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  1. audioguru2

    A sleep Timer

    Hi Walid, Pushbutton P1 is connected to the positive supply. When it is pushed, it applies a positive voltage to the base of Q2 through D3. Then Q2 turns on and it turns on Q1. Q1 keeps Q2 turned on and Q2 keeps Q1 turned on. A positive pulse to the emitter of Q2 turns off Q2 and then Q1 also...
  2. audioguru2

    Automobile ignition power transistor

    Good idea, Ante. ;D I saw my old spark plug wires at night sparking all over the place from small cracks in the insulation. The car started quicker and ran a lot smoother with new wires.
  3. audioguru2

    High Power LED Mood Lamp

    Hi Gramo, You have read the datasheet for the PIC. You saw that it does not have a higher pulsed max current rating like a motor and a power rectifier do. Absolute maximum means absolute maximum, not "sometimes". Read the forum of the author of our Mood Lamp project. He forgot to use base...
  4. audioguru2

    High Power LED Mood Lamp

    MP: What is a degree in theory? I have a Bachelor of Electronic Engineering degree from Ryerson University in Toronto, Canada. I never had a mentor so I did not become a P. Eng. I worked at designing communications and sound systems for my entire career. I am an old geezer and have been retired...
  5. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    If your inverter is efficient then it doesn't waste much power as heat because its Mosfets switch nearly completely on and off and do not operate linear. Power= Volts x Amps. Amps= Power/Volts. Input power from the battery = output power to the load plus heating power. Example again: 500W...
  6. audioguru2

    Electronic Eavesdropping Devices Detector

    The opamp with a DC gain of 4,545 is rediculous. The voltage-controlled-oscillator is the same as the one in the datasheet for the old LM324 quad opamp. Replace the MC3403 quad opamp and the problem will be better, it will be worse or it might not have a problem anymore.
  7. audioguru2

    High Power LED Mood Lamp

    MP, Why do you disagree with manufacturers and use excessive supply voltage for opamps and excessive output current on Cmos microcontrollers and on power transistors in inverters?
  8. audioguru2

    A sleep Timer

    Hi Walid, Sorry, I didn't calculate the CD4060 timer. The two transistors form a thyristor. The push button turns on Q2 which turns on Q1 They are connected together so both stay turned on. Applying a positive pulse to the emitter of Q2 turns it off then Q1 no longer has anything to keep it on...
  9. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    You cannot use a resistor in series with the transformer to reduce the output voltage, the high current will create too much heat. Use Pulse-Width-Modulation at a high frequency to control Mosfets which adjust the average voltage that is applied to the transformer. Then since you will have PWM...
  10. audioguru2

    12 V DC to a 220V AC Inverter AMplfier Design

    The stepup of the transformer determines the output voltage of an inverter that is simple and doesn't have voltage regulation. The load determines the current in the transformer, in the Mosfets and from the battery. The Mosfets are just switches that draw DC power from the battery and pass AC...
  11. audioguru2

    Redesign Elektor gigant2000 Amplifier

    You don't just remove transistors and reduce the power supply voltages to reduce the power of an audio amplifier. With reduced supply voltage then many resistor values will be too high to supply enough current and each resistor will need to be analysed and a value selected for it to perform its...
  12. audioguru2

    High Power LED Mood Lamp

    The author's supply current graph indicates a max peak current of only 232mA that is far less than the max current ratings for the LEDs which is 350mA x 3= 1.05A. My analog Mood Lamps use cheap ordinary LEDs but have a very bright max current peak of 300mA. Therefore in the source code what is...
  13. audioguru2

    Audio Preamplifier Design Project

    I think of audio opamps with very low noise, very low distortion and bandwidth to about 100kHz. I think of instrumentation opamps for low frequency hearbeats and DC weighting scales. Noise , distortion and bandwidth don't matter. Did you find an instrumentation opamp that would be good for an...
  14. audioguru2

    Electronic Eavesdropping Devices Detector

    A digital camera has a very low level digital signal inside. It would be difficult to detect it.
  15. audioguru2

    Redesign Elektor gigant2000 Amplifier

    Class-AB usually has a current of 50mA in each output transistor. This one has 90mA and has 7 pairs of output transistors. Its supply is 140VDC so the quiescent power dissipation is only 88.2W. If its ouput can create 130Vp-p across 8 ohms then its peak current is 65V/8 ohms= 8.1A. For class-A...
  16. audioguru2

    Dancing LEDs 9V (Guitar Hero Project)

    Hi Habuki, Welcome to our forum. ;D I found a couple of things wrong with your circuit:
  17. audioguru2

    High Power LED Mood Lamp

    I understand that the mood lamp uses Pulse-Width-Modulation to dim the LEDs. The outputs of the microcontroller are pulsed. They don't need to have a current that exceeds the manufacurer's absolute maximum current rating. You don't understand??
  18. audioguru2

    0-30 Vdc Stabilized Power Supply

    Hi Adian, The peak voltage from the 30VAC transformer is only 44VDC when there is no load. A 50V capacitor should be fine. I selected a 63V capacitor because it was available on Farnell's site. You can use any value over 10,000uF. You can parallel capacitors for a total over 10,000uF if you want.
  19. audioguru2

    500W 12v to 220v Inverter

    With a 500W load, each 0.1 ohm emitter resistor dissipates 10W half the time. Their total power dissipation is only 40W (8% of the load's power). Then the transistors don't need to be matched to have the same current gain. Remove the resistors if you can buy matched transistors. With less load...
  20. audioguru2

    Redesign Elektor gigant2000 Amplifier

    Hi Shahriar, Nobody can hear the very low distortion from a good class-AB amplifier. Some class-A amplifiers have lower distortion and some have higher distortion. The famous brands make class-A amplifiers TO MAKE MORE PROFIT! They have bigger transformers and heatsinks. They have more output...
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