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  1. duke37

    Adjustable speed motor

    There are many motor types which can be varied in speed, they go from cassette recorders to locomotives. You need to specify power, speed, speed regulation, torque, voltage supply etc. Building a motor would be very difficult.
  2. duke37

    BMW D12 Marine Diesel rectifier/regulator project

    Consider using a programmable zener for D3 (e.g. AS431) so that it can be trimmed to the correct voltage.
  3. duke37

    water level high point, 12V relay kick on help

    Why are you worried about price if you are dealing with heavy water? Washing machines use a pressure switch to control the fill. One of these could be used. A normal ball valve lever with a magnet actuating a reed relay would be my preferred solution.
  4. duke37

    BMW D12 Marine Diesel rectifier/regulator project

    You can test each half of the circuit without digging out the epoxy. If you find the faulty half, that is the only piece that you will have to make but you will need to keep the original box also.
  5. duke37

    BMW D12 Marine Diesel rectifier/regulator project

    The Schottky rectifiers will have a lower voltage drop than standard diodes so will generate less heat, a good thing. The SCR is a bit over the top, a smaller one may be more sensitive. The Zener has a tolerance of 5% so you may have to trim the voltage in some way. As I said...
  6. duke37

    BMW D12 Marine Diesel rectifier/regulator project

    The circuit can be split into two parts. 1. The high current rectifier D1 and D2. You will need rectifiers of 100V and 25A 2. The control circuit. It is not easy to give component details, The Zener will need to be about 12V. The output will be the zener voltage plus the drop across the...
  7. duke37

    How to verify my ac-dc adapter is ok?

    You have tested the transformer and found two faults. There should be no connection betweent the primary and the core. There should be no connection between the secondary and the core. If the voltage has been high enough to break down the spool insulation, the windings are probably damaged...
  8. duke37

    Gear help

    You have not said what you want the speed for. I would think that gears are a bad idea. How do you lubricate them? To spin something very fast, you need very special bearings, magnetic or air and a very strong structure that will not explode under the forces. The turning force can be...
  9. duke37

    Gear help

    The belt will step up 3 times. The gear will step up 6 times. That is 18 times. 12,000 times 18 = 216,000 You will need a high powered motor to supply the energy lost in windage and bearings. You will also need earplugs.
  10. duke37

    Generators Work...

    You make life difficult by not using SI units. A radian is a measure of angle. There are 2*pi radians in a circle. To go from RPM to radians/sec, multiply RPM by 2pi and divide by 60. Torque is a measure of tangential force times distance from the rotary axis. I do not see how you find...
  11. duke37

    Generators Work...

    That seems about the right principle, however the equation is:- Power (W) = Torque (N.m) * Speed (radians/sec) This is the power going into the machine, you will get less out.
  12. duke37

    help with delay circuit

    If there is an oscillation, there is feedback somewhere. Make sure that all the grounds are connected to a common rail and that the power supply is bypassed properly. You do not say if you are using the delay or echo circuit. Start with the delay circuit as this is simpler and does not have...
  13. duke37

    design and impliment class c radio frequency power amplifier

    In your other post, you said you wanted a 100mhz amplifier, I presume that you need an amplifier running at 10^9 faster than this, i.e. 100MHz. What power do you want? Valves would be easier to use than transistors but are lethal. In the US, the ARRL publish a handbook which gives...
  14. duke37

    Rectifier Problem, Analog to Digital Converter Please Help! Kind of Urgent.

    The rectifier is an inverting circuit. With two equal resistors, it will output the same as the input voltage but with the polarity inverted. When the amp is supplied with 3.3V, it can manage an output of 3.3 - 0.6 = 2.7V so the measuring input range is 0V to -2.7V. 1N4004 diodes are a bit...
  15. duke37

    irregular tigger pulse why?

    Is the digital scope fast enough to resolve the time accurately? Try an analogue scope.
  16. duke37

    oscillator specifications needed

    I am surprised that a 555 cannot manage 1MHz. What sort of frequency accuracy do you want? For a very simple oscillator, you can use a gate in a 4093, put a resistor from output to input and a capacitor from input to ground. The frequency will be apoximately 2.7/(R*C). The spare gates...
  17. duke37

    blowing up capacitors

    Prynhawn da 9 times 5 = 45, well above the capacitor rating. Elecrotolytic capacitors should never be connected with reverse polarity.
  18. duke37

    modified sinewave ups

    Bob, That simplifies things, it may be possible to use two push-pull inverters, one for the positive half of the waveform and one for the negative. A switch would be needed to change from one to the other. Boost converters using one switching device are beyond my ability to design but...
  19. duke37

    modified sinewave ups

    This looks to be a complicated project. Take 12V DC, convert to +/-330V DC with push-pull invertor. Generate a sine wave at 50 Hz. Use two buck convertors to reduce the 330V to match the sine wave, one for the positive part of the sine wave and one for the negative. This can be done with...
  20. duke37

    Motor Unit operation

    I do not know the standard which you have but assume that if the motor runs at 3600 RPM that you are in Japan or America and have a 60 Hz supply. Shaded pole motor which are very inefficient and often used to drive fans (where the torque drops when speed drops) can be controlled with a simple...
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