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  1. audioguru2

    500W 12v to 220v Inverter

    Hi Photoar, You made my corrected circuit that has been on the site for nearly 3 years until it was changed recently. Look at the changed one in POWER CIRCUITS in our PROJECTS section. It is missing important parts and its frequency determining parts values are wrong. The transformer is a...
  2. audioguru2

    500W 12v to 220v Inverter

    The "500W" inverter schematic now on our site does not have enough output transistors for 500W output. Also its output transistors must be matched. 500W output. 83% efficiency is an extra 100W of heating. Total= 600W. 600W/12V= 50A. The output transistors must conduct 20A-25A each but their...
  3. audioguru2

    High Power LED Mood Lamp

    Its manufacturer warns that it might  blow up if its absolute max rating is exceeded. We are talking about current, not heating. The PIC does not have a higher current rating for pulses like the transistors and LEDs do. It is not necessary to exceed the 25mA max output current rating. A 680 ohm...
  4. audioguru2

    Electronic Eavesdropping Devices Detector

    Did the frequency of the tone change: 1) When you removed the antenna? 2) When you turned down the sensitivity control? 3) When you replaced the MC3403 IC? What resistor value did you try for R6? Do not connect the speaker terminal 2 to the positive supply. The pcb is different from the...
  5. audioguru2

    dancing leds with counter

    Just use a current-limiting resistor. A 3V LED is 3V. Its max current is probably 30mA so connect a 240 ohms resistor in series with it and the 9V battery and its current will be limited to 25mA. A 270 ohm resistor instead will limit the current to 22.2mA. We have a simple Sound Level Meter...
  6. audioguru2

    Electronic Eavesdropping Devices Detector

    Hi Eplanet, Before pin 1 of the IC was 5.0V, now it is 1.29V. What did you do to change it? Pin 1 is supposed to be 0V without any signal. When a signal is weak then the voltage will be small and the tone will be a low frequency growl. When the signal is stronger then the frequency of the tone...
  7. audioguru2

    Redesign Elektor gigant2000 Amplifier

    Nearly all excellent audio amplifiers are class-AB. Class-B has crossover distortion, class-AB doesn't. A few very hot amplifiers are class-A.
  8. audioguru2

    500W sine wave inverter design

    The car batteries over here for the big cars must be bigger and more powerful than your little skooter batteries over there. I have never seen a car battery with a capacity as low as only 50Ah.
  9. audioguru2

    white led

    Hi Pier, you cannot be certain the forward voltage of each LED is 3.5V since each one is different. They might be 3.9V then 6 need 23.4V. also, the transistors in the current regulator need at least 1V to work. So use 24V or 25V. You don't need a high voltage darlington NPN power transistor and...
  10. audioguru2

    2 5V power source for a circuit

    There is no positive or negative adapter. They all have two terminals. it is their plug polarity we are talking about. Is the center pin positive or negative?
  11. audioguru2

    2 5V power source for a circuit

    I have never seen an AC adapter with its DC grounded from the AC wall socket. Usually the DC is isolated. In Canada an AC adapter has two AC pins, hot and neutral, but no ground pin.
  12. audioguru2

    2 5V power source for a circuit

    You can buy adapters with the center pin positive or the center pin negative. Yours is positive. Maybe your circuit uses diodes to separate the supplies.
  13. audioguru2

    my gcse project

    There are temperature transducer ICs available. An ordinary silicon diode has its forward voltage drop about 3mV for each degree C rise in temperature. PTC resistor. NTC resistor.
  14. audioguru2

    How easy to add Transmitter & Receiver Pair?

    You could make a simple infrared remote receiver that won't work in sunshine but would respond to the remote transmitter for the TV, the TV cable box, DVD player, CD player, and almost every other remote transmitter. You could make a complicated infrared remote receiver and transmitter that...
  15. audioguru2

    Redesign Elektor gigant2000 Amplifier

    The 2kW amplifier uses many extra parts to handle the high voltages and high currents. For only 60W it is best to design or copy a circuit for only 60W. There are many excellent medium-power amplifier ICs available. St Micro and Philips make over 100 of them. The TDA7294 is 70W and has Mosfets...
  16. audioguru2

    Portable mic modification help

    I have never heard of a regulated  AC adapter with a voltage output of only 1.5V and a current output of only a few mA. Why don't you use a rechargable Ni-MH battery cell? New AAA cells have a capacity of 900mAh which is the same as a new alkaline cell. The voltage starts lower but the average...
  17. audioguru2

    2 5V power source for a circuit

    Usually the positive is switched, not the ground. It could be either way since the jack doesn't have polarity.
  18. audioguru2

    2 5V power source for a circuit

    The barrel of the plug pushes the spring contact #2 away from contact with terminal #3. Terminal #3 is the internal battery which is disconnected when the adapter is plugged into the jack.
  19. audioguru2

    2 5V power source for a circuit

    An adapter jack with a switch in it looks the same as one without the switch except it has a 3rd terminal. Here is a pic of a chassis-mount switched power jack. They are also made for pcb mounting.
  20. audioguru2

    Redesign Elektor gigant2000 Amplifier

    Your link doesn't work. Download the schematic yourself as a clear GIF or PNG file type, then attach it here.
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