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  1. duke37

    help with power consumption.

    No, the power is the product of the voltage, current and the power factor. The motor rating does not say what power is actually used. The power factor will be high when the motor is heavily loaded but low when it is lightly loaded.
  2. duke37

    220V to 12V 2Amp power supply modification

    What superb pictures, how do you do it? You are only concerned with the low voltage side of the board. In the picture showing the TL431A, the sense terminal is on the left. From here there will be one resistor connected to the +output and one connected to the -output. What is the value of...
  3. duke37

    Creating a variable wien bridge oscillator

    I suppose that the LM386 could be called an op amp. However, the LM386 will have more power than the normal op amp and will require fewer components. It is designed to drive a speaker so that is the one to go for.
  4. duke37

    help with power consumption.

    The power will be less than the maximum motor power, it depends on the work the lathe is doing. Is it turning balsa wood or machining stainless steel?
  5. duke37

    Creating a variable wien bridge oscillator

    To get a variable frequency, you need to change two resistors together. Altering one only will change the gain and so will affect the sine wave. Commercial oscillators use a matched pair of linked resistors or use a two gang capacitor. Another way of getting a wide audio frequency range is to...
  6. duke37

    Motor run capacitor theroy with added PFC fun

    The motor will be wound to have the starter winding at 90deg to get the pole pieces between the main pole pieces. Thus a phase shift of 90deg would be best but I do not think that this can be fully achieved with a capacitor. If the capacitor is start only then look at similar motors to get an...
  7. duke37

    220V to 12V 2Amp power supply modification

    If the IC is a kA431, then the sense terminal will be at 5V. To get 29% more voltage across the 'top' resistor, the 'bottom' resistor from the sense terminal to negative common needs to pass 29% more current . This can be done by tacking a resistor of about three times its value across it.
  8. duke37

    resistor used as a fuse

    The resistor in line with the mains input limits the surge current when the bulb is turned on and the high voltage capacitor has no charge on it. I see no need to change this The 400V capacitor controls current to the circuit. If the current is not used, the low voltage capacitor has to take it...
  9. duke37

    TV Antennas

    A modulator is a device to mix two signals together such as an audio or visual signal onto a radio frequency. You do not need one of these. You do not need an impedance matching transformer if the system all works on 75Ω. My simple FM antenna is 300Ω and so I use 300Ω twin feeder to the...
  10. duke37

    220V to 12V 2Amp power supply modification

    The 10μF capacitor should be discharged with a resistor, say 10kΩ. The board is split with high voltage on the left and low voltage on the right linked by an opto isolator. To get a higher voltage, the feedback needs to be reduced or the reference voltage increased. What is IC2?
  11. duke37

    TV Antennas

    The best place for an antenna amplifier is at the antenna. Power goes up the co-ax cable. The signal can then be split to two cables in a more convenient place. The amplifier will not be needed if the signal is strong and may even cause problems. A splitter can as simple as a few resistors but...
  12. duke37

    Can someone help describe how this circuit works?

    The transistor drives the relay coil to turn the siren on. Pin 11 of the 4011 drives the transistor base when high. The truth table for the 4011 is on the left. You will need to find out how the capacitors chrge up.
  13. duke37

    equivalent for 2N4401

    The 2N2222 will probably do the job and is very common. What does your circuit require?
  14. duke37

    Connect Different Leds

    Yes, it limits the current by dropping the voltage. The led voltage and the voltage across the resistor must add up to your supply voltage. With a 5V supply and 2.2V led, the resistor must drop 5-2.2 = 2.8V. The resistor will then need to have a value of 2.8/0.7 = 4Ω. The power in the resistor...
  15. duke37

    Connect Different Leds

    The video shows the led being driven by a current source, you have a voltage source. It is a different convertor, controlling voltage and current. If the led needs 2.3V and you drive it with 2.3V it may work OK but it will get hot and then need 2.2V and the current will rise to destruction as...
  16. duke37

    Connect Different Leds

    You are doing something wrong! A led needs a certain voltage to work. If you exceed this voltage by a very small amount, then the current will be very high and it will go pop. You can control the current with a constant current supply rather than a constant voltage supply or use a resistor as...
  17. duke37

    Connect Different Leds

    To use 5V, each of the leds must be supplied separately. Calculate a resistance to give the required current from 5V. For example R = V/I so the red would need a resistor of 2.2/0.7 or about 3.3Ω. If you wish to reduce the brightness, try 5 or even 10Ω. Power in the resistor will be I*I*R or...
  18. duke37

    Soldering Problem

    Lead free solder needs a higher temperature than eutectic tin/lead solder.
  19. duke37

    Simple Motor Controller Circuit

    The internal diode does NOT do the same job as a flywheel diode but some mosfets use a zener diode in this position to limit the collector voltage. The normal internal diode conducts when the polarity is reversed.
  20. duke37

    Kayak stand with sensors ?

    What about a press button mechanical counter?
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