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  1. duke37

    Resistor??

    I have not learned to count, I think it is 100000pf or 100n or 0.1uF. Please check.
  2. duke37

    Resistor??

    This is a capacitor not a resistor. Why do you need to change it? Mullard made these, I have lost my data book. brown 1 black 0 yellow 4 black 0 red 2 yellow 4 So 10000pF = 10nF then black 20% tolerance, red 250V ?
  3. duke37

    help with oscillator driving comparator

    The oscillator will be somewhat sensitive to load and the comparator load will change through the cycle. You could add a voltage follower as a buffer between the oscillator and the comparator.
  4. duke37

    PC power supply Output 24VDC

    Why not put a meter between the -12V pin and +12V pin and see what you get?
  5. duke37

    help for led series circuit

    Three leds in series will need about 8.55V , there will be 1.25V across the LM317 resistor, leaving 2.4V across the 317 from a 12.2V supply. This may not be enough, look up the details of the 317, the technical term is dropout voltage. If you have a 12.2v stabilised supply, then a simple...
  6. duke37

    Im in need of a motor

    The motor controller should drive the motor you show and should do a much bigger motor. You will need a power supply to provide an input. The motor is very diddy and may only be able to drive very small equipment. The aerodynamic drag will be significant at high speeds but I do not know how...
  7. duke37

    help for led series circuit

    The 2.2 ohm resistor implies that you are using the LM317 as a current regulator so you are not suplying 12.2V but 570mA, or trying to. What is the voltage required by the LEDs? What is the input voltage when running under load? What is the power dissipation in the LM317 and is there...
  8. duke37

    Im in need of a motor

    You said the motor would be turning at 3500 rpm. 3500 * 1.75 = 6125. Use ball bearings, small ones can run at 100,000 rpm The shafts must be dynamically balanced for safety.
  9. duke37

    Im in need of a motor

    If the motor is running at 3500 rpm then the two driven shafts will be running at 6125 rpm. Plain bearings can manage this speed but need to be made very accurately. Ball bearings would be good if there is no significant side load. If you are spinning metal poles at such speeds, I suggest...
  10. duke37

    Power inverter output too high

    A 230V AC supply will have a peak voltage of 325V. It depends on the shape of the waveform as to what is measured. Most meters measure the mean voltage and then bodge the result to match the RMS value assuming a sine wave. The twiddle pot may be to adjust the frequency rather than the...
  11. duke37

    Simple Variable DC Power Supply

    You shoud have an electrolytic capacitor across the input and another across the output to ensure stability.
  12. duke37

    Simple Variable DC Power Supply

    The circuit you show will not work ! The LM317 will only work with direct current input. So, Rectify the input AC Smooth the DC Pass through the LM317 Make a DC to AC converter (audio amplifier?) What are you trying to do? Heat sinks are often connected to one of the chips terminals...
  13. duke37

    3ph motor running on square wave?

    I see no way out of this other than to try it. The square wave has a large amount of harmonics which will produce currents and power loss. The power supply may not like the load either, it will be far from resistive.
  14. duke37

    Woo-Woo Protecting one dc circuit from the other

    My runner beans are growing well, all due to RADIANT energy.
  15. duke37

    Woo-Woo IGBT Isolation and DC to DC converters

    You will not run far in a vacuum. Post a diagram of the circuit that you have, describing what it should do and what it actually does.
  16. duke37

    Homemade Shunt Resistor.

    Doing it your way puts the meter at risk. A better way would be to measure the voltage across the shunt. Four point connection can be used, the current is put through the entire shunt and the voltage is measured inside the end connections. This would give a better measurement but you should...
  17. duke37

    Need guidance; newbie project - LED controllable steps

    I do not understand quite what you wish to do. If you have a signal at each 'step' and just need to light a led, then all you need is a led driver which would probably be a transisor. To half light an adjacent led, then another driver with a larger series resistance will do it. The drivers...
  18. duke37

    Fence Charger Problem

    The red thing may be a voltage dependent resistor intended to limit voltage transients on the input. If so , it is not essential for the fencer to work. 1. Does the fencer work on battery or mains? 2. Is there a printed circuit board? 3. Is there power getting to the board? 4. Is the big...
  19. duke37

    How can i increase the wireless range of this device?!!!

    A Yagi will increase the distance that a signal can be received. This is achieved at the expense of a restricted field of view. A Yagi is optimised for one frequency but your frequency range is very wide. If you know the transmitted power and frequency and transmitter antenna gain, then...
  20. duke37

    Requires 70 Volts AC

    If you cannot find a 70V transformer, you could perhaps find two 36V (18-0-18)transformers which could be connected in series. Or three 24V (12-0-12) in series.
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