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  1. BobK

    Resonance

    Oh, I missed that fact that the range of frequences if from .5 to .57 Hz. I guess the power radiated would fall below the legal limits then, so my comment above was wrong :)
  2. BobK

    Help with potentiometer in series with led

    LEDs don't work that way. You cannot dim them by varying the voltage from 0 to their operating voltage. The way to dim LEDs is by PWM or a variable current source. Not to mention that we have no idea of what kind of driver is being employed in your device. Bob
  3. BobK

    Resonance

    In other words, build an illegal transmitter. Bob
  4. BobK

    Emitter Base Breakdown

    Interesting question. I thought exceeding that voltage would damage the transistor. Bob
  5. BobK

    Solar Dragsters project - need advice

    A 4.5V 90ma solar cell should be enough to run a small motor continuously. Here is an example of one that should work. http://www.karlssonrobotics.com/shop/toy-dc-motor-with-leads/?gclid=CKW6tdPN2bUCFQdU4AodgAcAKA Bob
  6. BobK

    reg:ROBOARD 110

    Sure. You build a robot. The robot will have a variety of motors, actuators, servos and sensors, and maybe some flashing lights. You hook these up to the roboard and write a program to make the robot do what you want it to. For more info, please enroll in a 4-year degree program in...
  7. BobK

    wanting a solution to cockpit noise

    If a simple circuit would do the job, the commercial versions would not be $1000. I suspect that you need a DSP and some pretty complex code to do anything good. Bob
  8. BobK

    alternating the three lamps in a signal head

    Look up "traffic light circuit" on google. You will want your electronics to drive solid-state relays to switch the lamps. Bob
  9. BobK

    Interpreting Circuits

    Pretty much all circuits are combintations of more basic circuits connected together. Once you have been doing this for a while, you recognize the basic circuits and their functions. That said, every now and then you will see a, sometimes very clever, circuit that you have no idea what it is...
  10. BobK

    Change current output of PSU

    Not offhand. There are 5A regulators out there though. Not sure they have adjustable current limit, but there is sometimes a circuit in the datasheet to do it externally. Bob
  11. BobK

    Change current output of PSU

    Pretty much everything. You need a larger transformer. Higher current diodes. A larger filter capacitor and a different circuit or a different regulator IC. Perhaps this will help if you want to keep the L200...
  12. BobK

    reg:ROBOARD 110

    From their web site: Bob
  13. BobK

    planar vs finfet transistor

    Removed incorrect response. Bob
  14. BobK

    Secret Box Project

    If you look on ebay for 3-axis accelerometer you find many little modules that say "for Arduino" but there is nothing making it specific to Arduiono. The simple ones just seem to have 5 pins, power, ground, and 3 analog outputs. You could use these on any micro that has at least 3 analog input...
  15. BobK

    Secret Box Project

    Personally I would use a PIC, probably a PIC12F1840, but that is because that is what I am experienced with. I have no experience with accelerometers. Sparkfun sells several of them either as chips or modules. Bob
  16. BobK

    Secret Box Project

    It looks to me like there are 4 contacts (brass bars) arranged such that a unique set of 2 of them are connected for each orientation of the cube. A more modern way would be to use a 3-axis accelerometer, like phones and tablets use. Bob
  17. BobK

    What value of capacitor to drop the ripple %

    The ripple voltage is a percentage of output voltage. 3% of 10V would be 0.3V. dt is delta time. The time for one cycle. Assuming 50Hz this is 1/100th of a second, assuming full wave rectification. BTW: 10F is a HUGE capacitance, in the range of supercapacitors. It might be very...
  18. BobK

    Secret Box Project

    If you watched the whole video you would know. If you are still puzzled, what do you think is the function of the brass ball in the cage? Bob
  19. BobK

    What value of capacitor to drop the ripple %

    So the OP has 10V 500A which is a load resistance of 0.02R and wants 5% ripple which is 0.5V. So we have: Vr = Vp / (Rl * C) * dt or C = Vp / (Rl * Vr) * dt or C = 10 / (0.02 * 0.5) * 0.01 = 10F I knew it would be big, but that is enormous! Bob
  20. BobK

    Mini-Amplifier

    Here is a chip that does the entire reverb function. Reverb Chip Not an easy build for a beginner though, 28-pin SOIC. Bob
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