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  1. duke37

    Need help with this voltage regulator circuit simulation

    Harald, I looked at the diagram in TL431TI.asy and the first part of the circuit was there which I understood was the trouble. There was a regulator and then a blank area which pesumably originally had a chip of some sort. Some time ago I tried to simulate a circuit with analog and digital...
  2. duke37

    Universal motor bi-direction speed control

    Some drills use a simple triac control with the speed varied with a potentiometer.. A lamp dimmer is a similar circuit and can be used with a universal motor. The dimmer is not complicated, just a potentiometer, capacitor, diac and triac. If running off the mains, you will need to make...
  3. duke37

    Driving opamp output to near ground?

    To get the output closer to ground, you will need to lower the resistance to ground, not increase it. I could not find 2.5M resistance on the output of the op-amps in your circuit. U17 has the two inputs connected with a 1k resistance, how is this supposed to work?
  4. duke37

    Constant Battery charger

    To get a free energy device, you have to produce more energy that you provide. Do some sums on the energy dissipated as heat by each component and tell us the source of more energy than this. It's entropy man !
  5. duke37

    Need help with this voltage regulator circuit simulation

    There is an IC missing in your diagram - LTspice does this. 13V as the input to what? The regulator should stop high voltages comming through from the rectifier. I assume that that the FET gate is not dropped low enough to turn it fully off. Why do you need all this protection? What does...
  6. duke37

    Help please (building a tracker mount for photographing the stars))

    I have never done this, others on this forum have, but here are some comments. To drop the speed of a 12400 rpm motor to 1 rpm will not work. It will either stop or go too fast. You will need a gearbox to get the motor speed up to a reasonable value. Aim for about 1000 to 5000 rpm. It...
  7. duke37

    Need help with this voltage regulator circuit simulation

    Did you get the simulation to work using my parameters?
  8. duke37

    heating alternatives

    Or quarter the power.
  9. duke37

    Need help with this voltage regulator circuit simulation

    Divide and rule. I managed to simulate the rectifier. It will take some time to do 5 sec. Add the next part of the circuit, that will slow it down.
  10. duke37

    Hot Wire Cutter Power Supply

    You should connect the capacitor across the input of the PWM module, it can be connected with the wires from the battery charger. It would be good to insulate as much bare wire as possible. Make a little plywood box to enclose the module and fix the module and capacitor to the box with hot...
  11. duke37

    Hot Wire Cutter Power Supply

    The idea of using a battery charger is a good one, it gives a lower voltage, measures current and is isolated from the mains. In other words, it is reasonably safe to handle. So why did you muck about with it? If you do manage to get it working again, will it be safe?
  12. duke37

    SMPS components temperature?

    A thermocouple measures the temperature difference of the hot and cold junctions. Normally the hot junction is the one you are interested in. The junction will be heated by the component it is glued to and cooled by conduction along the wires. To get an accurate reading you should embed the...
  13. duke37

    SMPS components temperature?

    Gluing thermocouples to the components will give the wrong answer due to heat being conducted into the thermocouple. This can be reduced if the thermocouple is glued for say 10mm flat on the component. There are ways of measuring emissivity but it is complcated. The best way of getting the...
  14. duke37

    Car Parking Sensors Help Needed

    Audacity can measure frequency. "The Enhanced Autocorrelation function is very good at identifying the pitch of a note." Edit I have tried to get information from Toyota they have a factory nearby) without success. To give an amswer they want country, model and chassis number.
  15. duke37

    Car Parking Sensors Help Needed

    Kris has beaten me to it, they get up early in NZ. There are programs, perhaps even Audacity, which will do a Fourier analysis to see the frequency constituents of a waveform. I suggested getting a tame guitar player to estimate the note. There are also guitar tuners which can measure the...
  16. duke37

    Fan Starting Problem

    The lubricant may have gone gloopy and will be less viscous when warm.
  17. duke37

    Help with a battery powered tube preamp

    The circuit refered to does not specify B+ voltage. The tube (USA) needs 12V on the heater, some will run on a B+ as low as 12V. 1M resistor with 100V across it will pass 0.1mA. This is the maximum that could be passed. If the B+ is lower and there is voltage across the tube, then the...
  18. duke37

    Will this circuit work for a 3A load?

    I will try to post for the third time, I hope they all do not show. The circuit will work but not for long, the 1N4007 is a 1A diode. The IRFZ44 55V 49A 17.5mohm FET and will be adequate. I would fit a fuse to protect against long term high voltage.
  19. duke37

    Car Parking Sensors Help Needed

    The closer the microphone is to the sound, the better but there is sound in the cabin to be heard and it can be sensed and amplified. If the sound level is low, it may be necessary to filter the signal to eliminate extraneous sound. If a filter is used, then it will need to be tuned to the...
  20. duke37

    Fan Starting Problem

    Seems like sticky bearings to me. Does the fan spin easily? Dismantle, clean bearings, assemble and you will have the wind. Fans need very little torque to start so the motors are not designed to have a high starting torque.
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