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  1. duke37

    Motor not turning on but drawing excessive current.

    If the motor started up without assistance, then it is likely that it is an intermittent switch which is causing the trouble. Capacitors or motor windings are not going to repair themselves. The size of capacitor is determined by the motor manufacturer, there will be many parameters which will...
  2. duke37

    LED driver transistor kind of noisy

    The two diagrams you give are not connected so it is difficult to see what is happening. You say that there is a pulse output, pulses have high frequency components and this could be the source of the noise.
  3. duke37

    Motor not turning on but drawing excessive current.

    If the capacitor is start/run the capacitor will be permanently wired in series with one winding. If it is start only it will be in series with the switch which will be at the end of the motor. Larger single phase motors can have the capacitor remote from the motor and connected by a timed relay...
  4. duke37

    Making a Transformer

    500k is an unbelievable transformer impedance especially on a home wound transformer. Is this the impedance of the measuring instrument? Show a drawing of your circuit and specify the voltage and frequency of the primar supply
  5. duke37

    Motor not turning on but drawing excessive current.

    The hump is a capacitor which may be start or start/run. If the cap is for start only there will be a centrifugal switch to disconnect it when up to speed. These switches often cause trouble.
  6. duke37

    LED driver transistor kind of noisy

    The BC547C can manage 45V so there is plenty of room here. When I suggested slowing down the switching, it may be that the clicks have a much higher frequency component than the basic circuit is operating at. A 100nF capacitor from Q5 base to ground would not affect the basic signal (100Hz) a...
  7. duke37

    LED driver transistor kind of noisy

    If placing a capacitor across the transistor makes no difference I would suspect that the interference comes from an earlier stage. Try disconncting R58 and see if the problem is still there. Try better bypassing of the power supply. Try slowing down the switching device which controls the...
  8. duke37

    laser alarm problem

    That is an excellent drawing, I wish I could do as well. I have not studied the circuit around the Johnson counter but the 741 has the + input connected to ground with R1 just wasting power. This cannot be right. What does R6 do?
  9. duke37

    aerial tv signal ampliication?

    A reasonably modern TV will have a good input circuit, probably as good as a booster amplifier. Thus putting a booster amplifier in front of the set will help very little if at all. A booster amplifier at the aerial however is beneficial. The signal is attenuated in the down cable and boosting...
  10. duke37

    laser alarm problem

    I could not make out much from the video, it would be better to sketch out the circuit and scan it and post it. The circuit you show does not have a reset. This circuit can be made to latch by feeding some positive feedback from p2 to p6 (try 100k). Look up Schmitt trigger. The problem here...
  11. duke37

    Variable resistor pinouts

    This is a variable resistor going from about zero to about 100k. Resistors can be connected either way round so you could interchange p1 and p2/p3 without problems. There may well be an optimum way of connection in that the control would work the oposite way wih the connections the other way...
  12. duke37

    3. way Light help

    You seem to know how two way switches work. There is a loop going from the line to neutral with the switches and lamp in that loop. The lamp can come first or the switches, if the switch is off, anywhere in that loop, the light will not work. However, you should think about safety. The switches...
  13. duke37

    Remote Controlled Light Fixture

    Parabolic reflector A parabolic reflector works like a lens. It is intended to focus light from one point to another. It is likely that you want to illuminate all your plant and not just one leaf, thus a parabolic focussed reflector is not needed. Some aluminium cooking foil stuck to a curved...
  14. duke37

    relay needed... help

    I attach a diagram of two 2 pole changeover relays with a switch for each direction. If you are using semiconductor switches, do not forget a flywheel diode across each relay coil.
  15. duke37

    relay needed... help

    In order to change the motor direction you need a two pole change over relay. Connect the power to the common contacts and the motor to the unenergised contacts and also swopped over to the energised contacts. This ensures that the motor cannot be connected both ways at once. If it were, it...
  16. duke37

    Comparator issues:newbie

    The 741 cannot pull its output all the way down to the negative supply (here the ground). You can get op-amps with fet output which can do this or you can provide a negative supply. You may get a low enough output voltage by putting a resistor to ground.
  17. duke37

    Comparator issues:newbie

    What power supplies have you got? Is there a negative supply? Give a rough sketch of your circuit.
  18. duke37

    How to Identify Between which is IR sensor and which is reciver.....

    Could you use a TV zapper to check which one is the receiver?
  19. duke37

    12V timer

    In simple relaxation oscillators, a capacitor is charged and discharged. When longer times are required, the capacitor leakage can become significant and, in the extreem, the charge current will be less than the natural discharge current and the oscillator will not work. The leakage current...
  20. duke37

    12V timer

    The 555 would certainly do the job. For simple oscillators I tend to use a 4093 Schmitt trigger nand. This needs a timing capacitor and a feedback resistor, in your case, two resistors could be used in series with diodes so one resistor is used for on and one for off. The time is a bit long for...
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