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  1. duke37

    Motor controller fix- parts id

    Looks to be worth a try. Are the legs the correct distance apart? You may have to reform them, if so, do not bend near the capacitor.
  2. duke37

    Charge capacitor to a specific voltage

    Wikipedia has a chapter on zener diodes. You will need aditional circuitry for high powers or high accuracy. Specification required.
  3. duke37

    Charge capacitor to a specific voltage

    A diode from the panel to the capacitor will be all that is necessary to stop power going back into the panel when the light is low. To dump charge, you could use a zener diode at the voltage you want to limit. Most such diodes will be low power types but can be amplified with one or more...
  4. duke37

    JK Flip-Flop + D-Type Flip_flop

    To quote Don Lancaster If the D input is cross-coupled to the Qbar output, the flip-flop changes to the other state on the positve edge of the clock, behaving as a binary divider.
  5. duke37

    Autotransformers

    Yes, please sketch a schematic to show us what you wish to do. Specify input power and outputs.
  6. duke37

    JK Flip-Flop + D-Type Flip_flop

    I Googled Dt systems and found they make dog collars. I do not see what they have to do with flip-flops.:) You need to get a basic book on electronics to find out what flip flops do. They change two outputs over for each input pulse so can be used for a divide by two circuit and made into an...
  7. duke37

    Motor controller fix- parts id

    Oops 155 = 1500000 pF = 1.5μF. Replace with a non polarised 400V capacitor or better 1000V.
  8. duke37

    Baseball Scoreboard

    The LEDs do not need to be big but they need to be powerful and shine in the direction required.
  9. duke37

    Reverse Polarity Protection (some questions)

    Relays are very thirsty, I would not use them unless you have a powerful supply. The MOSFET circuit is very good with very little voltage drop and so very little power loss and so no need for a heat sink. A single diode can be used to protect the circiut but will not allow either polarity as a...
  10. duke37

    Ideas ?

    A relay which is started with a button, and will drop out when the mains fails will do. Such a system is used in motor starters. If you need an indication when the mains is off, then a battery will be needed.
  11. duke37

    Autotransformers

    What is supply E? An auto transformer does not give isolation so there is danger of shock. What is the input, is it mains? How do you get DC? Is this the input supply to an invertor? If the mains input goes to the transformer, then this will always be energised and a suitable led or bulb can...
  12. duke37

    Cockroft-Walton Voltage multiplier

    1000V DC in will give 1000V DC out minus diode drop. High frequency AC supply will give about 20 times the voltage at DC. Capacitors do not pass DC and will need a high frequency to give a low impedance. You will need high frequency diodes, 1N4007 will not do.
  13. duke37

    How do I run a dc motor slowly?

    I have measured the voltage across a DC motor and if low, supply a pulse of current. The pulses came from a transformed and rectified mains supply, switched with an SCR. This would run a car fan motor very slowly, limited by the motor cogging. Presumably, the higher the inertia, the lower the...
  14. duke37

    Frequency Generation Without An Oscillator Ckt:multisim Simulation

    Or find out how transistors are biased so that they pass sufficient current to do the job but not enough to damage them.
  15. duke37

    Frequency Generation Without An Oscillator Ckt:multisim Simulation

    To get a tuned oscillator you will need a tank circuit consisting of an inductor and capacitor. Various methods are used to tap into this circuit to provide power from the transistor and another tap is used to drive the transistor. If the circuit shows an oscillation, it will be using the...
  16. duke37

    Is this transformer question correct?

    I wish people would not use the term windings for turns. The transformer has a turns ratio of 4:1 so the voltage will be 4:1 and the current will be 1:4. It all depends on which winding is the primary. It is not specified in the question.
  17. duke37

    Replace Relay with TRIAC?

    I car has an electrial system with large currents and long inductive wires. Any disturbance to the steady state will generate voltages in all sorts of places. This is colloquialy called trash. A MOSFET is very sensitive to voltages at the gate so funny things can happen unless this trash is kept...
  18. duke37

    Partialy Discharging Capacitor

    I thought that the output of flashes for cameras were controlled by altering the length of the flash rather than the intensity.
  19. duke37

    Wiring a relay for an electromagnetic lock

    If the lock is stuck when it is not powered, then not powering it with a relay will not help. Check that the solenoid does not have some residual voltage across it.
  20. duke37

    DC Voltage conversion for miniature bulbs?

    I would experiment with a boost convertor to change the 3V DC to 6 or 12V.DC. Where does the 3V DC come from? Do you need a thick filament for optical reasons? How critical is the voltage?
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