Search results

Search Forums New Posts
  1. L

    Person needed to build a chess computer using our chess software

    Xboard is open source software which acts as a front end for a chess engine to interface a computer display. The Novag Citrine is an electronic chessboard with physical chess pieces. In your design concept, what part is physical and what part is displayed on a screen? Is there a chess engine...
  2. L

    DC generator problem...HELP!

    Since this is a brushless motor the first question would be whether the commutation controller is internal or external. If internal then it can't be used as a generator, and trying to do so may result in the back EMF frying the internal controller. If the controller is external, then you...
  3. L

    Use Electromagnetic energy to crush a aluminium can?

    The 240 VAC is given as an RMS value. The peak voltage of an AC RMS value is 1.414 times the RMS. The capacitors will charge to the peak value of 340 volts DC. So make sure the capacitors are rated for at least 400 volts, possibly much more unless you add some quenching circuit to the coil.
  4. L

    Help in a passive low pass filter

    In order to solve this problem you need to use phasor algebra. Phasor algebra has the advantage that it reduces steady-state sinusoidal circuits to the form of pure resistance circuits. Once the problem has been converted to the frequency domain it is essentially a resistive problem. The only...
  5. L

    Simple LED help please

    Since these are blinking LED's one concern would be whether the voltage across the LED would exceed the rated value during the OFF period when the current is low and very little voltage is dropped across the resistor. How might that affect the LED? I think I would try a 4.7v Zener diode across...
  6. L

    Lighting system for Didgeridoo

    There are two approaches for implementing your idea: analog & digital. The analog route would utilize an array of bandpass filters at different center frequencies with the outputs rectified to provide an indication of the amplitude of each frequency component. Then you figure out an LED...
  7. L

    How to make an electronic spark with low voltage?

    Check out this item: "302301 - Model Rocket Igniters" http://www.estesrockets.com/review/product/list/id/142/ You can make your own. Use #30 AWG Nichrome wire, wrap the center of a 4 cm piece around a 1/32" mandrel once or twice, dip the coil into a paste of gunpowder, aluminum powder and gum...
  8. L

    Plasma Torch Height controller (not so simple voltage divider)

    I would use something like the attached circuit to present the -300 Volt signal to the Arduino ADC input. Note that there will be a small positive offset that you can subtract out following the conversion. The RC filtering is based on a guess about the characteristics of the plasma signal.
  9. L

    Plasma Torch Height controller (not so simple voltage divider)

    Indeed, there are many books written on modern control systems theory; however, they do require that you write the differential equations which govern the motion of your physical system prior to designing the feedback electronics for controlling that system. Otherwise you can start with a...
  10. L

    Can capacitors collect ambient energy?

    The technical term for this effect is capacitor soakage or dielectric absorption.
  11. L

    Need help asap 50 doller reward....

    I have included an example of how to integrate an exponential function. If you do not have a table of integrals for standard forms, one can be found at http://integral-table.com/integral-table.pdf
  12. L

    Pressure Sensor Rate of Change Limit

    There are some interesting ways to use discrete logic for checking the pressure change hourly for five hours; however, it starts with a Sample & Hold circuit. With the parts you have available, can you build a S&H module that can read the sensor voltage and then hold that value with only a few...
  13. L

    Summing difference amp outputs

    I would ask whether these 'kit' circuits have a substantial voltage difference between the virtual ground and physical ground like your circuit does. If there is normally no voltage drop across the Zener diode, then no problem. Otherwise there will be some leakage current which is multiplied...
  14. L

    Pressure Sensor Rate of Change Limit

    With a microcontroller you do not need any external logic like that. It is all done in code. Now I should warn you that the last time I worked with microcontrollers, it was using the CDP1802; however, I would expect they have gotten more sophisticated and easier to work with since then...
  15. L

    Pressure Sensor Rate of Change Limit

    Do you need to check every hour or just once at the five hour mark? If it is every hour, then I would recommend using a 10-bit (or greater) analog-to-digital converter with a micro-controller and opto-isolators for driving power relay switches. You will also need to condition the sensor output...
  16. L

    Evolution of Electronics

    Edison was trying to understand the observed phenomenon of vapor deposition but discovered thermionic emission. http://www.ieeeghn.org/wiki/index.php/Edison_Effect The name Edison Effect was given to a phenomenon Edison observed in 1875, although it'd been reported two years earlier in...
  17. L

    Voltage comparator debouncing

    Circuit operation here is tied directly to the nature of the probe contact bounce. Not sure whether the probe signal will be as clean as depicted in your diagram. If you will get a contact bounce more often than 23 ms when moving the probe, then you have succeeded in suppressing any output...
  18. L

    why charge pumps?

    The virtues of charge pumps are simplicity and efficiency. However, inductorless DC-DC power conversion is generally reserved for low-power applications where the voltage change from source to load is limited. Higher currents and greater voltage change generally requires use of inductors or...
  19. L

    nodal analysis?

    This is a particularly easy example. There is only one node whose voltage is determined by the circuit and the applied voltage sources, so only one node equation is necessary. The sum of all currents entering and leaving node V1 must equal zero. Any particular current either entering or...
  20. L

    differential transistor pair

    I don't understand why you would divide the differential voltage in half. The situation as described seems to be one in which there is no common mode voltage input. Perhaps the following article on measuring CMRR will suggest a way to clarify the problem...
Top