matching

    Yes, any load on a transistor stage reduces its output level and increases its distortion. I showed this transistor discussion in your other post but here it is again: http://www.dself.dsl.pipex.com/ampins/discrete/discrete.htm
  6. audioguru2

    Choice of small signal BJTs

    Yes, that is why opamps use so many transistors. Class-A transistor stages produce even-harmonics distortion like I showed before with a voltage input. Transistors are non-linear, so push-pull stages are used in opamps to eliminate even-harmonics distortion. Current sources are used instead of...
  7. audioguru2

    Impedance matching

    Good audio circuits never match impedances from one stage to the next. A 10k load on a 10k source reduces the signal voltage to half. If you have more than a few stages then the signal is reduced nearly to zero. A transistor's collector and its load resistor are a medium impedance. It usually...
  8. audioguru2

    Choice of small signal BJTs

    Do you honestly have a pure current source as an input to a transistor? Don't you also feed it voltage swings? Then look what happens to the distortion of any transistor with a pure voltage input and the transistor circuit doesn't use any negative feedback:
  9. audioguru2

    i need help extending the keys finder project. can someone help me out????

    A white LED needs more than the 3V of the battery, so it will need an additional voltage stepup circuit for its power. Build this circuit 1st then you can build a light circuit later. From the Whistle Responder article: "This device beeps intermittently for approx. two seconds when a person in a...
  10. audioguru2

    Inverter Circuit 12V DC to 230VAC Sine Wave

    You ain't going to see a pic of me! I look something like your pic of Einstein, except about 20 or 30 years younger. ;D
  11. audioguru2

    Digital Remote Thermometer

    The other topics we talk about use ferrite transformers that are much bigger. They should give you an idea about what you need.
  12. audioguru2

    5 x LM338K

    Yes, if you don't adjust the output voltage very much. The problem is cooling them. With a huge heatsink and high velocity fan, each one can dissipate only about 50W. So the 5 of them can dissipate only about 250W and therefore the max difference between the input voltage and output voltage is...
  13. audioguru2

    Design of Fridge alarm control system

    Hi Edward, You could add a complicated motion detector circuit or a fairly simple optical circuit that detects moving shadows. Then this added circuit could be used to gate the alarm.
  14. audioguru2

    i need help extending the keys finder project. can someone help me out????

    Hi Logan, Welcome to our forum from that other one. ;D You got the projects' links and their titles mixed-up. The Keys Finder project has a serious problem: It requires that you whistle at a frequency that the piezo transducer is the most efficient, about 4kHz. You nor anybody can whistle at a...
  15. audioguru2

    led lamp

    Iceman, Five days ago you said: "the project states that for every 4 led's there must be 2 aa batteries. [where a set is 4 led's to 2 aa's] this is a requirement that must be meet." Therefore I designed a voltage stepup circuit for you since the LEDs need more voltage than two cells can supply...
  16. audioguru2

    Inverter Circuit 12V DC to 230VAC Sine Wave

    Aren't we way off the topic? Where's the sine wave? ???
  17. audioguru2

    Help for power supply.

  18. audioguru2

    Gas turbine bike.

    Thanks Ante, I liked the afterburner flame on the pulsejet and especially the huge flameout when it ran out of gas. ;D What a way to waste fuel. Using its expansion when it leaves to cool beer!
  19. audioguru2

    NiCd Battery Powered LED Lamp

    They certainly won't be bright at only 0.5mA! 20mA is usually used. When you stepup the voltage then you also stepup the battery current. The voltage stepup converter gets warm which wastes power that must also be supplied by the battery. Ante recently posted these circuits. The 1st one...
  20. audioguru2

    Electric Energy Saver Device

    A circuit that improves a poor power factor from a huge motor? Does your power useage meter even measure the power factor? Probably not unless you live in a factory.
View older results
Top